Nautilus DIVE PLANNER 1.0 User Manual

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User’s Guide

2959 Kiowa Blvd North

Lake Havasu City, AZ 86404

928-855-9400 (voice)

[e-mail]

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Copyright 2004, 2005 Tech Diving Limited All rights reserved

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English Edition

Version 1.0

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Important remarks concerning the manualImportant remarks concerning the manual

Important remarks concerning the manual

Important remarks concerning the manualImportant remarks concerning the manual

This manual makes use of the following icons to indicate especially important comments.

Indicates information about details which are important to prevent a risky situation.

Indicates a potentially hazardous situation which, if not avoided, could result in death or injury.

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By By

Joel D. Silverstein and R. Dan NafeJoel D. Silverstein and R. Dan Nafe

By

Joel D. Silverstein and R. Dan Nafe

By By

Joel D. Silverstein and R. Dan NafeJoel D. Silverstein and R. Dan Nafe

1st 1st

Edition, March, September 2005Edition, March, September 2005

1st

Edition, March, September 2005

1st 1st

Edition, March, September 2005Edition, March, September 2005

Copyright 2004, 2005 Tech Diving Limited - Scuba Training and Technology Inc. Joel D. Silverstein and R. Dan Nafe
No part of this publication may be reproduced without the express written permission of Scuba Training and Technology Inc.

NAUTILUS DIVE PLANNER is a product of Tech Diving Limited, a wholly owned subsidiary of Scuba Training and Technology Inc.
The program is written and designed by R. Dan Nafe and Joel D. Silverstein.

NAUTILUS DIVE PLANNER runs under Microsoft Windows 3.1, 3.11, 95, 98, NT, ME, XP, Windows is a registered trademark of the
Microsoft® Corporation. Mac OS 8.5, 9, X is a registered trademark of Apple Computer Inc., and Linux/X86 w/GTK. No representa-

tion is made to the complete compatibility of any hardware or software.

The names: NAUTILUS Dive Planner Software, Nautilus Dive Planner and Nautilus
are use interchangably throughout this manual and all result in the same meaning.

website: http://www.nautilusdiveplanner.com

e-mail [e-mail]

discussion group: http://groups.yahoo.com/group/nautilusdiveplanner/

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Special thanks to:

Hamilton Research Ltd. - R.W. Bill Hamilton, PhD & David Kenyon
National Oceanographic and Atmospheric Administration - David Dinsmore

Nautilus Dive Planner Software and this Manual are protected under copyright laws worldwide.
Specifications Subject to Change Without Notice -- Not Responsible for Typographical Errors.

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Important Remarks Concerning the Manual Page 2
Table of Contents Page 3
Important Safety Considerations Page 5
General Information Page 5

1 Product Overview

1.1 Nautilus Dive Planner Overview Page 6

1.2 Nautilus User Versions Page 7

1.3 Nautilus Function Tabs Page 7

1.3.1 Generate Profile Page 7

1.3.2 Gas Setup Page 8

1.3.3 Table Output Page 8

1.3.4 Compare Page 9

1.3.5 Manage Profiles Page 9

1.3.6 Formulary Page 9

1.3.7 Gas Mixing Page 9

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2 Screen Descriptions

2.1 Opening Screen Page 10

2.2 Preferences Page 11

2.2.1 Nautilus Standard Defaults Page 12

2.3 Gas Setup Page 13

2.4 Generate Profile Page 14

2.4.1 Create Single Square Profile Dive Page 14

2.4.2 Create a Multilevel Profile Dive Page 15

2.4.3 Creating Profiles Using Closed Circuit Page 16

2.4.4 Repetitive Dives Page 18

2.5 Manage Dives Page 19

2.6 Compare Page 20

2.7 Table Output Page 21

2.8 Formulary Page 22

2.9 Gas Mixing Page 22

2.10 Help Page 22

3 Nautilus Dive Planner Decompression Models Page 23

3.2 Buhlmann Model Overview Page 23

3.3 Hamilton-Kenyon Model Page 24

3.4 Variable Permeability Model (VPM) Page 26

3.5 4-Compartment Serial Model Page 28

3.6 Future Models and Integration Page 28

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Important SafetyImportant Safety

Important Safety

Important SafetyImportant Safety
ConsiderationsConsiderations

Considerations

ConsiderationsConsiderations

 If you are not educated in the workings of decompression

procedures please seek out training from a reputable
internationally recognized training agency before using this
product.

 Using pure Oxygen or Oxygen enriched gases, Trimix,

Heliox or any gas mixture that contains an Oxygen content more
or less than 21% (straight air) needs special safety measures
and appropriate training. Please consider the general safety
considerations of using breathing mixtures other than air.

 No decompression table, program, schedule or output can

ever assure that you will not be subject to decompression
sickness. Use of this software is at your own risk.

 If the diver uses the wrong value of the gas mixture he /she

or the dive computer could calculate insufficient decompression
time (EAD, END, PO2, PN2) or oxygen toxicity (MOD, CNS, OTU
etc.). Both situations could result in death or serious injury.

 Avoid risky situations which are marked in this manual with

CAUTION and STOP

 Do not use Nautilus Dive Planner for actual dives which

you have not been trained for.

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arnings and Safarnings and Saf

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General InformationGeneral Information

General Information

General InformationGeneral Information

This user’s guide is designed to help the certified diver, nitrox
diver, mixed gas diver, or rebreather diver to: understand the

need and application of planning dives that require
decompression planning. This manual does NOT purport to be a
replacement for certification courses in the subject area or will it
provide information on how to conduct the operations of a
single dive or series of dives. Users who utilize the values
presented in NAUTILUS accept all risks of use.

This user’s guide will provide information as to the operational
use of the NAUTILUS Dive Planner Software program.

The Nautilus Dive Planner Software is for the trained and
certified diver, and gas mixing technician. Nautilus Dive Planner
Software requires that the user analyze and verify BOTH the
oxygen and helium content of any gas that will be used prior to
completing any dive that has been planned with the Nautilus
Dive Planner Software program. A complete log should be
maintained for all gas mixtures. It is the USER’S SOLE
RESPONSIBILITY to properly record the gas percentages and
label the cylinder being analyzed appropriately. Improper gas
analysis and transferring that improper analysis to the Nautilus
Dive Planner Software may produce decompression results that

can cause injury, disability, or death.

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a complete study or presentation on dive
planning, or decompression planning. Users
should seek out other additional information for
those areas of expertise.

