Cressi Archimede II User Manual

Manuale d’istruzioni
Manuel d’instructions
Gebrauchsanweisung
Manual de instrucciones
User’s Manual

User’s Manual

User’s Manual

ENGLISH

TABLE OF CONTENTS

1. - INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 161

1.1. - Main specifications . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 161

1.2. - Safety measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 161

1.2.1. - Definitions of danger, warning and note. . . . . . . . pag. 161

1.2.2. - General recommendations and safety measures. pag.162

1.3. - Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.163

2. - BEFORE DIVING . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.165

2.1. - UFDS display and controls. . . . . . . . . . . . . . . . . . . . pag.166

2.2. - On surface, before diving . . . . . . . . . . . . . . . . . . . . pag.166

2.3. - Parameters setting . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 167

2.3.1. - Dive program parameters setting ( ). . . . . . . . . p a g . 167

2.3.2.- Dive planning ( ). . . . . . . . . . . . . . . . . . . . . . . . pag.169

2.3.3. - Rapid visualisation of set data ( ) . . . . . . . . . . pag.169

2.4. - program parameters setting

(depthometer/timer). . . . . . . . . . . . . . . . . . . . . . . . . pag.169

2.5. - Instrument general setting . . . . . . . . . . . . . . . . . . . pag. 170

2.5.1. - Maximum depth alarm. . . . . . . . . . . . . . . . . . . . . . . pag. 170

2.5.2.- Date and time adjustment ( ) . . . . . . . . . . . . . pag. 171

2.5.3.- Units of measure setting . . . . . . . . . . . . . . . . . . . . . pag. 171

3. - WHILE DIVING: PROGRAM DIVE . . . . . . . . . . . pag.173

3.1. - Air dive ( ) . . . . . . . . . . . . . . . . . . . . . . . . . pag.173

3.2. - Nitrox mixtures dive ( ). . . . . . . . . . . . . . . . pag.174

3.2.1. - Before a Nitrox dive . . . . . . . . . . . . . . . . . . . . . . . . pag. 174

3.3. - Nitrox parameters setting . . . . . . . . . . . . . . . . . . . . pag.174

3.3.1. - PO2 partial pressure setting . . . . . . . . . . . . . . . . . . pag.174

3.3.2.- Nitrox mixture/s oxygen fraction F02 setting . . . pag.175

3.3.3.- Mixture changing while diving . . . . . . . . . . . . . . . . pag. 176

3.3.4 - CNS toxicity display ( ) . . . . . . . . . . . . . . . . . . . . pag. 177

3.3.5.- PO2 alarm ( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 178

3.4. - Curve dive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 178

3.4.1. - Ascent rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag. 178

3.4.2.- Safety Stop ( ) . . . . . . . . . . . . . . . . . . . . . . . . . pag. 179

3.4.3.- Decompression forewarning ( ) . . . . . . . . . . . pag.179

3.5. - Decompression dive ( ) . . . . . . . . . . . . . . . . . pag.180

3.5.1 - Omitted decompression stage alarm . . . . . . . . . . pag. 181

3.6. - program (depthometer/timer) . . . . . . . . . . . pag. 181

4. - ON SURFACE AFTER A DIVE . . . . . . . . . . . . . . . pag.183

4.1. - Data processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.184

4.1.1. - Surface interval ( , , ) . . . . . . . . . . . . . . pag. 184

4.1.2. - Logbook ( ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.185

4.1.3. - Dive historic memory ( ) . . . . . . . . . . . . . . . . . . pag.186

4.1.4. - Dive profile ( ) . . . . . . . . . . . . . . . . . . . . . . . . . . pag.187

4.1.5. - Data PC transfer: compatible PC interface ( ) pag. 187

4.1.6. - Instrument reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.188

4.2. - Simulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.188

4.2.1. - Dive simulator ( ). . . . . . . . . . . . . . . . . . . . . . . . pag.188

4.2.2.- Surface interval dive simulator ( ). . . . . . . . . . pag.189

5. - CARE AND MAINTENANCE. . . . . . . . . . . . . . . . . pag.189

5.1. - Battery replacement. . . . . . . . . . . . . . . . . . . . . . . . . pag.190

6. - TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . pag. 191

6.1. - No decompression limits by the first dive

in a series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.192

6.1.1. - Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.192

7. - WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pag.193

1. - INTRODUCTION.

Congratulations on your purchase of the Archimedes II com-
puter. The Archimedes IIis a sophisticated computer offering
numerous performance features which ensures the utmost
in performance, reliability and safety.

1.1. - Main specifications.

• Algorithm. The Bühlmann ZH-L8 algorithm has been refi­ned by Randy Bohrer in order to make available a more
complicated RGBM program. The result is an algorithm
very similar to ZH-L16 which is less penalizing related to
water temperature and exceeding ascent rates.

• Tissues: 12 Tissues with saturation hemi-phases between
5 and 640 minutes;

• PROGRAM
Dive data full processing. During air or Nitrox dives (including
decompression dives) two different nitrox mixtures may be
utilized.

• Setting of mixtures. P02 can be set between 1.0 bar to 1.6
bar. FO2 settings between 21% to 50% and 21% to 99%.

• The Archimedes II will allow for a nitrox dive subsequent to
an air dive even during de-saturation.

• Possibility of PROGRAM setting (depthometer/timer)

• Large UFDS display system allows for ease in reading and
understanding of values.

• Replaceable display protecting screen

• Battery replacement by user

• Manual dive planning (Scrolling)

• Unit of measure changing from metric to feet and °C to °F.

• Sound and visual warning systems

• Nitrogen saturation graphic indicator

• CNS oxygen toxicity graphic indicator

• Back-luminescent display

• Dive simulator (surface interval setting for a subsequent dive)

• Calendar and clock

• Logbook (30 h or 60 dives) including dive profile

• Dive historical memory

• Reset button allows for multi diver activity.

• PC interface (optional)

1.2. - SAFETY MEASURES.

1.2.1. - Definition of danger, warning and note.

Please read the user guide thoroughly prior to using the
Archimedes II.
Prior to reading the operational directions, please understand
the following definitions:

 DANGER: indicates a situation (or procedure) that

may be dangerous to the diver’s health and safety.
WARNING: indicates a situation (or procedure) that may

be dangerous to the diver or damage the instrument
NOTE: stresses important information.

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ENGLISH

1.2.2. - General recommendations and safety

measures.

WARNING: Read the directions! Please read users’

guide carefully, including the safety measures section.
Have a thorough understanding of the instrument’s use,
functions and limitations before using it! DO NOT use the
instrument without having read each chapter of the users’
guide!

 DANGER: A underwater diving computer can never

completely eliminate the risk of decompression sickness.
The computer does not take into any account a diver’s
physical conditions which may vary daily. It is recommen­ded that a medical examination is completed prior to com­mencing any underwater diving activities, and to assess
one’s own physical condition before each dive.
Circumstances such as cold water temperature (less than
10°C – 50F), poor physical condition, multiple dives made
on subsequent days, weariness, use of alcohol, drugs, or
medication and dehydration my increase the risk of
decompression sickness.. It is recommended to avoid all
such situations that may increase the likelihood of decom­pression sickness.

WARNING: The Archimedes II should be used only by
properly trained and certified divers. No computer will
replace proper underwater training.

WARNING: The Cressi-sub Archimedes II computer is
designed for recreational sport diving only. It is not desi­gned for commercial use requiring increased diving activity.

WARNING: Before using the computer, please check the
battery life status and the visibility of the LCD display. DO

NOT dive if the instruments’ indications are not clear and if
the battery is low.

WARNING: While diving, be equipped with a depth
gauge, diving watch and dive tables. Additionally, check
the air capacity in your diving cylinders.

 DANGER: Do not dive at high altitudes before the

instrument has automatically switched on the program
corresponding to the altitude at which you are. Please
check the altitude level on the display. Please be advised
that diving at higher altitudes than 9,842 ft. above sea level
involves an increase risk of decompression sickness.

 DANGER: Before flying, wait until the icon "No Fly

Time" on the computer display has disappeared.
WARNING: The information offered on the computer is

strictly personal for the individual who used the instru­ment during a dive or a series of dives.

 DANGER: Cressi-sub discourages the use of this

instrument in decompression dives. In the event that no­decompression has been exceeded, the Archimedes II
Cressi-sub computer will display information related to
decompression, surfacing and surface interval times.

WARNING: Do not dive using Nitrox mixtures without
checking the contents and correct O2 percentage (FO2).
After doing so, set your computer with the mixture(s)’
value so that it may process the decompression compu­tations. Please be advised that the computer only accepts
FO2 values to the nearest whole number. (i.e. 36% not

35.8% )

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 DANGER: The use of nitrox should not be undertaken

without proper training. Nitrox dives will expose the diver
to different risks than those of air dives, including serious
physical damage and, in extreme cases, even death.

