About Martin Seymour Expertise My experiance is mainly in Ic powered model boats scale and semi scale. size from 2ft to 7ft long using glow plug and petrol engines.
But NOT multi boats.
I have converted many chainsaw and strimmer engines for this purpose.
also designed and built three sizes of model waterjets for model boats.
Experience
Past/Present clients Many members of the public ---- hobbies.
Question Hi Martin, I am building a 4' rc lobster boat model with a zenoah g26pum marine gas engine. I would like it watercooled with wet exhaust exiting underwater. Any ideas on the best way to do this and parts required ? Thanks
Answer underwater exhaust Question: Hi Martin, I am building a 4' rc lobster boat model with a zenoah g26pum marine gas engine. I would like it watercooled with wet exhaust exiting underwater. Any ideas on the best way to do this and parts required ? Thanks
Hi Richard
Sound interesting, but if it’s a marine Zenoah it will already be water-cooled?
So you will only need to sot the exhaust pipe. Did it come with any pipe work at tall or just the bare engine?
The ideal pipe would be light ally of about ½ “ diameter, but as this martial is difficult to work I would sujest mild steel pipe of the same dia. the pipe can run along the same path as the full size craft may be incorporating a silencer. Before it exits the hull you will have to incorporate an inverted U section so that the top of the U is well above the expected water line then the final section running through the bottom of the hull, with it angled to the stern.
Water can be fed into the system a few inch from the engine connection and lower than the same. The water comes from the cylinder head on the hot side via short lengths of silicon tube. Short lights of brass tube of a suitable dia will need to be brasses into the main exhaust pipe, feeding the hot water into the main exhaust pipe.
Water will then cool the whole system.
It might be a good idea to bridge the inverted U with a short length of water pipe so that it can escape past the inverted U and not cause a backpressure.
If pipes are not available at you diy store you might consider using copper pipes of 15 mm dia as used in domestic plumbing but silver soldering the joints would be better than soft soldering.
Martin
