Model Forum / Radio Controlled / Water Models / September 2004

depends on what kind of motor your using. Electrics commonly use pickup
tubes  facing forward and water is pushed into them with the motion of the
boat. Gas or Nitro can use a vacuum diaphragm pump that runs off the
crankcase changing pressure to pump the water. These pumps are commonly used
on 2 cycle marine and snowmobile engines to pump the fuel into the
carburetor.

Only engines equiped with a clutch need a pump to pump cooling water.  In
low rpm, the boat will not move, so require pumping cooling water.

For those boats do not equiped with a clutch, the boat will move as long as
the engine is running, water pickup continue to work.  The boat will stop
only if the engine is off.

I think the high temperature in the pipe header is highly risky, especially
in those boats with a closed motor compartment.  High temperature in the
pipe will damage the nearby substance, the r/c box and/or flotation.

Most bent pipe header do not come with cooling ring so require hand made
cooling ring.  The cooling ring material is low cost aluminium tube, easily
obtained from hardware store.  Sealing was cut from silicone tube, the tube
used to join the pipe to the pipe header.