Willydiver,
That looks great - good job!. With the handles so far forward, you better have a good prop shroud, otherwise you might change your name to just "diver"
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Andrew, thanks for the nice words and suggestions. This project definitely was a challenge! The toughest part is utilizing (making them work) the components that I was able to obtain. As you mentioned, finding a suitable motor was the most difficult part.
I settled on the trolling motor because it is already designed for marine use and was cheap ($20, used at a local boat shop). There are some disadvantages to it, though. I don't particularly like the power cord having to be exposed like that. I couldn't get around this because there is no way to run it through the interior of the motor casing. There is a rotating rotor in there. It's ugly, I know. The cable glands in the motor mast and the battery cannister are potential leak points.
The original shaft seal is composed of two rotating shaft oil seals stacked together. No doubt, with some machining, a shaft seal that utilizes a compression spring would be more secure, but I opted to try the stock set up. I did replace the seals, as well as the main body orings to help out. I have heard a range of statements on the depth ratings of "off the shelf" trolling motors. Some people say they've had them down to 100' with no problems. The manufacturers will only commit to 10'. I'll have to gradually test it to see. I'm fairly confident in the water tightness of the battery cannister.
Suprisingly, I wasn't able to find a small, inexpensive DC motor to use from the interior of the battery casing. It would be fairly easy to machine a bulkhead utilizing compression shaft seals. If I could ever find a source for a cheap motor with a stainless steel shaft. Of course, heat dissapation comes into play with interior motors. The overall looks would be alot cleaner versus an exterior trolling motor.
I'm impressed by the Gavins, Farallons, Dive Rites, etc. but they all have one "non-DIY" characteristic in common. They all seem to use the same manufactered motor/handle/prop component (I think from Oceanic?). The sleek looking cannisters look great all the way to the business end, and then you see the same old motor system. I know, this system is "tried and true", but I'm not into just buying the main part of the project and bolting it onto a battery cannister. Got to be a way to build these from scratch.
The toggle switch mechanism is probably the highest potential fail point in the whole project. On the next go-around I'll probably utilize a magnetic reed switch or a camera housing control like Ikelite produces (suggested by mddolson). I'll give this design a try and am sure I'll be back at the work bench trying new ideas.
This project is definitely a first shot at a DIY DPV. I know there is alot of interest in them from this group, so any and all suggestions are great. This one is not really meant to be used for deep cave penetrations or deep technical diving, just to play around with in relatively shallow water. More of a concept trial than anything.
Definitely would save money on haircuts if used without a shroud! I'll continue to post pics as I get the shroud on and other finishing touches.
Thanks again for the input!
WD