WARNING: USING OXYGEN MIXTURES

CONTAINING 16% or LESS OXYGEN

CONTENT AT THE SURFACE CAN CAUSE

INJURY OR DEATH FROM HYPOXIA

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Nautilus Dive PlannerNautilus Dive Planner

Nautilus Dive Planner

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1.1 NAUTILUS DIVE PLANNER OVERVIEW1.1 NAUTILUS DIVE PLANNER OVERVIEW

1.1 NAUTILUS DIVE PLANNER OVERVIEW

1.1 NAUTILUS DIVE PLANNER OVERVIEW1.1 NAUTILUS DIVE PLANNER OVERVIEW

Welcome to NAUTILUS Dive Planner Software.
NAUTILUS is the new generation of Technical Dive
Planning Software and the most comprehensive dive
planning tool developed during the last few years. We are
now 15 years into desktop dive decompression software
products yet most of the products on the market are
limited in their ability to deliver a wide variety of features
and functions. Many have been homegrown products
that have gained cult-like loyalty by some users, but still
lack the full features and variable controls desired by most
of today’s advanced and technical divers.

The introduction of NAUTILUS Dive Planner
Software is a new approach to planning decompression
dives and in the manner in which it delivers the myriad of
information a diver needs to efficiently plan, compare, and
analyze dives. It makes no difference to NAUTILUS if
the diver is using one gas, three gases, or ten gases. It
also makes no difference if the diver will dive on
conventional open circuit scuba or closed circuit scuba, or
a combination of both—NAUTILUS manages it all!

Nautilus Dive PlannerNautilus Dive Planner
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algorithms. NAUTILUS allows the user to make
adjustments to the outputs of those algorithms through the
use of gas selections, avoiding stops at particular depths,
selecting maximum PO2 levels, choosing stop time or run­time, inserting micro-bubble minimization deep stops and
much more!

This Version of NAUTILUS DIVE PLANNER
introduces a wide range of new and exciting features that
were previously unavailable to desktop decompression
planning. With NAUTILUS users are able to make
detailed plans and then perform a simulated dive based on
that information. During the simulation NAUTILUS will
track and inform the user of a wide variety of information
to help you plan and execute an actual dive. NAUTILUS
is not intended or designed for the novice SCUBA diver,
but rather for the experienced diver or a diver who is
enrolled in a qualified training course where NAUTILUS
is being introduced.

NAUTILUS is a control panel for the technical diver or
instructor. The NAUTILUS control panel allows the user
to make rapid selections of important components of the
dive plan in an easy-to-understand manner. By utilizing
“tabs” similar to that on a notebook the user can quickly
navigate to the area they want to work in, make the
selections, save that information and then plan the dive
and create the table output.

NAUTILUS allows the user to select from not one but a
variety of popular and proprietary decompression

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1.2 NAUTILUS USER VERSIONS1.2 NAUTILUS USER VERSIONS

1.2 NAUTILUS USER VERSIONS

1.2 NAUTILUS USER VERSIONS1.2 NAUTILUS USER VERSIONS

Nautilus Dive Planner Software comes in six versions.
Each is a complete full working version of NAUTILUS
but is limited in the maximum operating depth. These
depth levels correspond with popular technical diving
certification levels. We do not limit the purchase of any of
the versions except for one. The licensee of one version
will be able to purchase upgrades to the next depth
version.

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Nautilus Dive Planner Software uses tabs inside the
program to allow for navigation to the individual function
pages. They are arranged left to right in the order that the
user will access them after the initial setup. Ultimately
once the users “standard” preferences are set the tabs will
not need to be accessed until the next time preferences
need to be modified. This section will describe each TAB
set. The next section will take you though each of them
with screen shots.

UTILUTIL

US FUNCTION TUS FUNCTION T

UTIL

US FUNCTION T

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ABSABS

ABS

ABSABS

Nautilus 70 Maximum Depth 70 fsw / 21 msw
Nautilus 140 Maximum Depth 140 fsw / 42 msw
Nautilus 225 Maximum Depth 225 fsw / 68 msw
Nautilus 330 Maximum Depth 330 fsw / 100 msw
Nautilus 660 Maximum Depth 660 fsw / 200 msw
Nautilus RE Maximum Depth 1500 fsw / 455 msw

We anticipate that the most popular versions will be
Nautilus 140, 225, and 330. The Nautilus RE (research)
version is limited in availability to laboratories, universities,
military, and commercial diving companies only.

Each version of Nautilus allows for complete
decompression planning with either open circuit, closed
circuit or a combination of those diving modes. Users can
select from air, oxygen, nitrox, trimix, heliox, nitrox
setpoint or heliox setpoint gas modes. Users can plan
square, multilevel, or repetitive dive profiles with complete
control and interchangeability of diving modes.

Nautilus Dive Planner is the only decompression planning
software that incorporates the full functions of a true
decompression planning tool with a choice of
decompression algorithms and models.

1.31 GENERATE PROFILE:

Here is where the actual dive profile is entered and
viewed in a simple graphical display. Square profile,
multilevel profile, and repetitive dives are easily plotted
here and the decompression profile is viewed.

Preferences:

This is the heart of Nautilus’ settings. Under this tab the
user will select:

Units: Imperial or Metric

Table Type: Stop Time or Run Time method of display

Scuba Type: Open Circuit / Semi-Closed Circuit

SAC rate in cfm or lpm

Closed Circuit (Constant PO2)

High Set Point (either heliox or nitrox)

Low Set Point (either heliox or nitrox)

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Decompression / Bailout SAC rate

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Deco Stops Intervals 10-30 fsw in 1 foot increments

Air Breaks: No Air Breaks

Classic Air Breaks

Custom Air Breaks Rule

Decompression Models:

- Hamilton-Kenyon Model (DCAP) 11 compartment

- Buhlmann 16 compartment

- 4-Compartment Serial (DCIEM)

- 10 Compartment Neo-Haldanian

- 12-Compartment (Huggins-Nafe)

- Variable Permeability Model (VPM)

- US Navy

- Conservatism Slider Bar – 0-90

Deep Stops: No Deep Stops

Pyle Stops

Reset: This resets all changes to the Preference Screen
to the base defaults.

Save: This saves the preferences set for use now and
until it is reset.

1.3.2 GAS SETUP

The GAS SETUP screen is divided into two sections:

Available Breathing / Decompression / Travel
Mixes section with 14 predefined gas mixtures including

air plus the ability to create and save up to 13 more
“custom mixes.”

Define Custom Mixes allows the user to create specific
mixes that can then be added to the Available Mix
portfolio.

A future feature will have the Gas Portfolio linked to the
GAS MIXING tab for automatic entry to aid in creating
the gas mix routine for actually mixing the gas.

Custom Rule Stops

Altitude: Starting Altitude

Post Dive Altitude

Deco Preferences:

Max PO2 on Deco .16 bar/atm - 2.0 bar/atm

Shallowest Deco Stop: 10-40 fsw (3-12 msw)

Avoid Stops at: 10, 20, 30, 40 fsw (3,6,9,12 msw)

Avoid Stop at custom depth

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1.3.3 TABLE OUTPUT

This Tab is where NAUTILUS displays the output of the
Dive Profile and allows the user to View, Print, Export,
and save the display of the dive. Users can choose from:

- Short Table

- Long Table

- Schedule Output with variable time and depth

- Export to Text File

- Export to HTML

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1.3.4 COMPARE

This feature allows the user to compare, separate, and
distinct profiles. This is an outstanding feature for looking
at the time depth profiles, comparing OC to CCR, or for
presentation and educational purposes.

