ok so here is what i have some up with for a frame/hull/chassis/whatever you want to call it in google sketchup. I am not sire i like how it looks. Its a little boxy for me. I may add some foam which i can shape into some attractive curves and help streamline the thing a bit. In terms of scale, This thing is probably about 6-8 ft long and the diver kneels and sits on top in a relatively upright position. The back if flat, because there is going to be a motor shaft sticking out with a prop.
Let me know what you guys think...
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By the way, what could i use for a prop? I am planning to use a 36 or 48 volt 1000 watt brushed electric scooter motor that spins at 3000 rpm. I was thinking a 15-17 inch rc airplane prop (maybe 2 stacked on top of each other) but it would sure be nice to use a marine propellor...
I might still go with 2 trolling motors. Haven't decided yet...
First, yes that looks really boxy to me. If you make more small panels on the front fairing they're a lot easier to smooth into curves, though a plywood panel of the right thickness can easily be bent to make simple curves. Complex curves (two or more bends in different directions) are more difficult but still possible.
You can easily fair in the seams to make it a little more "aerodynamic" if you want to but I still don't understand why you want it to be so long if you anticipate the diver sitting upright. If the diver is laying on it, I could see the need for length, but upright you could easily chop about 3 feet off of that. Then again, if you did that you'd probably want to make the front fairing taller to help flow water around the diver instead of pushing water directly into the diver's chest. Consider motorcycle fairings, which are designed low profile for airflow over a "bent over" rider, or full-size for the "upright" rider. The design you've come up with looks like it's made for someone to lay down on, not sit up-right.
Something I may have missed in all of this is what your thoughts are behind this. What are you hoping to accomplish with this project? Do you just want to get from point to point quickly or do you want to just cruise against currents? Something else entirely?
Most of the scooters I've seen are designed as minimally as possible for several reasons, as far as I can tell. First, the smaller they are the less power they require, typically. That means less battery (and associated cost/weight etc.) It also means they are more easily taken from place to place and stored for the boat ride to the dive site. Second, more complex is more of an intrusion to the dive experience, rather than an enhancement. On a vehicle like yours, how do I stop and keep it neutral? How do I see the things I want to look at while scootering or while trying to hover? With existing scooter designs, it's fairly easy (from what I can tell-I have no scooter experience) to turn the motor off, get myself neutral and let the scooter "float" nearby without dealing with lots of logistics. If I want to be close to the bottom there is more hassle to keep it from dragging but a slightly positive scooter can easily solve that issue. Something the size you're designing takes a whole lot more logistics to keep in place without worrying it's going to bash the user in the head in a current (assuming user dismounts for some reason) or do damage to the environment, either hitting coral or causing a silt-out. Finally, what are the logistics of getting it in the water and actually mounting/using it? As indicated, the smaller scooters are trivially easy to understand with respect to getting them in and out of the water. Probably a little less trivial, in practice, but certainly not hard to figure out. The size you're designing would likely take several people to get in and out of the water unless you have a [jet] ski-lift or trailer.
