I think everybady has this question ,how to choose the bilge pump ?this is ideas about boat pump from HYDRULE ,the manufacturer of bilge pumps .
Unfortunately, there are no pat answers because the criteria for an adequate pumping system depends on the style of the boat, not merely its size. Some types of boats are more vulnerable than others, like sport fishermen and open boats. In any case, for every type there is a basic minimum. The table below lists what I think that minimum is based on boat length.
Boat lengh No. pumps Total Capacity (GPH)
16-20 2 2500
21-26 2 3000-3500
27-35 3 3500-4500
36-42 3 6000
43-49 3-4 8000
50-59 4-5 9000-10,000
60-60 4-5 10,000+
There are two factors which must be considered, the capacity of pumps and the number of pumps. The number of pumps is important from the stand point that bilge pumps are not reliable because they are electrical devices submerged in water. Contrary to common belief, the pumps themselves rarely fail; its the electrical system from which they operate that is usually the cause of the failure. Because of this, one way to improve reliability is with redundancy, or increasing the number of pumps to decrease the odds of complete loss of pumping ability.