<font color='#000080'>I knew someone else would think of this one too. I've got plans on one.
We reckon at the moment that a god way to go might be to have a piece of tubing with a prop in the centre. This way, we only have to seal the battery and motor, and we don't have a big leaky compartment in the middle. My bset bet so far is a piece of that big yellow tubing the gas people use. Plastic, reasonably hard, and looks capable.
Someone did mention that it can give off funny gases when it gets wet. I presume they're talking tat, but does anyone have further info on that?
Another option is to buy the plans for a serious bit of kit. There's a website with some major ideas on it, that I think could take me the best part of a few months, and a much bigger garage than I have! They look more like a submarine than a DPV, but certainly have got enough to get me thinking. I could dive all of Stoney in one go, and stay dry!!!
It'll be just like SeaQuest. Without the dolphins, maybe.
OK, all I've got is a picture with "Markham Sport Submarine" made by Kent Markham. If anyone can find a website, you've got more spare time than I do. And I'm a student.
They sell plans on everything from a diddy one-man to a two-man semi-closed sub.
Apparently, the yellow tubing they use for gas isn't suitable for use underwater - it isn't tough enough for those kind of pressures (queried it when I was considering making a torch cannister out of the stuff)
Diggs, the gas I believe is hydrogen. The reason for keeping the motor and batteries separate is that there is a theoretical chance that hydrogen given off during battery charging could be ignited by sparks from the motor/switches.
I don't think soucing materials for the body is going to be that hard. I think the hardest bit will be a) the switching and b) the motor. Switching could be difficult if anything other than a simple on/off - a standard reed/relay + magnet combination is fairly standard. The hard part would be varying the power, without losing it. The motor that Gavins etc use is an electric trolling motor, designed to power small craft and designed to go under water. The only problem is where the hell do you get them in the UK, and also that they are very pricey.
If any electrical geniuses out there can suggest a suitable motor alternative, I'd be very interested!
I don't like the idea of buying plans. I'd like to see them first, and since most of them are US-based, sourcing parts might be tricky.
The Gavins are made from an Oceanic Mako scooter. I think you can buy the motors as that is what GI does and also Silent Submersion. All you then have to do is put a body and nose cone together (if only it were that simple!!)
PVC Tubing is used in gavins and is very strong. HDPE is also used on the nose cones and stuff. If you use HDPE you may have to use strengtheners of some sort
<font color='#000080'>I wasn't going to use it for a cannister. The gas tubing was going to be like a fan, with water channeled in one end and out the other. It's not withstanding any pressure etc.
I've got a mate getting me a knackered propellor fairly soon, then all I need is something to drive it. I get the feeling that's the difficult bit. What about the motor from an electric lawnmower? They go at a fair RPM, and should drag most things through the water with the right prop. There's probably a load of them down at the scrappers, or you could ask around.
An idea I had for a switch was similar to my mate's torch, it's got 4 settings from full to off. You just press it again and it goes faster. Must be able to get a waterproof one of those.
Don't you like the design WL? I like the hands-free concept. I also like the way it makes best use of what's already on the diver e.g. the cylinders. Great link, by the way.
As for buying the motors, that's the problem. They use American trolling motors which are a) over in America and b) bloody expensive!
Digger, you mean like the Bog-o-zep here? Bog-o-zep
Also, using other types of motors is what I'm after, but using something non-specific means extra headaches of a) how do you seal the motor in and b) how do you waterproof the bearing so it can turn the prop without letting water in?