torro

Just would like to enquire as to how a water cooling system is set up on an RC Gas boat. Any pictures or help would be much appreciated. I was thinking of just machining the engine block of my Husqvarna back, wrapping a suitable diameter copper or brass pipe around it put a barb on each end and run some rubber tube to an out-take pipe that'd shoot the hot water into the air, or i could have it under hull to expell the water there. And for water intake, underneath the hull, fibreglass in a shallow but wide scoop sufficient enough for water to be passed easily into the rubber hose and circulate around the tubing on the engine block. I see some people use pumps for their waterjackets, but i rekon with this continuous spiral of pipe the forward motion of the boat would be enough to force water through. Keeping the intake small would minimize drag.

w3bby

Hi torro,
Check out this thread [link=http://www.rcuniverse.com/forum/m_3312007/tm.htm]watercooling[/link]. Although this is a zenoah you are wanting to do the same thing.
Water intake can be from the rudder or from an inlet under the boat. You don't need huge scoops, a 4mm i/d tube should be enough mounted at a shallow angle and sanded flush. You can buy fittings for this, here's an ex. [link=http://www.czarnecki.pl/fsr/photo/products/new/new_v49.jpg]inlet[/link]
If you reverse this idea you have an outlet that will draw water through and can be used as a self bailer (but do a loop of tubing over the waterline!).
The only difficulty I can see with a tube spiral is getting enough contact surface to ensure good cooling.

vsop

Waterpumps are mostly used for boats that have a clutch.. So that when at idle the engine does not overheat. Once they start moving the pump goes into bypass and the water pressure from the pickup is plenty.

If you wish to do spiral wrap around the head you will want to consider soldering the pipe to the head or some other method of thermal transfer.

torro

Thanks for the help guys, much appreciated. Yeah i also was worried about the surface area to allow thermal conductivity. I would have like to have bought a water-jacket already made up but i doubt i could find any hop ups for a Huskie (Husqvarna) engine, and my lack of metal working tools i have in my posession i.e. a hacksaw and file, not that it would be impossible to do with those tools, just very hard so i opted for an easier alternative. And yeah solder should work well to transmit the heat, and of course i'd use some plumbers solder that comes in real thick stick, could even go for some silver solder.