What do I need to try gas?

[Kez]

Hi All,

I want to give gas boat a try but do not want to spend a whole lot nor do I need racing performance for my first attempt. I am scratching a 50" crusier (sorta like the Prather fun crusier). The plan is to buy an inexpensive weed whacker and stripe the engine. Can you tell me what else I will need to make it suitable for R/C boating use? I am totally ignorant on gas engine.

1. Flywheel?

2. Cable nut or universal joint? What size thread is a typical gas engine crank?

3. Is water cooled head necessary?

4. If I want to use hard shaft, would 1/4" SS be suitable?

5. What size prop (fully submerged) can a unmodified gas engine turn?

Thanks,

Kez

 

[Mike G]

Go with a homelite if you can find one, they are the cheapest and easiest. Use the flex shaft that comes with the trimmer, 1/4 with square end. They can handle about 10,000 rpm without being water cooled as long as they have plenty of fresh air to cool them. Solid shafts are very hard to line up correctly, the vibrations will kill your radio equipment if not properly done. Fully submerged prop, a guess would be a Prather 270 (yuck) Octura X670 or X470, 2 or 3 blade.

When you take it off the trimmer do NOT cut too much of the shroud off the engine, the flywheel sucks air in and pushes it out over the cooling fins, if you cut too much back you will lose cooling effeciency. The outside air going over the fins is not enough, you need the forced air from the flywheel, or water cool it.

Have fun!