 DANGER: As a safety measure the Archimedes II

computer utilizes a PO2 limit set at 1.4 bar even for air
dives. Should you require an additional safely margin, it is
possible to set PO2 at lower values, down to 1.0 bar, by
decrements of 0.1 bar.

WARNING: After a dive with the Archimedes II set in Gage
mode (depth meter-timer). The instrument will not make
saturation and de-saturation computations during the
remaining 48 hours elapsing from the depth meter’s use.

WARNING: Avoid diving activities that result in unsafe
profiles such as "yo-yo" dives, dives with reversed profiles
or several subsequent dives during subsequent days.
Diving activities such as these are potentially dangerous
and present a higher risk of decompression sickness.

WARNING: Please utilize the most conservative safety
factor at all times. By doing so, you will dive more conser­vatively, which will minimize the likelihood of decompres­sion sickness.

NOTE: While flying, the Archimedes II must be stored in
the pressurized cabin.

NOTE: Cressi-sub strongly recommends that all sport
diving activities be conducted within the guidelines of no­decompression diving and at a maximum depth of 132 ft.
Exceeding these perimeters dramatically increases the
likelihood of decompression sickness

As a result of technological advancements/changes, Cressi­sub reserves the right to modify the Archimedes II computer
without notification.

1.3. – Introduction.

The Archimedes II computer is a multifunctional instrument
for sport diving. It will supply information on depth, dive times,
decompression status, ascent rate, and surfaces interval
time between dives. Nitrogen absorption and release is con­tinuously processed by it’s sophisticated software.

Information is displayed in large characters on the
Archimedes II’s
system allows for easy and direct dialogue between the diver
and the computer, ensuring a clear understanding of all the
data needed at any given time.

Additionally, the computer is equipped with a watch and
calendar, a multifunctional dive memory (logbook), and a dive
simulator.

The Archimedes II’s mathematical model can make satura­tion and de-saturation computations of dives carried out with
air, and with up to two different nitrox mixtures. These may be
selected during the dive itself. Nitrox mixture(s) dives may be
set from the maximum PO2 value between 1.0 and 1.6 bar to
oxygen percentage (FOG): the primary (MIXI) between 21% ­50% for O2, the second (MIX2) between 21%-99%.

Additionally, the computer may be set by the user for either
metric (m -°C) or feet (ft. -°F).

Archimedes II Cressi-sub underwater computer may be
connected to a compatible PC, by means of a Cressi-sub

163

User Friendly Display System

(UFD). This

ENGLISH

interface (accessory) and its related software Cressi PC
Logbook (accessory).

Please note that it is very important to read and understand the
users guide and the operation of the Archimedes II. Serious
damages or death can result if theses guidelines are not clearly
understood.

Archimedes II Cressi-sub computer’s watch and calendar
function (see picture 1) are always on, and the related battery
consumption is unnoticeable.

Operational functions are easily visible either by depressing but­tons B (Mode), A or C, or when the contacts get wet during a
diving activity (the dive program turns on at a depth greater than
5 ft. and are illustrated by the figures shown on its large display.

In order to understand all the computer’s functions and their
meaning, the guide is divided into five main chapters, dealing
with every possible situation:

• 1 - Introduction and safety measures

• 2 - Before diving

• 3 - While diving

• 4 - On surface after diving

• 5 - Care and maintenance

The Archimedes II is designed to be easily understood and
operated. It displays only the data needed during specific
situations.

164

Foto Ghisotti

2) Before diving

2) Before diving

ENGLISH

2.1. - UFDS display and controls.

A

B

C

Archimedes II’s different programs are visible by repeatedly
depressing button B (Mode). This is the key to operating the
system. They are clearly indicated by the alpha-numeric
UFDS display. Some programs have sub-menus, which are
switched on by depressing buttons A and C. This will allow as
well as change the setting on the surface. Depressing button
C ( ) engages the display back-illumination.

2.2. - On surface, before diving.

As previously noted, the Archimedes II is always on. When
diving at altitude, it is important to check that the appropriate
altitude adjustments have occurred. This function is carried
out automatically, updating every 10 minutes. Altitude adjust­ment values will be displayed as follows:

no icon ( )- from 0 – 2.625 ft. (picture 1)

- from 2.625 – 5.250 ft. (picture 1-a)

- from 5.250 – 7.874 ft.

- from 7.874 – 19.685 ft.

- more than 19,685 ft. -out of range
Each icon indicates that the computer has automatically
modified its own mathematical model to adjust to proper
altitude.

Archimedes II computer is equipped with a “

Display System

during its operation. Various icons on the display will indicate
the operation that may be carried out at that moment. As an
example, the “light” icon ( ) (at the bottom on the right) indi­cates that by depressing button C the back-illumination will
be engaged. This establishes a direct “dialogue” and a clear
understanding of every function.

” (UFDS) display, which “escorts” the diver

User Friendly

 DANGER: Diving at altitudes greater than 9,842 ft.

above sea level involves an increased risk of decompres­sion sickness.

Diving at higher altitudes than normal may cause alterations
of the nitrogen balance between the human body and the
environment.

166

IIt is recommended that before diving at altitude, wait at least

i

three hours after arriving at your diving destination. This will
allow a partial release of the residual nitrogen from the body.
The atmospheric pressure at higher altitudes is lower than at
sea level. Therefore, the diver has additional nitrogen in his
body than at the lower altitudes. The excess is gradually
released and the balance re-established within a couple of
days. At this point it is important to check:

The low battery indicator. It should not be on or flashing (pic­ture 2 a-b).

The computer display is operating. All liquid crystal segments
should be displaying.

WARNING: Should the display show the symbol of a low
battery (picture 2 a-b), the computer must NOT be used.
Additionally, should it display during a dive, the diver must
immediately surface. A battery replacement is required as
outlined in chapter 5.

2.3. - PARAMETERS SETTING.

In order to set the dive’s parameters, you must depress the
central button B (Mode), and the icon relating to the
you want to use will be shown (picture.3): , for air dives
( ) or Nitrox, mixture(s), or if you want to use
the depth meter /timer program.

NOTE: Archimedes II computer is preset on pro-
gram.

program

2.3.1. - DIVE program parameters setting.

NOTE: Archimedes II computer is preset on pro-

gram.

This is the basic program with which the Archimedes II is set.
It is possible to modify its parameters by repeatedly depres­sing button A ( ), which allows you to select, in the following
order, the dive’s parameters relating to:

PO2 Mix 1 -> FO2 Mix 1 -> PO2 Mix 2 -> FO2 Mix 2

-> Safety Factor -> Max Depth -> OFF/ON -> DIVE

that is:

• PO2 Mix 1 is the partial pressure of the former of the two
Nitrox mixtures, so that Archimedes II can make its decom­pression computations. The diver can set it on values
between 1.0 bar (included) and 1.6 bar (included), by varia­tions of 0.1 bar, obtained at each pressure of button C ( );

NOTE: By varying of max PO2 setting (picture 3), the com­puter also indicates the maximum depth (MAX) that may be
reached with that mixture.

WARNING: Both mixtures’ PO2 factory set on a basic value
(default) of 1.4 bar, both for air dives and for Nitrox mixture
dives. The diver is then following the most conservative
values recommended for sport dives. Different PO2 values
may be set as shown in chapter 3.3. The set value will be
memorized in the computer until the diver chooses another
setting.

167

ENGLISH

• FO2 Mix 1 is the oxygen percentage of the primary Nitrox
mixture (MIX1) set on Archimedes II. The diver may vary it on
values between FO2=Air (21%) – basic setting - and FO2=50
% (included), by variations of 1% O2, obtained at each
depression of button C ( );

WARNING: Archimedes II is factory set with the primary
Nitrox mixture on Air (FO2=21%) and the second additional
mixture on Off (FO2= - -%)

NOTE: During the phase of parameters’ setting, by depres­sing button C ( ), the computer will automatically stop on
standard Nitrox 1 mixture (EAN 32), with an oxygen percen­tage of 32%. By keeping button C ( ) depressed, it will stop
on (Air) setting. This is to allow the FO2 operations setting to
be set quicker. Additionally, it is possible to set other FO2
values for the mixture (in increments of 1%) each time you
depress button C ( ). The constant depressing of button C
will increase the increments rapidly.

NOTE: By varying of the mixture’s oxygen percentage, the
computer indicates the maximum depth (MAX) which may
be reached with that mixture, since it depends on the PO2
value set.

