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Sunday, September 11, 2011

Aft Bilge Pumps Dryfit

A dry bilge is a happy bilge. On the Westsail 42, the lowest point in the bilge is in the far aft near the shaft log. The floor of the bilge slopes downward to this point, where there is a small sump. There are some challenges for placing a pump here. This sump is quite narrow, maybe 3 to 5 inches wide. Large enough only for a medium size all-in-one centrifugal pump. Also, the sump is deep in the boat making service access quite a reach from the floor level. As with the forward bilge pumps, I decided to install a "crash pump", for use when you really have some water ingress to the boat. And a "dry pump" to help keep the bilge as dry as possible.

Aft bilge pump bits.

The pump choices are:
  • Whale SuperSub 1100 (24v) - is the dry pump and is 100% submersible. It is long and narrow and fits nicely in the sump. It has a "duckbill" like pickup strainer that sits in the lowest low point of the bilge to pickup most of the bilge water. 
  • ITT/Jabsco Heavy Duty Diaphragm Pump (24v) - is the crash pump. It can pump ten gallons per minute. It will be mounted higher in the boat, inside a cabinet somewhere, with a hose reaching down into the bilge connected to a strainer for pickup of bilge water.
To make installation and future service easy, I fashioned a small bracket assembly (from Coosa board) designed to be dropped into the bilge sump. Fastened to this assembly is the Whale SuperSub pump underneath, the pickup strainer and the float switch for the Jabsco pump are fastened on the top. It will be installed and removed as one unit. The "dry pump" will act as "first line of defense" to keep things dry. If it can't keep up, the "crash pump" kicks in once water level reaches a certain height.

Assembled bracket with pump bits mounted.

Assembly lowered into the bilge sump. A nice snug fit.
Next, plumbing the discharge hose, wiring the electrical, performing a dry (wet?) test.

1 comment:

The Incredible Hull said...

Good move with the "aqualarm" bilge switch and panel. I am about to change out my rule float switch which I have absolutely no faith in.