Overlay Mode: - shows the dive profile graph on top of
each other.

Two Window Mode: - shows the dive profile graphs
stacked one above the other.

1.3.5 MANAGE PROFILES

Database listing of dive profiles stored in NAUTILUS
allows the user to scroll through previously created
profiles and to access the data, modify, and re-save if
desired.

1.3.7 GAS MIXING

Complete calculator for mixing gas either from empty or
partially full cylinders.

Mixing modes include:

Nitrox using:

Oxygen and Air

Trimix using:

Helium and Air

Helium, Oxygen, and Air

Helium and Nitrox

Helium, Oxygen, and Nitrox

Heliox and Air

Heliox, Oxygen, and Nitrox

1.3.6 FORMULARY

Formulary is the fun screen that allows the user to access
tools that will help them look at different gas mixes and
identify certain facts about them including END, CNS,
OTU, RMV, PO2, MOD and much more.

Finally a complete decompression planning program that
will run on Windows, Macintosh, or Linux operating
systems. Only Nautilus Dive Planner brings you all the
features and algorithms in one place!

Air Top Ups of:

Nitrox or Trimix with the ability to add a specific gas so
as to change the final composition of the mix.

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2.1 Opening Screen2.1 Opening Screen

2.1 Opening Screen

2.1 Opening Screen2.1 Opening Screen

Screen DescriptionsScreen Descriptions

Screen Descriptions

Screen DescriptionsScreen Descriptions

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OPENING SCREEN

The opening screen of NAUTILUS Dive Planner requires
the user to read and either AGREE or DISAGREE with
the terms and conditions of the use of the program.
Nautilus keeps track of each time the program is
launched.

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When the user clicks the I AGREE, button then the
program will allow full features and functions. Should the
user click I DISAGREE, the program will exit.

2.2 Preferences2.2 Preferences

2.2 Preferences

2.2 Preferences2.2 Preferences

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Units: Imperial or Metric (in sea water)

Table Type: Stop Time or Run Time

Scuba Type: Open or Closed Circuit and the associated

SAC rates for those modes. If Closed Circuit mode is
used, the Setpoint is to be indicated here.

Air Breaks: Nautilus allows the user to have “classic” air
breaks while breathing oxygen. When the decompression
time on with a PO2. of 1.3 exceeds 20 minutes, a 5 minute
break will be inserted, with the next lowest nitrogen based
mixture or trimixture, if nitrox is not available. Nautilus takes
into consideration the time off the oxygen when calculating
the remaining decompression.

Decompression Model: Choose from seven models.
Keep in mind that only one model may be used for a series
of dives. Switching between models during a repetitive dive
series is not permitted. They include:

 

 Hamilton-Kenyon Model (DCAP) 11 compartment

 

 

 Buhlmann 16 compartment

 

 

 4-Compartment Serial

 

 

 10 Compartment Neo-Haldanian

 

 

 12-Compartment (Huggins-Nafe)

 

 

 Variable Permeability Model (VPM)

 

 

 US Navy

 

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Conservatism Slider: increase decompression time over
the base algorithm from 0-90

Deep Stops: Choose from No-Deep Stops, “Pyle
Stops,” or Custom Rule Stops. Pyle Stops inserts a 2
minute stop 1/2 way between the maximum depth of the
dive and the first required stop. Then, 1/2 way again
between that stop and the required stop and then 1/2 way
again until the required stop is reached. NAUTILUS
credits at the shallow stops when it can for these deep
stops.

Altitude: Set the Starting Altitude of the dive in msl
(mean sea level) and set the Post-Dive altitude. Starting
Altitude is where the dive will be conducted from. Post
Dive Altitude is where the diver will ascend to, after the
dive is completed. This can be used where there is a
mountain range the diver must cross after the dive or a
non-pressurized cabin plane.

Deco Prefs:

Max PO2 on deco: Set the maximum PO2

desired for the MOD of the decompression gases to be
used. Note that if 1.6 atm PO2 is desired the slider must
be set at 1.61 atm PO2, otherwise, the gas will not be
enabled at the 1.6 atm level. This applies to other levels
as well. For 1.4 atm PO2 set it at 1.41.

Shallowest Deco Stop: Set the shallowest stop

desired using the slider. Nautilus will calculate the
decompression to that depth.

SAVE: This button will save the preferences set until they
are reset by the user. Upon opening NAUTILUS these
preferences are enabled and table generation can begin.

RESET: Press this button to reset all the preferences to
the standard defaults.

2.2.1 NAUTILUS STANDARD DEFAULTS are:

Imperial (FSW)

Stop Time

Open Circuit SAC .75 cu ft

Classic Air Breaks

16-Compartment Buhlman

15 Conservatism

No Deep Stop

Sea Level

1.61 atm PO2 for Decompression Gas

Shallowest stop at 10 fsw

NAUTILUS assumes instantaneous descent. Meaning
that bottom time is calculated at the maximum depth
immediatley from the time the diver leaves the surface.

Avoid Stops at: This is a great option to help

avoid stops in areas where it may not be feasible to do a
stop due to sea conditions or topographical conditions.
Chose from 4 preset depths or enter a specific depth.

Deco Stop Intervals: Set the interval between

stops. (3, 5, 10, 15 fsw.) Smaller intervals make a
smoother decompression shape.

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Users are to follow the ascent rate indicators of their
bottom timing devices or dive computers. The ascent rate
to the first stop should be at a rate of 60 fsw / min (20
msw/Min.) Thereafter, 30 fsw / min (10msw/min).

2.3 Gas Setup2.3 Gas Setup

2.3 Gas Setup

2.3 Gas Setup2.3 Gas Setup

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NAUTILUS Gas Setup screen is where the user creates
the “Gas Portfolio” that will be available for creating
profiles and tables.

Here the user will select the gases that are expected to be
used for a particular dive or that the user would like to
have available while planning dives.

There are 15 pre-defined gas mixtures that are commonly
used for divers. There are also 14 additional “Custom
Mix” placeholders available for creating additional mixes
for the gas portfolio.

Creating a Custom Mix is as simple as using the sliders to
specify the composition of the gas mixture desired
NAUTILUS will display:

- MOD based on 1.6 atm PO2

- Min Operating Depth assuming a PO2 of .16 atm. - -

- Equivalent Air Depth for nitrox mixes.

- Equivalent Narcotic Depth assuming oxygen is included
in the narcotic properties.

Click: Mix this Gas and it will save it to the gas portfolio.

