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[abreese]

since my last posting i have sorted out the charging system on the sub this now seems ok.
on the bench the compressor runs up to 20 psi ,and the suface button sends air to tank ok,but as soon as the boat is put in water the comp does not always respond in fact one dive lost the boat could not fill air tank,not sure how the sensor works on the ballast tank could this be the problem,as soon as i fished out the boat she ran ok on dry land? comp fully reponsive to commands 

[Subculture]

Not an easy one to diagnose on a forum. How is your system set up. Most recirculating type compressed air systems are rigged so that the compressor draws air out of the main ballast tank, storing it under pressure in a reservoir, then to surface you actuate a valve (servo or solenoid) and the air is released back into the tank blowing out the water, and hopefully the boat surfaces.

From your description, it sounds like your boat has this in reverse.

[abreese]

it is the system you describe probably the way i worded my question,as soon as i put the boat in water the comp does not respond as it does dry how does the sensor work in the ballast tank maybe this is at fault?

[Subculture]

Don't know what system you have fitted. SOme use float switches, some use metal probes with an amplifier.

[abreese]

yes this has a small metal probe carried to tank in a plastic tube

[Subculture]

There are different systems out there, some are DIY some are commercial. It could be an electronics issue, or it could be something as basic as a loose connection. Could even be a radio range issue. It's a process of deduction and testing I'm afraid, we can offer suggestions of what may be at fault, but without having the boat in front of you, suggestion is as far as we can go.

[abreese]

many thanks at least getting some idea how it works,just tried it dry in the shed works ok,will check wiring from sensor also see if there are signal issues,let you know how it goes.
cheers AB.

[abreese]

done a bit of poking around checked connections etc the sensor is a conrad unit a commercial part modified ? any way cleaned the probe wire just done six full dives a little trim needed fingers crossed seems ok.

[Subculture]

I've heard of Conrad- the German Maplins. However, I'm not familiar with that unit. Some water detectors feed the probe with a DC voltage, which tends to result in the probe plating up over time, and becoming non conductive. This may be the case with the electronics you have.

Mike Stothers made a dive manager unit which fed the probes with an alternating or pulsed voltage which prevented that from happening. They're out of production now, but Mike may have a few left if you fancy retrofitting one. They're very reliable and rugged units, and were purposely designed for recirculating compressed air systems like yours.

http://microgyros.com/dive_manager.html

[abreese]

thanks will have a look at that,tried again today would seem the trick is to keep the probe clean as you say it may tend to coat.
cheers alan b

[Subculture]

What I don't understand is how it resulting in you losing your boat on the bottom. Did the compressor ingest water? Generally if the probe coats up, it will fail to stop the compressor when the maximum water level is reached. However if you stop the compressor before that point is reached it shouldn't be an issue to surface the boat, as all you need to do is reales the air back into the tank via a valave. If you have a leak somewhere this could affect things.

Might be wroth checking all your pipe work, and putting a pressure gauge inline with the compressor and reservoir to check to see if you have a leak somewhere.

[abreese]

cant find any leaks,she is still working ok,of to a lake this week best go while my confidence is still in one piece will post a result .
thanks ab