What will the differential do whilst charging down the river

Hello Fellow Buckaneers,

I've come to beg for help.
I'm planning to build a small powerboat from scratch and need to regularly compare my thoughts and ramblings to real world fysics and expertise.
The thing I'd like to build is slightly based on the mighty v8 powered, flatbottomed, v-driven hotboat. You know, some 18ft long, only protruding a few inches obove the waterline and burdened with horsepower.
Since I live in Belgium, Europe where we tend to think smaller, and since I'm also an aircooled vw nut, I'd like to shrink those headboats a little bit and install an aircooled flat four into it.

Since I kind of know what the boat should look like, I'd like to start of with the engine and drive, and design the hull around this later on.

I know some, if not a lot, of you are opposed against installing a car engine into a boat, and sometimes I can even understand why. So I'd like to point out that this boat would only be used for fun on small rivers and canals, making short blasts into plane and then stop, turn and blast again. Fooling around a bit.

VW engines are easy and quite cheap to rebuild, and you can get performance parts as easy as stock parts. They are aircooled so no need to marinate the cooling system, and a lot of spark avoiding goodies are available of the shelf for the buggy people who enter the woods. Torque is already quite good given the small engine, and can still be enhanced.

Where I'm a bit lost at the moment is the transmission. I'd like to stick to a V-drive but a marine gearbox is so damn' expensive and second hand v-drives are quite uncomon over here. Also I would like to stick to my vw-theme. So I was thinking of using the stock gearbox, either manual or semi-automatic, rebuild this so I'm only left with stern and astern. Then I could put those industrial thingies on that change the shaft direction, I'd bolt them on instead of the outputshaft either side of the gearbox in a 10° angle. This way I'd have some sort of twin prop v-drive. Only what will the differantial do whilst charging down the river.

Have you guys got any thoughts on this other than I shouldn't use the car engine, if so I'd love to hear them.

Thanks for reading this short novella,
Tim Wolff

 

my mistake

I've reposted this thread in design/powerboats/diy marinisation, since it seemed to be more at it's place over there.

Sorry, won't happen again.

Tim Wolff