Cooling problem.

[Andres vW]

My father and I have read the site and gotten much helpful information during our search for a 31 Bertram. In late 2010 we became the owners of a 1978 Flybridge Bertram 31, completely redone in 2007. This is our first post on this site.
Our problem is that the builder put both the freezer pump and the a/c pump on the same strainer/thruhull, and we are unable to run both equipments at the same time, as the intake, 1", feeds both pumps, each a 3/4" . Each time we try to run both equipments, we get air locks, which makes the pump with the air lock overheat and shut down. we have meanwhile also burnt out 3 pumps that way, until we finally have given up using the freezer until we can find a solution to this. Any ideas?
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[In Memory of Vicroy]

Two ideas, first one is easy, add a second thru hull. second one is to use flexible impeller pumps - they won't air lock, but do make a good bit of noise. If it were me I'd add a second thru hull and be done with it...first I'd contact whoever put both on one thru hull (or have your lawyer contact him) and suggest it would be appropriate for him to put a second one in free.

UV

[mike ohlstein]

Or.....if you don't want to make a second hole in the boat, make the one you have bigger and add check valves to each intake hose just after the Y.

[CaptPatrick]

I'm just old school...

Dedicate one through hull fitting to one application. Period.

The only exception I ever make is with the livewell pump that I use, which as a 90 degree 3/4" take off just before the pump in order to supply water to a separate wash down pump.

I would never rob water from a critical piece of equipment to supply anything else. If "too many holes in the bottom of my boat" is an issue, build an over kill water chest that's more than capable of supplying water to everything via one really big through hull.

But that even is putting all of your eggs in one basket. What happens if that single hole gets stopped up? Multiple malfunctions simultaneous is what. Then there's the issue of space...

As to check valves, be careful. Spring loaded check valves are notorious for failure and are, in some cases, outlawed by the Coast Guard. Gravity/flapper style check valves are OK, but only if constructed of marine grade materials and are installed above the waterline, which is self defeating since a check valve works best just after the water source.

[Bruce]

Centrifugal pumps won't open a check valve.

99.99999% chance on ac and a freezer that's what they are and burn out easily because of lack of water which cools and lubricates the magnetic drive in the pump.

Either a sea chest type of system with enough fre flow to handle both pumps or individual inlets.

Also even though a pump has a 3/4 inlet, use 1" minimum full flo thru hull and ball valve. If you look at standard ball valves the inlet diameter shrinks going thru the ball.
Better to go to 1- 1/4. I try and put a t on the thru hull the stem of the t gets plumbed to the pump. The wing of the t goes on the thru hull and the other gets a pipe plug. This way you can remove the plug and clean out the thru hull.

BTW these types of pumps need a scoop for speed. If you don't they can easily lose prime.

[Andres vW]

Thanks for the options guys. It seems an additional thru hull will be the best solution. I'll check if I have somewhere "accessible" to put one in.
Andres.

[In Memory of Vicroy]

Put it as far aft as you can. The B31 hull rises striaght up on its lifting strakes and will put those thru hulls up forward out of the water in rough seas. I burned up a couplre of a/c pumps that way before going to a huge Jabsco flexible impeller pump that will suck the chrome off a trailer ball. The scoop is another solution.

UV

[Andres vW]

Thanks for the tip, I will haul out sometime next month and will see what works best.
Andres.