Through-Hulls

kwaltersmi · #1 (**permalink**) 08-29-2007

My current project boat (Helms 25) only has one through-hull. The through-hull is plumbed to two separate drains in the cockpit. My plan is to add a through-hull or two for a couple of bilge pumps I plan to install. Frankly, I'm surprised that the boat didn't come from the factory with a through-hull for a bilge pump.

My question is: How do I determine the proper location in the bilge to mount the pumps? I would assume that at least one should be in or very near the lowest part of the bilge. My initial thought is that the back-up bilge pump should be mount a bit higher in the bilge.

sailingdog · #2 (**permalink**) 08-29-2007

I wouldn't put the through-hull for the bilge pumps below the water line. That makes it very difficult for the pump to evacuate the water... since it has to fight the pressure of the water on the output lines... Generally, the output for the bilge pumps is above the waterline.

I would mount a small "maintenance" bilge pump down in the bilge as low as possible, with a relatively small capacity and a relatively small diameter hose. This minimizes the return water that comes down the hose when the pump shuts off. Then mount a larger, high-capacity pump about the same level, but with its switch a bit higher than the one for the small maintenance pump. That way, this larger pump will empty the bilge if the small pump gets overwhelmed, but will stay off otherwise.

kwaltersmi · #3 (**permalink**) 08-29-2007

Good stuff SD (or should I call you Don Casey?). Most of what you recommend is mirrored by Don Casey in his books.

The bilge pump installation is my biggest concern at the moment. My boat has a swing keel and I fear that it's going to have a slow leak (or worse, a fast leak!). The boat will be moored and I'll be away from it for at least a week at a time. I guess I'll know more after I splash the boat next spring and keep a close eye on it for a week or two before leaving it. My biggest fear is the pumps and batteries not being able to keep up with a leak while I'm NOT on the boat. Perhaps I'll need a solar panel for reasurrance.

sailingdog · #4 (**permalink**) 08-29-2007

Get a solar panel to help keep the batteries topped off...and install a bilge pump counter... and log the readings when you are about to leave the boat.