SAVE: This button will save the gas portfolio selected
and they will now be available for generating profiles.

RESET: Press this button to reset the gases in the
portfolio to Air and Oxygen only.

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2.4 Generate Profile2.4 Generate Profile

2.4 Generate Profile

2.4 Generate Profile2.4 Generate Profile

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Square ProfileSquare Profile

Square Profile

Square ProfileSquare Profile
Illustrated in stop time.Illustrated in stop time.

Illustrated in stop time.

Illustrated in stop time.Illustrated in stop time.

Generate Profile is the area where the user will plan the
dive and generate the first set of decompression numbers.

If this is the first time using NAUTILUS the Preferences
and Gas Set-up need to have been visited before
generating a profile. If, however, the Preferences and Gas
Setup have been completed the user can start off at the
Generate Profile tab.

Examples shown with 18/50 trimixExamples shown with 18/50 trimix

Examples shown with 18/50 trimix

Examples shown with 18/50 trimixExamples shown with 18/50 trimix
EAN 36% deco and 100% oxyygenEAN 36% deco and 100% oxyygen

EAN 36% deco and 100% oxyygen

EAN 36% deco and 100% oxyygenEAN 36% deco and 100% oxyygen

2.4.1 CREATE SINGLE SQUARE PROFILE DIVE

Generating a profile with NAUTILUS is quite simple.
With the Preferences and Gas Set up already in place
enter the DEPTH of the Dive and the TIME for the dive.
Check the pull-down menu and ensure the bottom mix
desired is selected.

Press the DIVE button. This will now enter the first “leg”
of the dive. The decompression “ceiling” will be
displayed to the right of the dive button. This ceiling is
essentially the first stop.

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To perform the decompression calculations using All
Available Gases that have been selected in the GAS SET
UP, confirm that there is a 0 in the “Decompress to a
Depth:” area and press DECO.

NAUTILUS will calculate decompression and perform
gas shifts are the appropriate levels based on the
maximum PO2 selected in the PREFERENCES tab. A
general Depth / Time schedule will appear to the right of
the dive graph.

From here, the user can either SAVE the dive profile by
pressing the SAVE button or press RESET and start all
over again.

2.4.2 CREATE A MULTILEVEL PROFILE DIVE

Creating a Multi Level Profile with NAUTILUS takes just
a little more work but is still quite simple.

1. Decide the levels desired.

2. Enter the First Level in the Depth / Time boxes and
press DIVE

3. Enter the Second Level in the Depth / Time boxes and
press DIVE

4. Enter the Third Level in the Depth / Time boxes and
press DIVE

As many levels as desired may be entered. They can start
out with operational descent stops or they can map out
the contour of a deep wreck or cave site. The possibilities
are endless!

After the final leg of the dive is entered move to the
Decompress section. Look at the Ceiling next to the final
DIVE button. This will be the first stop area.

PRESS the DECO button and the decompression is
calculated.

Muti-level ProfileMuti-level Profile

Muti-level Profile

Muti-level ProfileMuti-level Profile
Illustrated in runtime.Illustrated in runtime.

Illustrated in runtime.

Illustrated in runtime.Illustrated in runtime.

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CREATING PROFILES
USING CLOSED CIRCUIT

To create dive profiles where the diver will be using a
closed circuit rebreather, the user needs to:

1. Enter the Preferences Tab and change the Scuba
Type from Open Circuit to Closed Circuit.

2. Set the High Set Point and Low Set Point for the
rebreather you are using.

NAUTILUS ALPHA VERSION assumes binary diluent

gases for the calculations when using a
CCR. Meaning, if you are using Heliox, it
assumes you will be using only helium and
oxygen and that your unit will adjust the
oxygen accordingly with the balance being

helium. If you are using nitrox, then the unit
will adjust for the oxygen accordingly with the balance
being nitrogen.

Most CCR divers will have the diluent for helium dives set
up as a 17/83 oxygen/ helium mixture and will have
oxygen on board. For nitrox dives they will have air 21/
79 oxygen/nitrogen as the diluent and will have oxygen on
board as well.

NAUTILUS does not presently calculate CCR
decompression using trimixture diluents.

ENTER THE CCR PROFILE

Select the Generate Profile tab. Enter the Depth and
Time and select the Setpoint gas in the pull-down to the
right of the minutes box then press DIVE.

After the dive has completed the first leg the user can
decide on how the decompression will be completed by
selecting the appropriate decompression gases and /or a
setpoint.

If the decompression will be with all CCR then the user
need only select that set point gas and press DECO. The
decompression will now be completed.

If an off-board decompression gas will be used, tell
NAUTILUS to decompress to the desired depth or the
MOD of the off-board decompression gas using the CCR
set point, then select the off-board decompression gas for
completion of the decompression. (eg: decompress to
habitat depth, then complete decompression with OC
gas.)

3. SAC for the “Deco / Bail Out” should off-board OC
gasses be desired.

4. Continue to set the other preferences.

5. Press SAVE -- the preferences are now saved.

Next enter the Gas Setup Tab

Under the Gas Setup Tab, the CCR user can deselect all
gas mixtures OR can select a bailout gas or off-board
decompression gasses. When gases are either selected or
deselected press SAVE and the gas portfolio will be
saved.

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NAUTILUS will then calculate the decompression
accordingly with the gas shift. If air breaks were selected,
then it will calculate those as well.

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Square ProfileSquare Profile

Square Profile

Square ProfileSquare Profile
CCR Heliox High-SetpointCCR Heliox High-Setpoint

CCR Heliox High-Setpoint

CCR Heliox High-SetpointCCR Heliox High-Setpoint
Classic Deep StopsClassic Deep Stops

Classic Deep Stops

Classic Deep StopsClassic Deep Stops
Gas Shift to Offboard OxygenGas Shift to Offboard Oxygen

Gas Shift to Offboard Oxygen

Gas Shift to Offboard OxygenGas Shift to Offboard Oxygen
Classic Air Breaks (on CCR)Classic Air Breaks (on CCR)

Classic Air Breaks (on CCR)

Classic Air Breaks (on CCR)Classic Air Breaks (on CCR)
Illustrated in stop time.Illustrated in stop time.

Illustrated in stop time.

Illustrated in stop time.Illustrated in stop time.

NAUTILUS will allow the use of multiple off-board
decompression gases and allow the user to create “what
if” scenarios, illustrating bail outs with off-board gases as
well. The user needs to set up a gas portfolio under the
GAS SETUP tab to have access to those gases.

Another feature of NAUTILUS is its ability to allow the
user to conduct repetitive dives (next section) moving
from CCR to OC seamlessley. It is not uncommon for
the dive professional to conduct one dive using CCR and
then complete another dive with OC scuba. NAUTILUS
will help the user create these special schedules. All the
user needs to do is to create the gas portfolio for BOTH
dives in the initial setup.

