External water pick up question
 

I have a Cigarette Bullet that has Hardin Marine adjustable external water pickups for engine cooling. The boat is freshly restored and only has a couple of hours on it. I have mechanical water pressure gauges and I have the pickups for the gauges before the sea pump. My plan was to use the gauges to tune the water pickups until I got them where I wanted then move the gauges to the block for normal water pressure. I am a little to surprised to find the pressure before the sea pump is negative at speed. I lowered the water pickups 1/8” on 2 occasions so 1/4” total with no change in pressure. I expected to see some pressure in that line after I lowered the pickups. The water temp is where it should be so apparently it’s getting good water flow. Right now the pickups are about 1/4” below the bottom of the boat. Should I be seeing some pressure before the sea pump at speed or is the sea pump going to pull so much water that just won’t happen? Thanks for the help.

Pressure measure restriction, so it sounds like your sea pumps are just flowing so much that there is nothing to create pressure. My pickups are even with the bottom at the leading edge and maybe 1/8 lower at the trailing edge

I have exactly the same situation in my fresh build, but thru the bravo dual water pick up. Have seen all the threads about too high water pressure, very confused 🤔.

Bernoulli effect.
Pressure drops as fluids speed up.

The amt of Water psi in the block is what you are concerned about. No ? I don’t get the psi gauge in frt of the pump but my bulb is barely lit.

I would have thought that the pickups could supply more water at speed than the sea pumps could handle and create some pressure on the intake side but it looks like that is not the case. I will move the gauges to the block and see what the readings are there. Thanks for the help.

I tought so too, now i feel stupid 🤣

That can depend on speed. If a boat is going 120mph at 5000rpms, a lot more water will get forced through the pickup than a boat going 60mph at 5000rpms. What really matters is the psi in the engine.