• PO2 Mix 2 is the partial pressure of the latter of the two
Nitrox mixtures (MIX2) that can be set on Archimedes II
computer. It is factory set on the value of PO2=1.4, but it may

be changed by the diver on values between 1.0 bar (included)
and 1.6 bar (included), by increments of 0.1 bar, following
each other at each depression of button C ( );

• FO2 Mix 2 is the oxygen percentage of the second Nitrox
mixture (MIX2) set on Archimedes II computer. It is factory
set on Off (FO2= - -%) and it may be switched on only by the
diver, by depressing button C ( ), on values between FO2=Air
(21%) and FO2=99% (pure oxygen), by variations of 1%, fol­lowing each other at each pressure of button C ( )

• A Safety Factor may be set by the diver at one of three
values (SF0/SF1/SF2). It is factory set at SFO.

WARNING: In order to dive more conservatively, please
change your safety factor any time you feel that you are at
risk of decompression sickness.

• The maximum depth alarm is set on ft. 132 and OFF by the
factory (picture 4 a); it can be switched On and be modified
as well as the depth at which it will start (picture 4b), by
depressing button C ( ).

At the end of the setting, depress button B (Mode) for seve­ral seconds; this will allow you to return to the normal display
(picture 1).

Related topics:

• 2.5.1. - Maximum depth alarm.

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

168

2.3.2 - Dive planning ( ).

i

While on the surface it is possible to go to the Plan function
( ) in order to visualize the remaining time available at dif­ferent depths, without having to make decompression stops
(curve time), only by primary mixture MIX1.
The values are given both for the first of a (possible) series of
dives and during the surface interval between two or more
subsequent dives; in such case, Archimedes II takes into
account the residual nitrogen, therefore reducing the curve
times.
When the computer is set on program, by depressing
button B (Mode) twice, you view to the function ( ), as
shown by the alphanumeric display. The display will show (pic­ture 5, air; picture 5.1., Nitrox) no decompression depths times
between 30 – 157 ft., in depth increments of 10 ft. This is obtai­ned by depressing C ( ), or by manual depth decreases, each
of ft. 10, by depressing button A ( ).

Depress button B (Mode) for several seconds in order to get
back to the normal display (picture 1).

NOTE: PLAN function will be switched off in program
and in this case the computer shows Error.

Related topics:

• 2.3.1. - program parameters setting

• 3.4. - Curve dive

• 4.1.1. - Surface interval.

• 3.5.1. - Omitted decompression stage alarm. (Error)

2.3.3. - Rapid visualisation of set data ( ).

The INFO ( ) icon on Archimedes II Cressi-sub computer

UFDS display allows you to visualize, while on the surface,
every set parameter for your dive in a quick and easy manner
(picture 6), when the computer is set on program.
By depressing button A ( ), the computer will display the set
PO2 and the relating maximum depth MAX (given in m or ft.);
the possible setting of a safety factor (SF0/1/2); the possible
oxygen percentage of the primary Nitrox (Mix 1) and the rela­ting icon ( ), or the icon ( ) in case of an air dive. By
keeping the button depressed, the computer will display the
second mixture’s parameters (if set) in alternative sequel, and
then return to those of the primary.

Related topics:

• 2.3.1. - program parameters setting

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

2.4. - program parameters setting (deptho­meter/timer)

The Archimedes II computer is equipped with a third program
( program or depth meter/timer) that may be used for
both apnea (free divers) divers and for the use in technical
dives with helium-based binary and ternary mixtures. In this
case, the instrument gives only the dive’s basic depth and dive
time parameters. It does not make tissue saturation and de­saturation computation, which must be programmed and
computed by means of proper software and/or tables.

Cressi-sub reminds you that sport dives must be carried out
within the no-decompression guidelines, and at the maximum
depth of 132 ft. This is the limit of sport diving. To exceed these
limits remarkably increases the risk of decompression sickness.

169

ENGLISH

WARNING: Archimedes II Cressi-sub computer has been

i

i

developed for sport diving use only. It is not intended for
commercial or professional use requiring longer dive times
and greater depths. Diving beyond the parameters of sport
diving dramatically increases the risk of decompression
sickness.

DANGER: Cressi-sub discourages diving with



gaseous mixtures other than air without proper training.
The use of “
diver to different risks than those of sport diving, including
serious physical damages and, in extreme cases, death.

WARNING: After a dive with Archimedes II set in
not make saturation and de-saturation computa-

tions during the following 48 hours.

technical

mod. (depth meter-timer). The instrument will

” multi-gas mixtures may expose the

 DANGER: Should you decide to reset the instrument

by depressing button RESET on the back of the computer,
the nitrogen memory will be cancelled; therefore; the
instrument will not be able to compute a following dive.
Never use this function for at least 48 hours after the last
diving activity.

To go to program depress button B until the menu
is shown, then depress button C, which you may choose
Archimedes II DIVE/GAGE programs (Picture 7).

NOTE: Archimedes II computer is set at the factory on

gram to be used.
In program, the INFO, PLAN and SIMU functions are swit-

program.

program will remain set until the diver changes the pro-

ched off, while it is possible to set only a maximum depth
alarm which may be switched on or off by the user by setting
the instrument, following the same procedures shown in
chapter 2.5.1.

NOTE: In function the depth indicator gives indica-
tions between 0 – 655.8 ft..

Related topics:

• 2.5.1. – Maximum depth alarm.

• 3.6. – program (depthometer/timer)

2.5. - Instrument general setting.

2.5.1. - Maximum depth alarm

Archimedes II computer is equipped with a maximum depth
alarm preset at the factory (picture 8 a) on a value of 132 ft.
This is the limit of sport dives. When the function is on (ON)
(picture 8b), upon reaching the set maximum depth a sound
alarm will start and the display will flash for three seconds.
It is possible to switch on the alarm, or modify the maximum
depth, by depressing button B, then button A ( ), selecting,
in the following order, the dive’s parameters relating to:

PO2 Mix 1 -> FO2 Mix 1 -> PO2 Mix 2 -> FO2 Mix 2

-> Safety Factor -> Max Depth -> OFF/ON

While in Max Depth menu (picture 8 a), you may modify the
value of maximum depth from 0 – 325 ft., by depressing but­ton C ( ). When you have set the desired depth, depress but­ton A ( ) in order to switch on or off the depth alarm by means
of button C ( ). The computer is set at the factory on the
values of 132 ft. and OFF . Depressing button B (Mode) for seve­ral seconds will return back to the normal display (picture 1).

170

NOTE: When switched on (ON), the maximum depth

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alarm works in both and computing programs.
Related topics:

• 2.3.1. – parameters setting.

• 2.4. – program (depthometer/timer)

2.5.2. - Date and time adjustment ( ).

To adjust date and hour, depress button B (Mode) until the
icon ( ) appears on the UFDS display, with the seconds’
display flashing (picture 9).
By depressing button A ( ) view the regulation of (picture

9). 1) second, 2) minutes, 3) hour, 4) 12/24h and, in sequen­ce, year, month and day. By depressing button A ( ), the
function to be modified will flash and may be varied by
depressing button C ( ).

To revert back to the normal display (picture 1), depress but­ton B (Mode) for several seconds.

NOTE: Always check the hour and date in order to get
correct entries in your computer’s logbook.

Related topics:

• 4.1.2. – Logbook.

• 3.6. – program (depthometer/timer)

2.5.3. - Units of measure setting.

Archimedes II computer can make computations by metric
units (depth in meters and temperature in °C), or in feet and
(depth in feet and temperature in °F).

To change the units of measure to be used, depress button

B (Mode) to go to the first menu of ( or ) program
setting (picture 3). Then depress buttons A+C in sequence
and keep them pressed together for about 5 seconds. An
alarm and the new set unit of measure will appear on the
display.
By depressing button B (Mode) for several seconds, you will
return to the normal display (picture 1).

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ENGLISH

Foto Ghisotti

3) While diving

3) While diving

3. - program.

Archimedes II computer offers two computing pro­grams; for air ( program) and for nitrox mixtures or
EAN (Enriched Air Nitrox) dives. Archimedes II allows for use
with up to two different nitrox mixtures during the same dive.

NOTE: Archimedes II computer is set at the factory on
program, with the primary mixture’s (Mix 1) O2
value on 21% and PO2 on 1.4. The second mixture (Mix

2) is set at the factory off. Each manual variation of the
manufacturer’s values relating to Air program will start
Archimedes II Nitrox computation program.

3.1. - AIR DIVE.

Archimedes II computer starts automatically the "Dive" pro­gram at a depth superior to (ft. 5). During a curve dive the
display will show the following information (picture 10):

1 current depth value, in meters (m) or feet (ft.)

