My brand new Westerbeke gen clanged from day one (May, 05). It was rebuilt over the winter and reinstalled with a valve on the water intake, which must be opened to use the generator and closed for running.
Sooooo, on a nice 100+ degree day I run out to my favorite anchoring spot, climb into my nice warm engine compartment and open the valve, asking everyone to remind me to close it before we leave.
There's ten bucks in it for you if you can think of an easier way to do this.

Cigarette puts cables on a lot of the valves so you have easier access. Maybe you can rig up something to close the valve from the cockpit?

How about an electric solenoid rigged to close when the engine starts...this way when you shut the engine off the valve opens and you don't have to worry about opening the valve to go start the gen.....

only issue may be the size of the line your gen set needs for cooling....i did a quick scan in McMaster-Carr and they have a nice Delrin Solenoid Valve that works off 12vDC but the biggest pipe size is 3/8"....

here ya go found this one searching through google.....get it normally open untill energised and hook it up to the ign circut of the engine.....when the engines not running the valve is open and you can run the gen...then when you start the engine up the valve closes and shut off the water supply...now that i think of it....try calling Porter Pipe they are local to Chicago here and the guys a boater and part of the Chicago Powerboat Club...i'm sure they could help ya find what ya need...

http://www.jeffersonvalves.com/valvesmodels/1314.asp

Why does the valve have to be closed when your running ? To much pressure ?

probably would flood the gen from the water pressure...gaskets may not be strong enough to hold the psi out....

Why not hang the pickup off the transom where at high speed the pickup would be out of the water.Also if i was going for the electric valve i would definitely opt for the valve being closed when not energized.

Why not hook the electric valve to the generator 115volts that way when it starts the valve opens, when you turn the gen off the valve shuts.

CM

well i would agree with that if there was no on/off valve there in the first place....but since there is a valve there i would just add it on right after the valve and the only reason i would go with a normally open valve is if the solenoid ever fails you wont be out of a working generator....you would just go back to opening and closing the valve manually like he's doing now.....but i do agree with ya that a normally closed valve would be best in most circumstances....