Creating multi level dives with CCR is no different than
when they are created with OC modes of diving. Simply
select each level desired and press the DIVE button until
the dive is completed then press DECO with the desired
decompression Setpoint or off board gases as discussed
earlier.

In the classic book 20,000 Leagues Under
the Sea. Captain Nemo’s “Nautilus”

submarine had a library that held more
than 12,000 books.

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2.4.4 REPETITIVE DIVES

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NAUTILUS creates repetitive dives with relative ease.
After the user has set up Preferences and Gas Setup,
return to the Generate Profile tab.

Create the first dive as described earlier indicating depth
and time and the bottom gas to be used. Then, complete
the decompression. After the decompression is complete,
enter the SURFACE interval in Hours and Minutes. For
purposes of this illustration, select AIR as the surface
interval gas.

After the Surface Interval is entered, press the
SURFACE INTERVAL button and the surface interval
will be created.

Next, enter the new dive with the new gas mixes (if
changed) and complete the dive as normal. If a third dive
is desired or a series of dives is desired, repeat the
repetitive dive process.

Note: NAUTILUS will allow for Surface intervals using
gases other than AIR, but must only be done with proper
supervision and support.

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2.5 Manage Profiles2.5 Manage Profiles

2.5 Manage Profiles

2.5 Manage Profiles2.5 Manage Profiles

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NAUTILUS has a dive filing system that allows the user
to SAVE each and every dive profile for future use. Each
profile saved includes the actual profile, gas selections,
and preferences.

To save a profile press the SAVE button on the
Generate Profile tab. If a specific file name is desired,
enter it, otherwise NAUTILUS will assign a “Dive-XX”
number to the saved data.

To load a dive, enter the Manage Profile tab, select a
particular dive, and press LOAD. The dive will be loaded
back into the Generate Profile tab where it can be viewed
or modified.

To delete a dive, enter the Manage Profile tab, select a
particular dive and press DELETE. The dive will be
deleted from the NAUTILUS database.

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2.6 Compare2.6 Compare

2.6 Compare

2.6 Compare2.6 Compare

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NAUTILUS features a unique COMPARE function
screen that allows the user to select two dive profiles and
compare them in two graphical forms.

Overlay: In this mode, NAUTILUS will overlay two dive
profiles. This view is helpful in visualizing the effects of
time and depth of two dives on the decompression of
each. This is helpful in identifying operational problems
with a particular dive profile.

Two-Window: In this mode, NAUTILUS will place the
dive profiles in two seperate windows on the screen. This
mode allows a more general comparison of disimilar dive
profiles. It is helpful in analyzing multi-level dives and in
comparing dives using either Open Circuit of Closed
Circuit equipment.

To access the dives, use the pull-down Menu and press
DISPLAY for each dive desired. NAUTILUS works
best with two dives. More windows will be available in
future versions of NAUTILUS.

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2.7 T2.7 T

2.7 T

2.7 T2.7 T

NAUTILUS allows the user to output the generated dive
profile in a variety of formats These formats are generaly
refered to as Tables or Schedules.

A Table is defined as a Schedule for a Single dive.
NAUTILUS allows for a variety of table “formats.” In the
Alpha Version there are four Table Formats available.

Classic - This format follows that of the traditional US
Navy type tables.

Enhanced - This format will show a single depth dive
and bottom time with one or two time intervals. A
Detailed table will show, The Model Name, Table Title
(saved name) Bottom Mix, Decompression mixes, gas
shift depths, decompression times, oxygen partial
pressures, and oxygen limits achieved in both CNS %
and OTU, as well as any operational instructions.

able Outputable Output

able Output

able Outputable Output

Condensed - This format will show a single depth with a
series of bottom times in 3 or 5 minute intervals.

Speed - This format is a compact format for printing on
small cards and laminating to be carried by the diver.
Users are strongly urged to print Amplified tables to
review all the pertinent data about the dive before using
Speed Tables.

The series of schedules can be generated with EITHER
the deepest portion of the dive or the longest portion of
the dive. This is helpful for multi level dives where bail­out schedules are desired.

The user can also generate “what-if” tables to take into
account lost decompression gases.

NAUTILUS outputs to HTML files now which can be
viewed in the standard web browser and printed in
whatever mode is prefered.

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2.8 F2.8 F

2.8 F

2.8 F2.8 F

2.9 Gas Mixing2.9 Gas Mixing

2.9 Gas Mixing

2.9 Gas Mixing2.9 Gas Mixing

2.10 Help2.10 Help

2.10 Help

2.10 Help2.10 Help

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completed at this time.

completed at this time.completed at this time.

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Nautilus Dive PlannerNautilus Dive Planner

Nautilus Dive Planner

Nautilus Dive PlannerNautilus Dive Planner

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3.1 NAUTILUS DIVE PLANNER DECOMPRESSON3.1 NAUTILUS DIVE PLANNER DECOMPRESSON

3.1 NAUTILUS DIVE PLANNER DECOMPRESSON

3.1 NAUTILUS DIVE PLANNER DECOMPRESSON3.1 NAUTILUS DIVE PLANNER DECOMPRESSON
MODELSMODELS

MODELS

MODELSMODELS

The Nautilus Dive Planner provides an interface into the
following decompression algorithms:

Parallel models:

Hamilton-Kenyon 11 Compartment Parallel (TII-11F6)

Decompression ModelsDecompression Models

Decompression Models

Decompression ModelsDecompression Models

computers that are made in Europe. (Interestingly, these
machines only track eight (8) compartments, therefore a
NAUTILUS derived repetitive dive profile will be more
conservative than a dive computer using what is billed to be
the “Buhlmann” model!) Buhlmann models track helium
loading and allow for the tracking of helium + nitrogen
loading in the theoretical compartments. These methods
were first used in manned dives in the early and mid 1960’s.

Buhlmann 16 Compartment Parallel (ZHL-16a)

Hamilton-Kenyon Bubble Model

Buhlman Bubble Model (VPM-X)

US Navy 1965 (12-Compartment Parallel)

3.2 Parallel Model Overview

These models simultaneously load all of the theoretical
compartments with inert gas at an exponential rate based
upon each compartment’s half-time. All models use a value
for each compartment that determines its supersaturation
gradient. The Buhlmann model uses two factors (“a” and
“b”) and the other models use a value called “M”. The
compartment that has the “deepest” minimum tolerable
ambient pressure is said to be the “controlling” compartment,
based upon the compartments inert gas load factored against
its allowable amount of supersaturation (“a” and “b”, or
“M”). Theoretically, as long as the diver does not ascend
above the minimum allowable depth, no clinically observable
decompression illness symptoms are likely to be observed.