2 no decompression time still available is shown by the

“NDL” - (No Decompression Limit) icon

3 maximum depth reached during the dive

displayed in meters (m) or in feet (ft.), shown by the
“MAX” icon

4 time spent diving, shown by the "DIVE T" icon

indicator of segmented surfacing speed

5
6 graph of nitrogen amount absorbed during the dive
7 graph representing CNS O2 toxicity level (see chapter

3.3.4)

8 Automatic indicator of altitude level

9 Icon of maximum depth alarm (if switched ON – see 2.5.1)
10 indicator of Nitrox mixture(s) dive
11 MIX1 or MIX2 icons identifies which Nitrox mixture is being

considered by the computer to make its computations

12 ( ) and ( ) icons, that is “Info” (button A) and back-illu-

mination (button C).

Further important information are obtained by keeping pres­sed button A ( ) during the dive, that is (picture 11):

1 current PO2;
2 oxygen percentage of the selected mixture (Air if FO2=21%);
3 maximum depth reached during the dive, in meters (m) or

feet (ft.);

4 current temperature, expressed in °C or °F

The UFDS display show ( ).

NOTE: When the computer is used for air dives, it is not
necessary to carry out any FO2 change or setting before
the following dive.

During your diving activity, light condition may not allow easy
reading of the display, therefore, it is possible to switch on its
back-illumination by depressing button C ( ). The display’s
back-illumination will last about 5 seconds and may be repea­ted any time you want. The battery consumption is minimal
when the back-illumination is activated.

Related topics:

• 2.3. – Dive parameters setting

• 3.4.1. – Ascent rate.

• 3.3.3. - Mixture changing by diving

• 3.3.4 - CNS toxicity display.

• 3.3.5. - PO2 alarm.

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ENGLISH

i

3.2. - HYPER-OXYGENATED (NITROX) MIXTURES
DIVE

3.2.1. - Before a Nitrox dive.

 DANGER: the use of the computer with hyper-oxyge-

nated (Nitrox) mixtures is exclusively intended for divers
who have attended a full training course on the use of
such mixtures.

The Nitrox program for Archimedes II computer allows
making saturation and de-saturation computations for a dive
by using up to two different nitrox mixtures and is switched on
any time the parameters of program the primary
mixture FO2 on Mix1=21% and second mixture Mix2=off, are
changed. In this case the display will show (Nitrox) icon (pictu­re 12) which will stay on during the dive and until Archimedes II
remains set on Nitrox parameters.
Once Nitrox program is on, it is necessary to set Archimedes II
computer with the exact values of oxygen percentage (FO2)
contained in the cylinders to be used during the dive, after
having analyzed their content, so the computer is able to adapt
its computing algorithm according to the new set parameters.

WARNING: Archimedes II computer always keeps
sets it for the use with Nitrox mixtures (chapter 2.3.1– Dive

parameters setting)

DANGER: Do not dive with cylinders containing Nitrox



mixtures without checking their oxygen percentage.

program switched on for air dives, until the diver

WARNING: Before diving, always check the oxygen per­centage of the mixture(s) set on the computer. This is done
on surface by depressing button A ( ) which allows visua­lization of the previously set parameters.

WARNING: Under the same dive conditions, a Nitrox mix­ture requires longer no decompression times than air. It is
recommended to comply with the maximum depth allowed
by the selected Nitrox mixture.

Related topics:

• 2.3.1. - parameters setting.

• 2.3.3. - Rapid visualization of set data.

• 3.3. - Nitrox parameters setting.

• 3.3.3. - Mixture changing by diving.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarm.

3.3. - Nitrox parameters setting.

3.3.1. - Partial pressure setting (PO2).

Archimedes II is set at the factory on a basic PO2 value of 1.4
bar for both mixtures of Nitrox and air dives, in order to gua­rantee the maximum safety during dives.

It is possible to modify the PO2 setting on values between 1.0
bar and 1.6 bar. Should you elect to increase the dive’s margin
of safety, it is possible to set PO2 on lower values, down to a
minimum of 1.0 bar. It is explained in paragraph 2.3. how to
carry out the selection of values. To do so, depress the central
button B (Mode) to the ( ) menu, shown in picture 3, and
the parameters will be modified according to the following
scheme: by depressing button A ( ) it is possible to select, in

174

the following order, the dive parameters relating to:

i

i

i

PO2 Mix 1 -> FO2 Mix 1 -> PO2 Mix 2 -> FO2 Mix 2

-> Safety Factor -> Max Depth -> OFF/ON

where PO2 Mix 1 is the oxygen’s partial pressure of the primary
mixture (MIX1), which the diver may set, as already shown, on
values between 1.0 bar and 1.6 bar, by variations of 0.1 bar. The
same may be done for the second mixture’s (Mix 2) PO2. By
depressing button A ( ) the chosen setting is confirmed.
To return to the normal display depress button B (Mode) for
several seconds (picture 1).

WARNING: The computer keeps the PO2 setting on, until
the diver manually resets it to different values.

Related topics:

• 2.3.1. - Dive parameters setting

• 3.3.3. - Mixture changing by diving.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarm

3.3.2. - Nitrox mixture(s) oxygen fraction FO2 setting.

WARNING: Check the FO2 value set on the computer prior

to diving!

In order to set the correct oxygen percentage contained in the
Nitrox mixture(s), depress the central button B (Mode) to the
(DIVE) menu, as shown in picture 3, where the parameters may be
modified according to the following scheme: by depressing button
A ( ) it is possible to select the dive parameters relating to:

PO2 Mix 1 -> FO2 Mix 1 -> PO2 Mix 2 -> FO2 Mix 2

-> Safety Factor -> Max Depth -> OFF/ON

where FO2 Mix 1 is the oxygen percentage of Nitrox primary
mixture (MIX1), which can be set on values between 21% and
50%, by O2 variations of 1%. The second mixture’s FO2 (FO2
Mix2) can be set to values between 21% and 99%, by O2 varia­tions of 1%. This is done by depressing and keeping button C
( ) depressed.

NOTE: By keeping button C ( ) depressed, the computer
automatically stops on the value of the first of the two standard
Nitrox mixtures (EAN 32), corresponding to 32% oxygen.

NOTE: By varying the oxygen mixture percentage, the
computer will display the maximum depth (MAX) that may

be reached with that mixture.
This depth varies according to the set PO2.
Depress button C ( ) to manually set percentages of other

mixtures different from the standard ones.
Depress button A ( ) in order to confirm the desired percen-

tage, which will appear on the display.
Depress button B (Mode) for several seconds to return to

the normal display (picture 1).

NOTE: It is possible to modify the Nitrox mixture(s) setting

even during the surface interval (

gress

) (Picture 12a).

This feature is important, especially for divers who carry out a
series of subsequent dives; it allows the modification of one
mixture after having carried out a first air dive without having
to wait until full de-saturation.

175

with de-saturation in pro-

ENGLISH

It is important to comply with and understand the following:

1 At the end of a dive, the previously set mixture(s) oxygen

only

percentage FO2 will be stored in the memory

during
the first ten minutes of the surface interval. Should
another dive be carried out within this period of time, it will
be interpreted by the computer as a continuation of the
previous dive.

NOTE: It is not possible to go to program within the
first 10 minutes after having ended a dive.

NOTE: It is NOT possible to set any variation of the mixture(s)
FO2 within the first 10 minutes after having ended a dive.

Additionally, it is not possible to get to the (DIVE) parameters
setting menu and therefore to modify the previously set per­centage, within the first 10 minutes of surface interval.

2 10 minutes after the completion of the dive, the computer

resets the FO2 percentage/s on a safety value of 99%, wai­ting for the user to set the correct value relating to the new
mixture(s). The display will show "--" as in (picture 12b).

The diver must analyze the following dive’s mixture and set
the new FO2 value on the computer.

Should you neglect to set the new FO2 value on the compu­ter, you would be warned by the PO2 alarm (picture 13), at a
depth of m 4 (ft. 13) (toxicity limit of a EAN 99 mixture, with
P02 value set on 1.4), the FO2 automatically resets the O2
limit value of 99%. This is done to warn the diver and correc­tly reset his dive’s parameters, by surfacing at once. Should
the dive be continued, a second PO2 alarm at 1.6 bar (that is
at 20 ft.) would start.

3 Should the FO2 value be set and no dive carried out, the

computer will store the set value in the memory until the
current day’s midnight, when it will reset it on 99%
(picture 12b)

Related topics:

• 2.3.1. - parameters setting

• 3.3.1. - PO2 setting

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms

• 4.1.1. - Surface interval.

3.3.3. - Mixture changing while diving.

