Furuno CH250, CH250BB, CH270, CH270BB, CH300BBH User Manual

Stabilizing Furuno Sonar

Providing stabilization to sonar gives it the information it needs in order to compensate for your vessel’s pitch and roll,
and keep the transducer pointed where it should be. Unless otherwise requested, all CH37, CH250, CH270 and CH300
sonar’s purchased from FUSA are shipped with the MS100 motion sensor. When mounted correctly, the MS100 works
very nicely for most vessels. However, there are a couple of other stabilization options available, including satellite
compasses or a BS-704 clineometer. Below are some benefits and compromises of each.

Sat Compasses

A sat compass is not always the preferred method of stabilizing sonar. But if the vessel already has a Furuno SC30, SC50
or SC110, it can be used satisfactorily in some cases. The SC30 is preferred over the SC50 or 110 because how the
pitch/roll is calculated, and it is also less susceptible to multipath, which affects accuracy. Even though the numbers on
the multipath index page of the SC-50/110 may be within the acceptable range (under 1.5) the pitch/roll output
accuracy is still affected. Note that the SC60 and SC120 sat compasses do not output pitch and roll.

PROS All of the sat compasses have a zero reference point, which means that when they are powered on, they will
immediately detect the list / orientation of the vessel.

CONS The pitch/roll output of the SC-50/110’s can be affected by multipath.

Note - If you have to choose between the MS-100 and SC-30, choose the SC-30. If you had to choose between a MS-100
or SC-50/110 go with the MS-100.

MS-100

This is the standard motion sensor that is supplied with all smaller sonar. It is very good at sensing vessel movement,
and won’t over swing like BS-704 can on smaller vessels. However it doesn’t have a zero reference point, which means
that it will not immediately detect the list of a vessel if it has been powered off while loading. It is very important for the
MS100 to be mounted correctly. The MS-100 has a top, bottom, forward and aft mark printed on the sides of the case.

PROS Standard supply and fast reacting

CONS No zero reference point

BS-704 inclinometer

When ordering a sonar, the BS704 can be substituted for the MS100 for no additional charge. The size of the BS704 and
the MS100 is similar and they use the same cabling. The BS704 uses two inclinometers to output pitch and roll. The
main difference between the BS704 and the MS100 is that the BS704 has a zero degree reference point. This is very
helpful for fishing vessels that sometimes travel with different trims.

PROS Has a zero reference point

CONS Can over swing the pitch/roll values on smaller faster moving vessels.