The Buhlmann models are “folded” into many popular dive

The 10 Compartment Parallel, 12-Compartment model and
US Navy model are based on the calculation methods
derived by the Haldane’s dating back to the early 1900’s.
The 10 Compartment model is used in many US made dive
computers and the 12 Compartment model was used in the
Orca Edge Dive computer. In 1989, Nafe was able to
extend Huggins 12-Compartment model to track using the
same computational method that Buhlmann had been using
for the previous 25+ years. Nautilus allows the tracking of
helium in the diver’s breathing mixture using this
computational method, which is similar to using “equivalent
air depth” for employing an air table while breathing nitrox.

No diving profile or decompressionNo diving profile or decompression

No diving profile or decompression

No diving profile or decompressionNo diving profile or decompression
model including those generatedmodel including those generated

model including those generated

model including those generatedmodel including those generated
from within NAUTILUS can assurefrom within NAUTILUS can assure

from within NAUTILUS can assure

from within NAUTILUS can assurefrom within NAUTILUS can assure
me that I will not be injured orme that I will not be injured or

me that I will not be injured or

me that I will not be injured orme that I will not be injured or
killed.killed.

killed.

killed.killed.

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3.3 Hamilton-Kenyon Model

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11 Compartment Parallel (TIIa-11F6) (aka DCAP)

NAUTILUS Dive Planner is the only commercialy available
decompression software product to liscense the Hamilton­Kenyon decompression model for use in generating
decompression schedules for the technical diver.

The “model” has been incorporated into some proprietary
rebreather decompession computers, most notably the Cis
Lunar and others to be available shortly. Some of Dr.
Hamilton’s algorithms for oxygen handling have been used
in many of the popular dive computers. Until now the only
way to get “tables” using the Hamilton-Kenyon Model was
to have access to the famed Key West Consortium Tables
which were the basis for most of the trimix diving done during
the 1990s, or to have tables provided by NOAA during the
USS Monitor projects (NOAA Trimix 18/50 is based on
Hamtilon-Kenyon Model) or to have a set of tables created
on a custom basis by Hamilton Research Ltd. Dr. Hamilton
has created highly reliable tables using the TII-11F6 model
for such notable dive operations as: Key West Consortium,
Casadore Project, Pillar Project, WKPP, Andrea Doria
Expeditions, USS Monitor Expeditions and many others.

NAUTILUS is fortunate to have been able to liscense the
Hamilton-Kenyon Model for the NAUTILUS Dive Planner
Software. The relationship between R.W. Bill Hamilton and
NAUTILUS co-author Joel Silverstein goes back more than
a decade. The two have worked on many projects together
including authoring two texts on oxygen enriched air diving
for NAUI and for the YMCA. They were co-authors of the
NOAA Diving Manual sections on Nitrox and Mixed Gas
Diving and were the principal and co-investigators for the
Decompression Survey of Air and Air with Oxygen diving
for the US Navy Biomedical Research division. Mr.
Silverstein has relied on the Hamilton-Kenyon Model for
his personal diving and that of his pojects since 1991.

The Hamilton-Kenyon Model has been referred to over
the years as the DCAP model. DCAP is not a model it is a
computer analysis program that allows Dr. Hamilton to create

and model decompression profiles that extend far beyond
the uses and needs of the technical diver.

The computational program identified as the Hamilton­Kenyon algorithm uses, in our internal terminology, the
Tonawanda IIa model using Matrix MF11F6 computed with
Hamilton Research’s DCAP. It uses a Neo-Haldanian
computational algorithm designated Haldane-Workman­Schreiner. It uses 11 halftime compartments ranging from 5
to 670 min. The ascent-limiting matrix was developed to
permit deep air dives using air decompression without
compromising established decompressions from short,
shallow air dives. The development was empirical, based
heavily on experience, but formal statistics were not used to
design the matrix. Although designed originally for air the
algorithm has proven to be highly reliable for dives using
oxygen-nitrogen-helium trimixes.

DCAP dates back to commercial diving in the 1960’s when
the search for offshore oil found commercial diving
companies doing heliox diving; up to that time only Navy
tables were available, and they did not meet all needs for
offshore diving. Dr. Heinz Schreiner led a development
team at Ocean Systems, Inc., in both computation and
laboratory validation of new heliox tables. This was done in
collaboration with others, some of whom were then the
leaders in decompression, including Bob Workman, Chris
Lambertsen, Val Hempleman, and Albert Bühlmann.
Schreiner’s computational methods were based on
Haldane’s concepts, and they relied heavily on feedback
from the field and other empirical information.

Following corporate changes at Ocean Systems, Inc. the
task was picked up by Dave Kenyon and Dr. Bill Hamilton
and they offered decompression services to others in the
field . From this, in about 1975 the need for a number of
different tables by a European client led to the idea for
Hamilton Research, Ltd., to provide a program to generate
decompression tables instead of just providing the tables
themselves. That is, to sell the goose instead of just the

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eggs. The idea was to design a program that could be used
by engineers and diving supervisors as well as researchers
and would not need a programmer as such. This concept
was accepted, and DCAP was developed and acquired
by several major diving research laboratories. A project to
develop deep air tables by one of the DCAP users, the
Swedish Navy, led to a highly reliable matrix that later was
found to work well for trimix diving also. DCAP is the
accronym for Decompression Computational Analysis
Program.

Description of the DCAP program.

Thus DCAP itself is more a tool for generating and analyzing
tables and profiles than it is a specific model. The User
enters a page of instructions, a Basecase file, into a PC
running DCAP. This describes the dive or dives to be done
and gas mixes, profiles, detailed instructions to the diver,
etc. The Basecase also references other files which define
other variables such as units, the computational model, a
matrix of ascent limits or M-values, the format for the
table or tables, and names other output files to be generated
such as graphics or gas loadings; a notebook file can keep
a record of what has been done. These files use diving and
not computer terminology, normally English, but can be
translated into other languages by the user.

A number of models or algorithms are used by
decompression developers, and they are still evolving; some
are better than others. All of them that work rely heavily on
empirical experience. Hamilton-Kenyon’s experience is
greatest with the neo-Haldanian Haldane-Workman­Schreiner model designated Tonawanda IIa. incorporated
in to NAUTILUS as the Hamilton-Kenyon Model.

difference; these rates are defined by half times for each
compartment (often called tissues but they are not
anatomical), the time it takes for half the difference to be
equilibrated (half the remaining difference takes another half
time, and so on). Gas loadings of inert gases are measured
in partial pressures. The original Haldane method provided
ascent constraints as limiting ratios of partial pressures (the
ratio of current depth to target depth). Because this worked
best only for short, shallow air dives, Workman based ascent
constraints on differential pressures. A matrix of maximum
tolerable gas loadings ( M-values ) for each compartment
at each depth defined the ascent limits; the gas loading
calculated for each compartment is compared with the limit
at each depth, and ascent to the next stop is allowed when
the loadings in all compartments are less than the M-values
(the loadings decay exponentially as ambient pressure is
reduced and gases leave the body). Schreiner made this
work efficiently for different inert gases by using different
half times for each inert gas and summing the loadings in
each compartment. Haldane used 6 half times, others use
more, Hamilton-Kenyon use 11 half times.