Archimedes II computer can make computations relating to
the saturation and de-saturation of a dive carried out using up
to two nitrox mixtures. In the previous chapters, it has been
shown how to set the basic PO2 and FO2 parameters of the
primary mixture MIX1 and the (possible) second mixture
MIX2, before the dive.

NOTE: Archimedes II computer

always

starts the computa-

tions relating to the dive on the primary mixture MIX 1.
While diving, it is possible to change from the primary mixtu-

re MIX1 to the second mixture MIX2, by depressing button
B for more than 5 seconds, until the icon of the new mixtu­re stops flashing. At this point, the mixture change will be
shown by the new value, shown by the MIX2 icon, on the
UFDS display (pictures 14a and 14b).
The same procedure may be used to carry out the opposi­te change; this will change to the primary mixture MIX1,
when the computer is set on the second mixture MIX2.

176

 DANGER: As a safety measure, in order to avoid the

i

involuntary setting of nitrox mixtures at depths where they
might be toxic (excessive PO2), Archimedes II does not
allow the mixture change if the new mixture’s PO2 is higher
than the one set on the computer (1.4 bar = default value).
The maximum PO2 alarm will sound if you attempt to set
nitrox mixtures at depth.

DANGER: Should both mixtures’ FO2 values be set and



no dive carried out, the computer will store the set values in
the memory until the current day’s midnight, when they
both will be reset on a value of 99%.

 DANGER: After 10 minutes from the end of a dive, the

computer resets the mixtures’ FO2 on a safety value of
99%, waiting for the user to set the correct values relating to
the new mixtures. The display will show "--" in the place of
FO2%, as in (picture 12b).

 DANGER: Always check, prior to diving, the FO2 and

PO2 values of both set mixtures! While on the surface, it is
possible to check their values, by depressing button A ( ),
which visualizes the previously set parameters.

 DANGER: do not dive with bottles containing Nitrox

mixtures, without having personally checked their oxygen
percentage.

Related topics:

• 2.3.1. - program parameters setting

• 3.3.1. - PO2 setting

• 3.3.2. - Nitrox mixture/s oxygen fraction F02 setting

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms.

3.3.4. - CNS toxicity display

Archimedes II computer is display a graph of the Central
Nervous System toxicity level as to the oxygen level. Its toxi­city level is bound with the oxygen’s partial pressure and
with the exposure to high oxygen partial pressures (PO2).
Picture 15 represents the UFDS display’s 8 pixels column,
which shows the increasing accumulated oxygen quanti­ties. When all 8 pixels light up, 100% of the maximum tole­rance allowable to the CNS has occurred and serious dan­ger of an oxygen intoxication exists.

It is important to understand, monitor, and control the oxy­gen toxicity level.

In order to reduce the risk of oxygen toxicity, ArchimedesII
displays a graph which is easy to be read in any situation.
When the oxygen level reaches warning values, next to the
maximum allowable toxicity (corresponding to 7 of 8 lighted
pixels), the graph starts flashing along with the display, and
an alarm starts sounding which lasts 15 seconds, showing
the proximity of a CNS toxicity level.

When the eighth pixel lights up, a second (100%) alarm
starts sounding. At this time the graph and display flash and
the alarm sounds, until the diver surfaces, letting the oxygen
partial pressure decrease.

When the eighth pixel turns off and the graph stops flashing,
the alarm will be entered in the Logbook.

177

ENGLISH

NOTE: The result of the computation is the oxygen compo-

sition is approximated to the nearest whole number.
NOTE: The computation of CNS toxicity shown by the rela-

ting graph, takes into account both mixtures used during the
dive. By using highly nitrox mixtures during the decompres­sion, the toxicity level may be reached during the final phase
of the dive. In this case, the alarm will sound after the seventh
pixel has lit up; the diver must quickly change over to the bot­tom mixture and the computer must be consequently reset.

DANGER: Do not use nitrox mixtures during diving acti-



vities without proper training by certified training agencies.

Related topics:

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

• 3.3.1. - PO2 partial pressure setting..

• 3.3.2. - Oxygen fraction FO2 setting.

• 3.3.5. - PO2 alarms.

• 4.1.2. - Logbook.

3.3.5. - PO2 alarm.

Archimedes II computer is able to constantly monitor
another basic parameter relating to oxygen, and that is O2
partial pressure value (PO2). Oxygen toxicity may be caused
both by an excessive accumulation (CNS toxicity, seen in the
previous chapter) and by exceeding the maximum PO2,
which is exceeding the maximum depth allowed by the mix­ture used. As already seen, the PO2 limit value is set by the
diver in a range between 1.0 bar and 1.6 bar. Archimedes II
considers the 1.6 bar value as the partial pressure maximum
allowable limit and, according to the used mixture, automati-

cally signals the maximum depth which may be reached.
Remember that even by using air, you may reach the oxygen
toxicity limit. Such limit varies according to the set PO2.
Archimedes II is manufactured with a preset value of 1.4 bar,
whose corresponding maximum depth is 1834 ft. in air. It is
possible to set the computer on other PO2 values, up to a
maximum of 1.6 bar. Archimedes II is equipped with two
kinds of PO2 alarms:

1 By reaching the limit depth relating to the set PO2 (from

1.0 bar to 1.6 bar), a sound alarm will start lasting 15
seconds while the display will be flashing, showing the
( ) icon and the reached PO2 limit value, at the top on
the left (picture 16).

2 A second alarm will start by achieving the depth equiva-

lent to PO2 of 1.6 bar and will last 15 seconds. The display
will be flashing and will stop only when the diver will reach
a depth lower than the limit one.

Both alarms will be entered in the Logbook.

Related topics:

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

• 3.3.1. - PO2 partial pressure setting.

• 4.1.2. - Logbook.

3.4. - Curve dive.

3.4.1. – Ascent rate.

Archimedes II Cressi-sub computer’s algorithm considers
different ascent rates according to the depth. The speed is

178

shown on the display by a segmented indicator at the bottom
on the right, which functions according to following table:

Depth
0ft

19,7ft
59ft







19.3ft

58.7ft
5ft

No segment

0.0 ft -

12.8 f/min

0.0 ft -

19.3 ft/min

0.0 m -

25.9 ft/min

1 segment

13.1 ft/min -

19.3 ft/min

19.7 ft/min -

25.9 ft/min

26.2 ft/min ­36 ft/min

2 segments

19.7 ft/min -

25.9 ft/min

26.2 ft/min ­39 ft/min

39.4 ft/min -

52.1 ft/min

3 segments

26.2 ft/min
()

39.4 ft/min
()

52.4 ft/min
()

If, during surfacing, the maximum allowed ascent rates are
exceeded, the display will show different segments, showing
the ascent rate increasing level. Additionally, the alarm will
sound, the UFDS display will start flashing ( ) icon (picture

17), as well as the flashing segmented ascent rate and cur­rent depth value indicator.
In this situation, surfacing must be stopped until the ( ) icon
disappears and the computer shows its normal display.

 DANGER: Surfacing too fast dramatically increases the

risk of air embolism. Cressi-sub recommends that at the
end of each dive, engage in a "safety stop" of 3-5 minutes
at 10 ft– 20 ft., which will be assisted by the computer (see
chapter 3.4.2

WARNING: Do not engage in a follow up dive after a surfa­ce interval if the ( ) icon has been on! The computations
for the next dive might be invalidated by exceeding the maxi­mum ascent rate.

Related topics:

• 2.5.3. - Units of measure setting.

• 3.4.2. - Safety stop.

• 4.1.2. - Logbook.

3.4.2. – Safety Stop ( ).

Archimedes II is automatically programmed to signal a safety
stop after each dive at a greater depth than 32 ft., as recom­mended by training agencies and the most recent studies on
diving physiology. A stop should be carried out at a depth
between 10 ft – 20 ft., and to last as long as signalled by the
computer.

NOTE: Cressi-sub recommends that after each dive, a safety
stop of 3-5 minutes at 10 – 20 ft be conducted.

The stop is indicated on the display by the ( ) icon (pic­ture 18); on such occasion, the display indicates how many
minutes the stop must last and the depth at which it has to be
conducted.
Although the safety stop is not mandatory, they are highly
recommended. In the event that ascent rates have been
exceeded, additional safety times should be conducted.

DANGER: It is very important that ascent rates be care-



fully monitored after a safety stop. Rapid ascent rates, after
a safety stop, are very dangerous and can result in air
embolism.

Related topics:

• 2.5.3. - Units of measure setting.

• 3.4.1. - Surfacing speed.

3.4.3. – Decompression forewarning.

