Join Date: Feb 2006
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Just a word of caution lest a feeling of false security should set in: You need to seriously downrate electric pumps for any normal installation. You'll find that due to the height between bilge and the top of the vented loop, and the resistance of pipe, bends and any fittings, the fact that your batteries are likely to be at less than the 13.6 volts at which capacity is rated, you will get about 40% of the rated, open flow, capacity. So, your 650 will do 260 gph and your 3500 will do about 1400 gph.
Your manual pumps may be rated at an unrealistic pumping rate - often 70 strokes per minute when 30 strokes per minute is hard work.
A 1.5" hole, 2' below the surface will let in around 60 gallons per minute, 3,600 gph.
Prevention is the best policy.