Since many decompression computations are done
with Bühlmann’s published method, it is relevant to
compare it with Tonawanda Iia. Bühlmann uses a
similar approach, except that instead of a matrix of M-

values it uses factors a and b for each of the half times;
these tolerated pressures can be converted algebraically
to M-values. In the faster compartments (shorter half times)
the inert gases are summed and compared with a calculated
limit, and in longer compartments the different inert gases
have different a and b values; these are divided proportionally
according to the proportion of each inert gas in the mix.

Haldane’s concept was that different parts of the body (
compartments ), take up gas at different rates, and this is
limited by perfusion, the blood’s ability to carry gas from
the lungs to and from the tissues (rather than by diffusion
around a capillary). Uptake and elimination between lung
and tissue follows exponential mathematics, which means
simply that the rate of transfer is proportional to the

Both methods can vary in their conservatism, but in present
practice the Tonawanda Iia model using the matrix described,
identified as MM11F6, (Hamilton-Kenyon) is a bit more
conservative that the unmodified Bühlmann method. This
combination has worked well with trimix dives. The most
popular use of the MM11F6 matrix has been for the well
known “Key West Consortium Trimix Diving Tables, the

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NOAA Trimix Diving Tables, and the Andrea Doria Off­Shore Diving Tables. These tables have thousands of dives
experience with very good results.. This is the model
included in NAUTILUS.

‘Thus to wrap up, DCAP is a practical result of many years
of collective experience in preparing and evaluating many
types of decompression tables. The DCAP concept does
not limit it to calculations with any specific model there is
currently a choice of several models, and others are under
development. DCAP’s main feature is that it facilitates the
computational and table production process. It can allow
different models, approaches, ascent constraints, and table
configurations to be used. A good set of criteria provides a
practical approach to trimix decompression in the self­contained, open circuit range with a good track record.

While it would be wonderful for DCAP to be an inexpensive
desktop decompression program it just can’t. The powerful
features of DCAP make it far too complicated and involves
far too many variables that need to be handled by a
researcher to make it practical for recreational use. This is
where NAUTILUS comes in. NAUTILUS allows the free
swimming diver the ability to create dive excursion profiles
with reasonable assurance that the numbers work well.
NAUITLUS incorporates the Hamilton-Kenyon Algorithm
derived from Tonawanda Iia.

3.5 Hamilton Kenyon Bubble Model (HKBM

method of calculating allowable compartment
supersaturation is employed.

Application of Yount’s method to Hamilton-Kenyon’s gas
uptake model produces decompression schedules that
have initial decompression stops up to twice as deep as
conventional dissolved gas models and shallow decom­pression stop times that are significantly shorter than
dissolved gas models call for. The use of Hamilton and
Kenyon’s compartment half times avoids the extremely
aggressive shallow decompression stop times that VPM
and RGBM models yield.

This combination of Hamilton, Kenyon, and Yount
produce decompression schedules that algorithmically call
for deep stops, rather than arbitrarily adding them into a
dissolved gas model and having to “pay for it” at the
shallow end of the schedule. The shallow stops are not
arbitrarily shortened based upon the intuition of diver’s in
the field.

The schedules produced by the Hamilton-Kenyon Bubble
Model square with the past 15 years of technical diving
experience that has yielded the following observations:

• Dissolved gas models do not produce initial stops
at great enough depth

• Shallow stops called for by dissolved gas models
are much longer than necessary

The Hamilton-Kenyon Bubble Model (HKBM) is a
melding of Haldane’s method of calculating inert gas
uptake into theoretical compartments. Keller’s method of
summing the partial pressures of multiple inert gas uptake
is employed as well. In the Hamilton-Kenyon Bubble
Model, the half-times for each compartment are taken
from the Hamilton-Kenyon decompression model that has
years of reliable decompression schedule production.

1. Rather than using Workman’s M-value
methodology for determining allowable supersaturation
for the theoretical compartments, Yount’s “tiny-bubble”

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• Deep stops arbitrarily added to dissolved gas
model add an unwarranted shallow decompression
penalty, as do adjustments to the M-values

• Buhlman’s halftimes used with dual-phase bubble
models (VPM) may be slightly too aggressive for field use
(skin-bends are commonly encountered )

Hamilton-Kenyon Bubble Model produces schedules that
include stops and times that describe a more linear, rather
than exponential arc across the depth time matrix, yet still
take into account the empirically derived compartment
halftimes.

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3.6 Variable Permeability Model (VPM)

Dr. David Yount created the Variable Permiablilty Model
that takes into account the suspiscion that sub-clinical
bubbling occurs on every dive of significant depth and/or
time. The VPM-A, VPM-B, VPM-E and RGBM models
were derived from this work initially done by Yount and are
very popular with technical divers today.

The following is an excerpt from Eric Maiken who has
done a significant amount of work with VPM

The Varying Permeability Model (VPM) was developed to
model laboratory observations of bubble formation and
growth in both inanimate (never been alive) and in vivo (soon
dead) systems exposed to pressure. In 1986, this model
was applied by researchers at the University of Hawaii to
calculate Diving Decompression Tables (Reference 1).
Although the original VPM is considered dated by specialists
in hyperbaric medicine, the time lag between the formulation
and public release of the latest decompression methods has
left many divers following ascent schedules that are justified
by obsolete Victorian era physical models. Further
compounding the problem is the widespread use of
commercial decompression software with excessive arbitrary
parameters hiding behind siren-song front-ends that allow
programmers to dish out crucial physiological advice. Finally,
the mathematical and physical bases of the bubble models
have kept them inaccessible to all without degrees in physics
or math and so, apart from reports filtering back from the
front lines, few have understood, seen or used this stuff. So,
caveat emptor —and beware too!

The VPM presumes that microscopic voids, cavities, nuclei
exist in water, and tissues that contain water before the start
of a dive. Any nuclei larger than a specific “critical” size,
which is related to the maximum dive depth (exposure
pressure), will grow upon decompression. The VPM aims
to minimize the total volume of these growing bubbles by
keeping the external pressure large, and the inspired inert
gas partial pressures low during decompression.

It is important to note that the total decompression times
generated by the simplified VPM were FORCED to be
similar to the US NAVY Standard/Exceptional Air deco
times. However, much of the decompression time is deeper
than the USN depths. Presumably, a diver would evolve
fewer bubbles using a VPM schedule than on the Navy
table. This is not very stringent once you consider the risky
(O2 & bends) nature of the old USN exceptional exposure
tables. Yount and Hoffman might better have forced the times
to look like Buhlmann’s for conservatism. The parameters
in the open source code produce Bühlmann-like no-stop
times, and total decompression times between the old USN
tables and the Bühlmann tables.