Any time the available no decompression time shown by the
“ ” display decreases to 3 minutes (picture 19), Archimedes
II will engage an alarm and the display flashes for several
seconds notifying the diver that they are approaching no

179

ENGLISH

decompression limits, therefore beginning a decompression
requirement.

Related topics:

• 3.5. - Decompression dive.

3.5. – Decompression dive ( ).

5 “DIVE. T” icon giving the total time spent while diving.
6 Graph showing the nitrogen absorbed during the dive: in

this case it is fully lit up until next “DECO” icon.

DANGER: DO NOT surface above a decompression



depth.

 DANGER: Do not use this instrument to dive beyond

the no decompression limits! Cressi-sub discourages the
use of this instrument for decompression dives.

In the event that you have exceeded the no decompression
limits, your Archimedes II computer will assist with specific
information related to surfacing and related decompression
information. Upon violating the no decompression limits, the
computer will sound an alarm lasting several seconds, and
the display changes as in picture 20 , giving the diver the fol­lowing information:

1 ( ) replaces “NDL” icon on the UFDS display, showing

that no decompression has been violated and decom­pression stops must be taken.

2 Depth of first decompression stage (the deepest), given

in meters (m) or feet (ft.). It may vary from a maximum of
98 ft. to a minimum of 10 ft., by decreases in increments

of 10 ft..
3 Time in minutes for first decompression stage (the deepest).
4 (TOTAL) icon informs the total surfacing time which inclu-

ded all decompression stops and proper ascent rates

between stops and from the last stop to the surface.

To avoid ascending to a depth above the decompression
depth, you should ascend to a depth slightly deeper than
the stage decompression depth requirement.

You should consider the amount of gas needed to succes­sfully complete all decompression requirements.

During rough sea conditions, it may be difficult to comply
with the decompression stage requirements without
exceeding them. Cressi-sub recommends that shallowest
depth (nearest the surface) be at depth of about 13–16 ft.,
even though decompression will take slightly longer.
Archimedes II will automatically calculate this.

Related topics:

• 2.5.3. - Units of measure setting.

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

• 3.4.1. - Ascent rate.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms.

• 4.1.2. - Logbook.

180

3.5.1. – Omitted Decompression stage alarm.

If the decompression stage is missed by surfacing above the
depth given by the computer, an alarm will sound and the
display will flash until the diver descends back to the proper
depth (ceiling) or below it (picture 21).
The computer allows a maximum time of 3 minutes to cor­rect this dangerous situation; during this time, the alarm will
continuing sounding. In the event that the diver does not
descend to the proper depth (after 3 minuets) the computer
display “Error” program and won’t be usable for the next 48
hours. The only functions working will be Logbook/Profile and
History.

 DANGER: Should this happen, you must not dive for the

next 48 hours.

In the event that you feel any symptoms of decompression
sickness or air embolism, you should contact emergency
medical services as available in your area. Additionally, DAN
(Divers Alert Network) or your local hyperbaric chamber cen­ter should be contacted.

Related topisc

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

• 3.5. - Decompression dive.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms.

• 4.1.2. - Logbook.

3.6. – program (depthometer/timer).

Archimedes II computer is equipped with a third dive com­puting program ( program). This function is especially

useful for apnea (free diving) divers as well as for technical
dives with helium-based binary and ternary mixtures. Please
be advised that Archimedes II in program mode does
compute any saturation and de-saturation computations. It
functions only as a basic instrument offering depth and time
functions. During a dive conducted using the Gage mode,
proper decompression software must be utilized according
to proper dive tables.
Cressi-sub reminds you that sport dives must be carried out
within the no decompression guidelines, and at the maximum
depth of 132 ft., which is the limit of
such limits dramatically increases the risk of decompression
sickness!

WARNING: Archimedes II computer has been developed
for sport diving only. It is not intended for commercial or pro­fessional use requiring longer dive times, and greater diving
depths. Diving beyond the parameters of sport diving dra­matically increases the risk of decompression sickness.

DANGER: Cressi-sub discourages diving with gaseous



mixtures other than air without proper training. The use of
“technical” multi-gas mixtures may expose the diver to dif­ferent risks than those of sport diving, including serious phy­sical damages and, in extreme cases, death.

Archimedes II computer’s diving program starts the
depth meter/timer functions automatically at depths deeper
than 5.0 ft., showing the following information on its display
(picture 22):

1 current depth value, in meters (m) or feet (ft.). The depth

meter’s operative range reaches a depth of m 199.9 (ft.

656).

181

sport

diving: to exceed

ENGLISH

2 dive time, shown by the “DIVE T" icon, given by the timer

i

in minutes and seconds.

3 maximum depth reached during the dive

given in meters (m) or feet (ft.), shown by the

“MAX” icon.

4 segmented ascent rate indicator
5 icon of maximum depth alarm (if ON – please see 2.5.1)
6 computing program icon
Additional important information may be obtained by depres-

sing button A ( ) depressed during the dive, representing (pic­ture 23):

1 Maximum depth reached during the dive, given in meters

(m) or feet (ft.);

2 Current temperature, expressed in °C or °F ;

by keeping button B depressed it is possible to read the

time in hours and minutes. The UFDS display will show

( ) (picture 24).

WARNING: The computer will not compute any saturation
and de-saturation computation during the remaining 48
hours elapsing from the end of the program dive.

 DANGER: Should you decide to reset the instrument by

pressing button RESET on the computer’s back, the nitro­gen memory will be cancelled. Therefore, the instrument will
not be able to compute a following dive. Never use this
function at least 48 hours after the last diving activity.

Related topics:

• 2.4. - program parameters setting (depthometer/timer)

• 2.3. - Parameters setting

• 2.5.1. - Maximum depth alarm

• 2.5.2. - Date and time adjustment

• 2.5.3. - Units of measure setting

• 4.1. - Data processing

• 4.1.1. - Surface interval ( , , )

• 4.1.2. - Logbook

182

4) On surface after a dive

4) On surface after a dive

Foto Ghisotti

ENGLISH

4.1. – Data processing.

This chapter deals with all the “on surface” functions, inclu­ding data processing after a dive, both in and in
programs. By depressing button B (Mode), it is possible to
track the following functions: ( )- logbook (please see
chapter 4.1.2.). ( ) – dive history memory (please see

4.1.3.). ( ) - Dive profile (please see chapter 4.1.4.). Data
PC transfer by means of the interface (optional) (please see
chapter 4.1.5.).

4.1.1. – Surface interval.

After a dive in program (a depth greater than 5 ft.), the
UFDS display will offer the following information (picture 25):

1 De-saturation time, given in hours and minutes by the

( ) icon;

2 “Don’t Fly” ( ) icon.
If the “Don’t Fly” icon is displayed, flights or travel to higher alti-

tudes than the current altitude must be avoided, so long as it
is visible on the display.

WARNING: DAN (Divers Alert Network) and UHMS
(Undersea and Hyperbaric Medical Society) advise a surfa­ce interval time of between 12 and 24 hours for no decom­pression dives, and a surface interval of 48 hours after a
decompression dive or especially fatiguing dives.

3 Surface time ( ), displayed in hours and minutes,

means the current surface interval time.

4 graph showing the tissues residual nitrogen after the dive.

NOTE: Should a dive begin with less than 10 minutes of sur­face interval time, Archimedes II will consider this a conti­nuation of the previous dive; the dive’s count and dive time
computation will restart from where they had stopped.

NOTE: Dives carried out after at least 10 minutes of surfa­ce are considered as a new dive.

Should the dive be carried out in or depth meter/timer
program, the computer will not supply any data relating to
de-saturation and will process any saturation and de-satura­tion computations during the following 48 hours elapsing
from the program dive. They are given by the surface
time (SURF T) icon, in hours and minutes, which indicates the
current surface time (picture 26).

By depressing button B (Mode) twice, you view to the dive
planning program, represented on the UFDS display by
( ) icon (picture 5b), as seen in chapter 2.4. It will take
into account the residual tissues’ nitrogen, and will modify the
no decompression time, making them shorter than those
given for the first dive.

NOTE: PLAN function does not function in compu-
ting program (depth meter/ timer).

At the end of de-saturation, the lateral bar, representing the
residual nitrogen, will be empty, representing the full elimina­tion of residual nitrogen that may affect following dives.

Related topics:

• 2.3.2. - Dive planning.

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES icon.

184

4.1.2. – Logbook ( ).

Archimedes II computer memorizes data relating to the last
30 hours’ dives (or to the last 60 dives) both in and

programs. The data is entered every 30 seconds into
the Logbook (dive journal). This may be activated on the sur­face by repeatedly depressing button B (Mode), until the
(LOG) icon appears on the UFDS display (picture 27).

NOTE: Dives lasting less than 30 seconds (data entering
interval) will not be memorized.

