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Re: [PSUBS-MAILIST] Tired of Going in Circles



Hi Dan,

I've used the Precision Navigation TCM2 electronic compass in Remotely Operated Subs. It worked reasonably well and could be calibrated for iron in the vehicle. These go for $600 to $700 if I recall correctly. They have a 0-5V output that could be wired to an inexpensive LCD. You'd still need a laptop or palm pilot to calibrate it though.

Given the amount of iron in your sub you want the compass sensor mounted outside the hull in a non-ferrous pressure vessel. The simplest would be a short piece of 2" PCV pipe.

A simple first step would be to mount a dive compass someplace visible from your viewport, though it may not work at all because of the iron hull. A dive compass should cost under $50

The ideal solution would be to find an electronic car compass that has a hard wired remote sensor. That way all the engineering is done and it's price lower since it's mass produced. It may actually be possible to open a PNI wayfinder and split it's sensor module from the rest of the compass. They also sell just the sensor modules so it's possible one could be reverse engineered.

It would be worth trying the electronic compass inside the sub, just because if it works it would be a huge hassle saving. I probably wouldn't expect it to work though.


The sensors are here:

http://www.pnicorp.com/group?nodeId=c30


mike


On Oct 20, 2004, at 6:47 PM, Dan H. wrote:

Hello All,
 
Well, I've had My K-350 "Persistence" out several times this summer, and now that the local waters are clearing up more as they get cooler, I'll be getting in several more dives until it freezes.  As of yet, I haven't done a deep water test but dived manned to fifty feet several times and had no problems.  I don't care to take it any deeper then that until I do an unmanned deep water test to five or six hundred feet.
 
I've had a bunch of fun with it, even though I haven't seen anything spectacular.  With the practice, I'm getting better at controlling it.  It still bobs some as I'm submerging, but I now keep that down to no more then four degrees fore and aft.  Running a straight line when going top speed (don't ask me how fast but it's faster then one could row) is still difficult.  The faster I go the easier it is to get in a quick unintentional turn.  I know a tail fin would help but I don't think I want to add one yet.  
  
The other thing that I need to do is install some sort of directional device.  I'm thinking a gyro compass.  Once I loose sight through the conning tower viewports, I'm traveling blind.  Even near the surface, unless the sun is shining through the top view port, I can't get oriented and keep it there.
  
Does anyone know where I can get a gyro compass or anything else to tell direction with, other then a new gyro for an airplane out of the catalogue at $1600 a pop?  Also, most airplane gyros seem to be vacuum powered.  I need either 12, 24 or 36 volt powered. 
  
How do you other guys tell direction ?  Keep in mind I've been diving in pea soup where vis is no better then four feet.  To give you an idea how many pees are in the soup around here, at forty feet, there is ZERO light coming from the surface.  With the lights off, IT'S DARK!!!!
  
Thanks for any help, Dan H.





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