alum. pontoon boat for metel shop project

[rhcsavage21]

ok i am kind of knew to the hole boat thing and thought it would be a very hard and interesting project of a alum pontoon boat. it will have duel .81 engines to power two props know the questions i have are 1. what should i put in the tanks a exspandable foam or pressurized air? 2. i was going to use some outdrives that hook in to two different mock out board engines that would be connected to a servo to control the boat is this good or should i change it? 3. this one really bothered me, dose the prop need to have some toype of flow coming twords it so it can push it? 4. dose the engine need a clutch? these are just a few of the question i have. basically what i am trying to do is give it the pontoon boat look but trying to hide everything too. like the out boards would just be a piece of alum that has been shaped to look like one but all it dose is steer. and the fuel tanks would be hidden under seats and the elctronics would be hidden in the console were if it was real boat it would be the ssteering console. but some other things is i am not worried about money. that i can deal with and this boat is going to be big but not big big. well thanks for the help it will be aprsiated. :)

[bufferoo]

If you're going the "big & heavy" way I think some A\B foam would be a great idea. Not the stuff in a can used for insulation though. It requires water to cure and if you're putting it in aluminium it most likely won't cure all the way. I've had this happen before and it's not fun to fix. The stuff that works best is a 2-part mix. You add the A to the B and pour it in before it starts to foam up. You trim off the extra and finish off your work. You may have seen it used in Monster Garage on the Beetle airboat.

I think that if you're going large here (.81 sized) and want an outboard look, maybe if it's in your budget you could go with twin 11cc K&B's. You might be able to get them for a good price off ebay if you're willing to search and wait. No clutches with those though. If you want a clutch you'll have to go inboard and if you're going that large maybe a Z260 would be up your alley.

You "might" even be able to get away with a twin jet-drive setup. One in each pontoon. That would certainly give you the "hidden" away effect you seem to be keen on.

Anyway you setup your engines or drives, yes the props\impellers do have to have water coming towards them. There are some drives in full sized ships (specifically cruise ships) that use a pulling prop rather than a pusher. They're mounted in a pod that rotates 360 around so no matter which way they are steering the prop gets a full bite into the water with no obstructions.

Sounds like a challenging but WAY FUN project.

Good luck.

Bufferoo

[rhcsavage21]

thanks for the help so far i am starting my design using the .81 os engine but i am still desiding on what i am going to do about the drive shaft any more help would be very appreciatted