Archimedes II logbook is a multifunction instrument that can
be viewed on three different display modes. A full range of
information relating to the dives starts with the most recent
dive in chronological order.

The normal UFDS display shows the function, and the
following information is given:

1 Dive’s year

2 Dives’ date (month and day)

NOTE: The first of the daily dive series’ is given in brackets
with 1 (as dive 1), the second with 2 (dive 2), and so on.

3 Maximum depth reached during the dive, given in meters

or feet.

4 Dives’ number: the most recent dive’s information are

given first. When more than 60 dives are carried out, the
oldest dives are cancelled out.

5 Graph of the residual nitrogen at the end of the dive in

program. Should the dive be inside the “green” it is

classified a no decompression dive. Should it enter the
“red” zone, it is classified a decompression dive.

6 Indicator of altitude level at which the dive has been car-

ried out (see chapter 2.2.).

7 The ( ) icon will appear when an EAN x (Nitrox) mix-

ture dive has been carried out in program.

8 Indicator of CNS O2 toxicity at the end of the dive in

program ( see chapter. 3.3.4).

All three display modes show the icons relating to the alarms
which may have engaged during the dive. These icons would
display as follows:

( ) (PO2) alarm; ( ) (maximum surfacing depth alarm)
and so on.

To view the second logbook display mode, depress button C
( ) on the UFDS display. The ( ) icon is replaced by the
dive’s number, followed by the second logbook display
mode. It displays the following information (picture 28):

1 Dive’s starting hour (the hour at which the computer has

gone below 5 ft.), and the function relating to the set
computing program ("DIVE" o “GAGE”) has started;

2 Dive’s end hour (the hour at which the computer has

gone below 5. ft).
3 Dive’s average depth (AVE) in meters or feet.
4 Dive’s total time, given in minutes by the "DIVE T." icon.
To return to the first display mode, depress button A ( ). To

view the third logbook display mode, depress button B ( )

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ENGLISH

on the UFDS display. The second display mode giving the
dive’s number followed by (…-2) will be replaced by the dive’s
number followed by “…-3”, that is, the third logbook display
mode, which displays the following information (picture 29):

1 Mixture used for the dive in program: if an air dive,

( ) will appear, if a Nitrox mixture dive, the display FO2
and the icon relating to the given mixture (MIX1 or MIX2),
automatically alternating both values, starting from the pri­mary one (pictures 30 a – b)

NOTE: Should the second Nitrox mixture MIX2 not be set,
the computer will give only the FO2 value of the primary
mixture.

2 Water temperature recorded during the dive at the maxi-

mum depth, given in °C or °F.
3 Surface interval given in hours and minutes.
4 The use of a safety factor (SF1/2) during a dive in

program.
To view the previous dive recorded in the logbook, depress

and hold button C ( ); in a rapid sequence you can view to
the first logbook display mode relating to the previous dive.

By depressing and holding button A ( ), you will enter into a
rapid sequence to the first logbook display mode relating to
the immediately subsequent dive.

Relating topics:

• 2.3.1. - program parameters setting.

• 2.5.3. - Units of measure setting.

• 2.5.2. - Date and hour adjustment.

• 3.1. - AIR DIVE.

• 3.4.1. - Ascent rate.

• 3.2. - NITROX mixtures dive.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms.

• 3.6. - program.

• 4.1.1. - Surface interval.

4.1.3. – Dive historic memory ( ).

Archimedes II computer is equipped with a dive history
memory for both and program dives; this is the
( ) function. In order view this function, depress repea­tedly button B (Mode), until the ( ) icon appears on the
UFDS display UFDS (picture 31). The program will display the
following information:

1 total time of all dives carried out, in hours;
2 maximum depth reached during all dives (given in meters

or feet);

3 total number of dives, given by the “DIVE” icon.
The ( ) function is able to store up to 999 dives, after

which it will cancel the memory and restart from zero. This
value may be modified by means of the (optional) interface
software.

Related topics:

• 2.5.3. - Units of measure setting.

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

• 4.1.5. - Data PC transfer: compatible PC interface.

186

4.1.4. – Dive profile ( ).

The dives’ detailed profile carried out in both and
programs and stored in the logbook’s memory, is entered by
repeatedly depressing button B (Mode), until the ( ) icon
appears on the UFDS display (picture 32). The display will
automatically show any information relating to depth, time
and decompression of the most recent dive stored in the log­book, therefore allowing to scan the dive’s profile in detail,
even without the (optional) interface. The dive profile’s infor­mation will automatically appear with a 30 seconds’ interval
between each other. To view the immediately previous dive’s
profile depress button C ( ); to get to the immediately sub­sequent dive’s profile press button A ( ).

NOTE: The display will display all icons relating to the alarms
which have possibly engaged during the dive, like ( )
(PO2 alarm), ( ) (maximum surfacing speed alarm) and
so on.

Related topics:

• 2.5.2. - Date and hour adjustment.

• 2.5.3. - Units of measure setting.

• 3.1. - AIR DIVE.

• 3.2. - NITROX MIXTURES DIVE.

• 4.1.2. - Logbook.

• 4.1.5. - Data PC transfer: compatible PC interface.

4.1.5. – Data PC transfer: compatible PC interface.

Archimedes II computer may be interfaced with a PC having
following specifications:

• operating systems: Windows 98
Windows 2000, Windows ME, Windows XP (Windows is a
Microsoft Inc. registered trademark);

• CPU: Pentium II 266 Mhz or superior;

• RAM of at least 64 MB or superior (recommended);

• Video resolution: 800x600 or superior (recommended).

By connecting the Cressi-sub (optional) interface hardware
to a USB port and installing Cressi (optional) PC Logbook
software, it is possible to download any information stored in
Archimedes II to your PC. In order to do so, you must enter
into the Archimedes II “PC” function, by repeatedly depres­sing button B (Mode), until the ( ) icon appears (picture 33).

By following the directions, you can easily download your
own dives’ profile for viewing, printing or modifying by means
of the (optional) interface. This may be also used for training,
by means of a dive simulator contained in Cressi (optional)
PC Logbook software of its (optional) PC interface.

Related topics:

• 4.1.2. - Logbook.

• 4.1.3. - Dive historic memory.

• 4.1.4. - Dive profile.

second edition

,

187

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4.1.6. – Instrument reset.

The instrument may be completely reset, by depressing the
small button on the back of the instrument, shown as "RESET"
(picture 34). This will result in information relating to nitrogen
absorption and time/date to be cancelled.

fig. 34

WARNING: By resetting the instrument, all computations

relating to current de-saturation are cancelled! Do not
reset your instrument if it has to be used to compute sub­sequent dives!

NOTE: Dive logbook, profile and historic memory remain
stored in the memory even after the instrument’s reset.

The setting will revert back to the values set at the factory
(Dive Air program, that is FO2=21% and PO2=1.4 bar, maxi­mum depth alarm on m 40 (ft. 132), not working).

Such function may be especially useful in case of instrument’s
renting by Diving Centres.

Related topics:

• 2.3.1. - program parameters setting.

• 2.5.2. - Date and hour adjustment.

• 4.1.1. - Surface interval.

• 4.1.2. - Logbook.

• 4.1.3. - Dive historic memory.

• 4.1.4. - Dive profile.

4.2. – Simulator.

4.2.1. – DIVE simulator program ( )

Archimedes II is equipped with a simulator program ( ),
which allows the diver to become acquainted with the com­puter’s different functions. The simulator program allows per­sonal dives’ planning.

The program is entered by repeatedly depressing button B
(Mode), until the ( ) icon appears on the UFDS display
UFDS (picture 35): The display showing (possible) surface
interval starts flashing, waiting for a value to be set by the
diver. Depress button A ( ) to enter the simulation program

i

without surface interval, that is without data on residual nitro­gen, or depress button C to extend the surface time previous
to the simulated dive.

At this point, it is possible to simulate multi-levelled dives (pic­ture 36), by depressing button C ( ) to increase depth, or but­ton A ( ) to surface, by verifying in real time what the display
shows during the dive’s different stages, including both sound
and visible alarms. At the end of the simulated dive, the com­puter will give the relating surface and de-saturation time, and
it is possible to simulate the subsequent dive’s progress as
well. By depressing button B you view the display of subse-

188

quent dive’s simulation, with de-saturation in progress.

i

Should the simulation be carried out with Nitrox mixtures,
refer to all information seen in the chapters dealing with Nitrox
mixtures; it is possible to simulate the mixture change as well
as in reality, by depressing button B for more than 5 seconds
(picture 37).

If you want to reset the simulator, depress buttons A+C one
after the other during the simulation itself.

