Tuesday, October 27, 2015

The Slurpee Bilge Pump

The ideal bilge is both clean and dry, but this is tough on an LNVT.  Water, either via the packing gland, Bomar hatches, or the anchor hawse constantly finds its way into the bilge.  Current bilge pump technology removes most but leaves about 1/2" of standing water.  Described below is a solution that can be easily made at home.  
Here's the setup for the Slurpee dry bilge: 
  • 3.3 gpm diaphragm pump
  • 1/4" plastic tube
  • 1-1/4" x 3-1/2" x 6" soapstone strum box
  • Scotchbrite pad.  In operation the Scotchbrite pad, which acts as a filter, is face down. 

The soapstone has 3/8" holes drilled in it as follows:

This system is effective because the diaphragm pump's vacuum is strong enough to entrain any water in or below the Scotchbrite pad.  I tested the 3.3 gpm pump to a height of 5' with no decrease in the 1oz/sec flow rate.   Allow the pump to run for few minutes after the area around the Scotchbrite is dry and there's no backflow.  A manual switch can activate the pump.  Included with the switch is a programmable 12V relay (~$10 from Amazon).  This way the pump can be automatically run on a fixed schedule.  Set and forget--I hope. 

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