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[Patrick Henry]

Just wondering if I should install a water pump in my cruiser to keep water circulating through the system when I'm just pottering along?

At high speeds the water pickup should allow plenty of water through, but if I'm running at slow speeds for a while, then am I going to get enough water through it to keep the motors cool?

I have a 12volt screenwash pump I could use(the boat has a 12volt system)but I have an idea that these aren't happy if running continuously...is that correct, does anyone know?


Ta,



Rich

[pompebled]

Hi Rich,

If you use a small scoop on the inlet, positioned where the propwash hits the bottom of the boat and make the outlet face towards the transom, creating suction, while keeping the tubes and piping as low in the hull as possible, you could do without a pump.

If you run a few yards at speed, the system will be filled with water and the flow will remain, even when you potter around slowly.

If you've chosen the motor(s) accordingly, the motor(s) will not heat up substantially when you potter around, only when you open the throttle, the motor(s) will have to work and need some cooling, specially if the fast runs are longer than a few minutes.

What size and weight is the boat and what motor(s) did you use? (I'm guessing the Sea Star?)

Let me know if I have to elaborate more and add pictures.

Regards, Jan.

[Patrick Henry]

Hi Jan,

Yes, you're quite correct...it is the Sea Star.

The motors are 2 x ACTion 550's driving a pair of 35mm five blade Raboesch brass props, the water outlet is off to the right side, above the water level, and just under the rear step to allow swimmers access back onboard. Battery pack is a 12volt 3700a/h cell pack, an ACTion esc(without BEC)and a separate 6volt 1000a/h battery pack to run the lights and sound effects.

I'll only be going at speed every now and again, most of the time the boat will be running at around half power at a guess.

She's just over a metre long, as for all up weight...haven't a clue yet, there's still a bit more to install.


Rich

[pompebled]

Hi Rich,

For the system to work without a pump, the outlet must be in the bottom, a pipe slanted towards the transom, creating suction.

Here's a crude sketch:

The intake  (inlaat) doesn't have to extend into the propstream, just a small scoop and positioned where the propwash hits the bottom.
The outlet (uitlaat) can be in the last part of the bottom, just make sure it's out of the propwash.

Regards, Jan.

[ACTion]

Rich
You won't need water-cooling with those motors on that set-up. They will happily take 18v in other circumstances (and they're 555 i.e. 5-pole motors, not 550 3-pole). Try running without cooling to start with - "KISS".
DM