NOTE: The simulation is carried out with the dive para­meters set in (DIVE) function (see chapter 2.3.).

NOTE: The simulation is carried out at a speed six times
greater than the actual one. This equates to 10 seconds
on the simulator or the same as one real diving minute,
while the variations of depth are each m 2 (ft. 6).

Related topics:

• 2.3. - Parameters setting.

• 2.3.2. - Dive planning

• 3.1. - AIR DIVE.

• 3.4. - Curve dive.

• 3.5. - Decompression dive.

• 3.2. - NITROX MIXTURES DIVE.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms.

• 4.1.1. - Surface interval.

• 4.2.2. - Surface interval dive simulator.

4.2.2. – Surface interval dive simulator.

Should the computer contain residual nitrogen (de-saturation
time is still in progress), Archimedes II allows modifying of the

surface interval in order to simulate a subsequent dive. As
noted in the previous chapter, the simulator program is ente­red by repeatedly depressing button B (Mode), until the
( ) icon appears on the UFDS display (picture 35). The
display mode instructs you to set a new surface interval, by
means of UFDS display icons: by depressing button C ( ),
the surface interval will increase, while by depressing button
A ( ), the chosen value is confirmed. When this has been
done, Archimedes II will show the simulation display (pictu­re.36), as seen in the previous chapter, allowing you to simu­late a subsequent dive.

Related topics:

• 2.3. - Parameters setting.

• 2.3.2. - Dive planning

• 3.1. - AIR DIVE.

• 3.4. - Curve dive.

• 3.5. - Decompression dive.

• 3.2. - NITROX MIXTURES DIVE.

• 3.3.4. - CNS toxicity display.

• 3.3.5. - PO2 alarms.

• 4.1.1. - Surface interval.

• 4.2.2. - Surface interval dive simulator.

5. – CARE AND MAINTENANCE.

Archimedes II has been designed to operate in extreme con­ditions with extensive underwater use. You should remember
that it is a precision instrument deserving appropriate care.
Please avoid any violent shock, protect it from extreme heat
sources, always wash it in fresh water after using, dry it care­fully, do not store it wet, and avoid contact with heavy equip­ment, like diving cylinders.

189

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WARNING: Always wash the instrument in fresh water

after using.
NOTE: Please always wash the instrument in fresh water

after using.

The buttons do not need any particular care; never grease
them with oil or spray of any kind.

NOTE: Check the battery case housing compartment
through its transparent lid; should any signs of moisture be
visible, please have the instrument checked by an authori­zed Cressi-sub retailer.

Should you notice any possible anomaly in functioning, do not
use the instrument to dive and have it checked by an autho­rized Cressi-sub retailer.

Related topics:

• 5.1. - Battery replacement.

• 7. - Warranty.

5.1. – Battery replacement.

Replacing the battery is easily done by the consumer, not
requiring special service. It must be done any time the instru­ment’s display shows the run-down battery symbol, both
fixed and flashing (picture 2 a-b),as already seen in this
guide.

WARNING: By replacing the battery, all information rela­ting to de-saturation, time and date will be cancelled. Reset
the time and date, in order to get correct entries in your
computer’s logbook. Please do not replace the battery
when de-saturation is in progress, since all information rela-

ting to de-saturation computing would be cancelled. In this
case, please check the amount of de-saturation hours and
do not dive after battery replacement during a correspon­ding amount of hours. After battery replacement, all settings
go back to the values set at the factory (Dive Air program:
F02=21% and PO2=1.4 bar, maximum depth alarm on 132
ft., not working).

To replace battery, unscrew the transparent battery cover on
the back of the instrument by use of a coin (picture 38).
Remove the lid and check battery and its encasement. Should
you note traces of corrosion due to water entry, have the
instrument checked by an authorized Cressi-sub dive retailer.

If everything appears in good condition, remove battery by
holding the computer face down. Replace battery complying
with its polarity (note that an incorrect polarity will cause the
losing of information on calibre and memory!) and replace the
battery encasement’s lid as well (picture 39). The battery
encasement is watertight and is not connected to the instru­ment’s core; before closing the cover, check that there is no
soiling on it and apply a thin layer of silicone lubricant to the o­ring. (picture 40 a-b).

fig. 38

190

fig. 39

fig. 40 a

fig. 40 b

NOTE: Different factors affect the battery life. For exam-

ple: time of storage before acquiring the instrument, the
dive time, the use of back-illumination, the battery’s quality
and temperature.

NOTE: Do not over tighten the battery cover! Over tigh­tening of the cover does not create a better seal; to the
contrary, it can result in cracking of the cover or difficulty in
removing the cover in the future.

NOTE: Check the instrument’s hermetic sealing! The bat­tery’s lid is transparent, in order to allow the easy viewing
into the battery compartment.

WARNING: Any anomaly or water infiltration due to incor­rect battery replacement will void the warranty.

Related topics:

• 5. - Care and maintenance.

• 7. - Warranty.

6. – TECHNICAL SPECIFICATIONS.

Algorithm: Bühlmann ZH-L8
Standard fabrics: 12
Hemi-saturation time: from 5 to 640 minutes
Dimensions and weight: Diameter: 62 mm - Height: 24 mm -

Weight: 115 g

Depth sensor::

- Sea water setting (fresh water depths are

about 3% lower)

- Measuring field: 0-325 ft., measured every second

- GAGE function measuring field: 0-656 ft.

- Precision: +/- 1% (T 20°C – 68 F)

- Reading resolution: 0-328 ft.

- Surface interval: from 0 to 48 hours

- Altitude functions monitoring: from 0 to 19.684 ft., measured

every 10 minutes

- Dive time: from 0 to 999 minutes

- Data entering interval: 30 seconds

(it may be modified by means of (optional) interface program)

TERMOMETER:

- Resolution: 33 °F

- Measuring field: 23 °F + 104 °F

- Precision: +/- 35,6 °F/10min change °T

WATCH:

- Precision: +/- 30 seconds month average

- 24 hours display

BATTERY:

Li/MnO2 CR 2032 - 3V battery. 2 years average life (by 50
yearly dives)

191

ENGLISH

NOTE: Different factors affect the battery average life. For

example: the time of storage before acquiring the instru­ment, the dive time, the use of back-illumination, the bat­tery’s quality itself, whose average life varies according to
temperature.

6.1. – DECOMPRESSION TABLES

At the end of a dive, the computer will continue processing
data for a subsequent dive. This is possible since the compu­ter keeps recording nitrogen absorption of “standard” tis­sues, taken as reference. Each tissue absorbs and releases
nitrogen at different speeds, indicated by the so-called
“hemi-saturation times” (the time taken to reach a tissue 50%
saturation). Archimedes II uses 12 standard tissues, on which
the mathematical model computations are carried out, in any
stage of dive, surfacing and subsequent dives.

6.1.1. – No decompression tables by the first dive

in a series.

Depth

(m)

9
12
15
18
21
24
27
30
33
36
39
42
45
48

Depth

(ft)

30
40
50
60
70
80

90
100
110
120
130
140
150
160

AIR

200
104

66
47
35
25
19
16
13
11

EAN1 (32%)

(PO2=1.4bar)

200
200
117

74
55
41
32
24
19

-­9
8
7
7

--

--

--

--

EAN2 (36%)

(PO2=1.4bar)

200
200
182

92
65
50
38

--

--

--

--

--

--

--

192

7. – WARRANTY.

The Cressi-sub Archimedes II computer is warranted for
manufacturing materials and defects for a period of two years
from the purchase date. The warranty DOES NOT include
damages caused by improper use, by inattentive maintenan­ce or modifications/repairs carried out by unauthorized per­sonnel and is automatically suspended when the correct
maintenance procedures described by the present users’
guide are not followed. The warranty cannot be transferred by
the first purchaser to a third party. A purchase receipt (with
purchase date) from an authorized Cressi-sub dealer is requi­red for warranty service. Any unwarranted repairs will be car­ried out at the buyer’s expense.

The warranty does not include any document or warranty
granted by retailers or agents beyond the present warranty’s
terms.

No retailer or agent is authorized to carry out any variation to
the present warranty or to grant an additional one.

In the event of product malfunction occurring, contact your
authorized Cressi-sub retailer supplying your name and a
copy of the purchase receipt from a authorized Cressi-sub
dealer.

Please be advised the warranty is only valid if the Archimedes
II is purchased from an authorized Cressi-sub dealer.

Please always keep the present users’ guide for your
Archimedes II.

193

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195

196

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Cressi-sub S.p.A.

Via Gelasio Adamoli, 501 - 16165 - Genova - Italia

Tel. [phone] - Fax [phone]

E.mail: [e-mail]

WWW: http://www.cressi-sub.it