Why are VPM Decompression Tables so Similar to
the RGBM Tables?

Why have VPM tables always been so similar to Bruce
Wienke’s RGBM tables? Until 2002, this was simply
because the RGBM was essentially the same as the VPM
for a single decompression dive. Even though Wienke claims
to have “abandoned” VPM, his publications and publicity
from vendor partners belive this as marketing over
substance. Wienke apparently still uses core elements of
Yount and Hoffman’s VPM algorithm as a basis for the
RGBM. Even today, in 2004, it can be demonstrated from
commercial programs that the “full-up” RGBM is still
underpinned by Yount and Hoffman’s iterative algorithm.
With the wide distribution of open source VPM, Wienke
was placed under pressure to differentiate his product by
customers who had paid for material that could be obtained
virtually for free. Since 2002, this has resulted in a new
RGBM model, publicized in dive industry print and venues.
Nonetheless, as demonstrated by the close correlation of
ascent data for VPM and RGBM, this work has actually
only resulted in incremental adjustments of the model. You
pay your money and you take your chances.

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Comparison of the VPM to Conventional
Decompression Procedures

A major difference between the VPM and standard
supersaturation algorithms is that the VPM programs use
an iterative procedure to calculate a decompression
schedule. In each step of the iteration, a new decompression
schedule is calculated. The total decompression time is then
fed-back into the calculation to revise the critical gradients
(SUB PNEW in the BASIC Programs), and a more liberal
schedule is produced. Maybe this should be called the
“IGBM” —the increased gradient bubble model ;*) This
process of updating the ascent repeats until the
decompression time converges to what supposedly
corresponds to the formation of the maximal allowable
amount of free gas. The first and last schedules produced
for a short dive are often quite different. This results from
the contribution of both the magnitude of the growth gradient
+G and the time that the gradient acts to drive bubble growth.
After a short dive, the tissues will off gas rapidly to circulation.
Hence, because the time that the gradient acts is small, the
magnitude of G can be increased by allowing shorter and
shallower stops.

VPM tables handle the in and out gassing of dissolved gas
in tissues the same way as conventional neo-Haldane
calculations do. That is, parallel compartments with
exponential half-times ranging from minutes to hours are
used to model the uptake and elimination of inert gas by the
body. This is and off gassing is handled symmetrically in all
of my programs. The divergence of the VPM from
conventional calculations is in the details of how a diver’s
ascent is controlled. Rather than setting limits on the maximum
pressure ratio/difference between gas dissolved in tissues
and ambient pressure (supersaturation), ascents are limited
by controlling the volume of gas that evolves in the body
due to the inevitable formation of bubbles. As long as this
volume is kept smaller than a certain “critical volume,” it is
presumed that a diver’s body has the ability to tolerate the
bubbles. If the volume of bubbles exceeds the critical volume,
the diver is at risk of a pain-hit or worse. The volume of the
gas in bubbles is related to the product: (number of bubbles)
x (Gradient) x (growth time). The number of growing bubbles

is set by the maximum compression encountered on a dive.
This crushing pressure is related to the deepest depth of the
dive as well as the descent rate and gas mixture. All of the
programs on this site directly relate pCrush to the maximum
depth. The gradients and bubble growth time are controlled
by the ascent schedule, with the surface explicitly considered
the last decompression stop.

Rather than using tens or hundreds of arbitrary of
parameters to generate ascent schedules, the main result

of the VPM is the replacement of the ascent-limiting
matrix of M /a-b values with only four constants,
corresponding to measurable physical and physiological
quantities. In the BASIC programs, they are found in
SUB DIVEDATA. The minimum bubble radius excitable
into growth ro = r
gamma = γ , the nuclear crushing tension gc = γ c, and
the maximum tolerable volume of bubbles, which is
proportional to lambda = λ. For the hour-long time
scales treated by this program, the nuclear regeneration
time (see Yount’s eq. 2) is essentially infinite, and hence,
not used. From these constants, critical gradients G are
formed in SUB DIVEDATA on the first iteration and then
in SUB PNEW on subsequent iterations. The critical
gradients limit ascents because they are directly related to
the rate of bubble-growth by the diffusion equation.

Reference: Eric Maiken

http://www.decompression.org/maiken/
VPM_Background.htm

The appendix of: D.E. Yount, D.C. Hoffman, On the Use

of a Bubble Formation Model to Calculate Diving
Tables. Aviation, Space, and Environmental Medicine,

February, 1986.

NAUTILUS incoporates the Variable Permiability Model
into its portfolio of Decompression Models.The user will
have control over the values used for Gamma, Lambda,
and M yielding what NAUTILUS designates as VPM-x

, the skin tension of bubble nuclei

o

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3.6 Future Models and Integration

VERSION 1.0 VERSION 1.0

VERSION 1.0

VERSION 1.0 VERSION 1.0

The goal of NAUTILUS Dive Planner is to be the single
source tool for decompression planning for the advanced
and technical diver. We will continue to seek out and work
with the best minds in decompresison modeling and bring
to NAUTILUS more reliable models as time progresses.

We hope with time to incorporate some of the Navy
Probability models including V-VAL and others.

We also expect to incorporate the ability to import data
from the more popular dive computers and dive data
recorders. This will enable users to “pull” dive profiles into
NAUTILUS and use that data as the basis for creating
repetitive dive schedules. But that is in the future.

THIS MANUAL IS NOTTHIS MANUAL IS NOT

THIS MANUAL IS NOT

THIS MANUAL IS NOTTHIS MANUAL IS NOT
COMPLETE - UPDCOMPLETE - UPD

COMPLETE - UPD

COMPLETE - UPDCOMPLETE - UPD
VERSIONS ARE AVERSIONS ARE A

VERSIONS ARE A

VERSIONS ARE AVERSIONS ARE A
OUR WEBSITE AOUR WEBSITE A

OUR WEBSITE A

OUR WEBSITE AOUR WEBSITE A

http://wwwhttp://www

http://www

http://wwwhttp://www

.nautilusdiv.nautilusdiv

.nautilusdiv

.nautilusdiv.nautilusdiv

AA

TEDTED

A

TED

AA

TEDTED

VV

AILABLE ONAILABLE ON

V

AILABLE ON

VV

AILABLE ONAILABLE ON

TT

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T

:

TT

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eplannereplanner

eplanner

eplannereplanner

.com.com

.com

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VERSION 1.0VERSION 1.0

VERSION 1.0

VERSION 1.0VERSION 1.0

Printed 3/16/05Printed 3/16/05

Printed 3/16/05

Printed 3/16/05Printed 3/16/05

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Tech Diving Limited

a division of Scuba Training and Technology Inc.

2959 Kiowa Blvd North

Lake Havasu City, AZ 86404

928-855-9400

928-855-9529 (fax)

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