Greetings:

I recently read some USENET posts concerning scuba navigation boards.
One stated the rather than buying one, it was easy to make one using a
Ritchie compass. Surfing the 'net, I see that Ritchie compasses are
traditionally used on board boats. So I'm curious how well they stand
up being submersed. To what depth can they be used in a scuba
application? Is there a particular model number that is recommened for
scuba use?

I also notice that some models are listed as having a low-light/night
viewing capability. How are they illuminated? By using a light and
battery source (in which case I doubt they are submersibile), or is it
some sort of chemical illuminiation (like tritium on watch dials)....

Your assistance is appreciated!

http://www.aquanaut.com.au/Prod/Suunto/compasses.html

Marine compasses are liquid filled, so the pressure of depth is not a
problem. Make sure that the mounting hardware is either stainless or
bronze. The lighting for marine compasses consists of a small red colored
bulb connected to the vessel's instrument lighting circuit. The problem is
that this light and wiring is not waterproof. You would have to replace it
if you want illumination. Some compasses might have markings that are
designed to glow in the dark, but I am not sure that this is at all common.
If you jerry rig a waterproof lighting circuit make sure that you keep the
bulb size as small as possible and use twisted wire to connect the bulb. A
small bulb will draw less current: twisting the wire helps cancel out the
magnetic field caused by the current.

Hope this helps,
Dale Bennett

"Quiet Voice" wrote in message
om...
Greetings:

I recently read some USENET posts concerning scuba navigation boards.
One stated the rather than buying one, it was easy to make one using a
Ritchie compass. Surfing the 'net, I see that Ritchie compasses are
traditionally used on board boats. So I'm curious how well they stand
up being submersed. To what depth can they be used in a scuba
application? Is there a particular model number that is recommened for
scuba use?

I also notice that some models are listed as having a low-light/night
viewing capability. How are they illuminated? By using a light and
battery source (in which case I doubt they are submersibile), or is it
some sort of chemical illuminiation (like tritium on watch dials)....

Your assistance is appreciated!