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Old 05-17-2015, 02:06 PM   #60
ranger42c's Avatar
City: Maryland
Country: USA
Vessel Model: 42' Sportfish
Join Date: Aug 2013
Posts: 3,777
Originally Posted by Britannia View Post
Here's the easiest way to think of it. Let's suppose the pump needs to pump one pint of water. Let's suppose that the narrow hose holds one pint of water in 4 feet. Then the pump needs to move the column of water up 4 feet. Now suppose that a larger hose is used - with twice the diameter and hence four times the cross-sectional area. Now the pump only needs to move the wider column of water up 1 foot to pump the same pint of water. So it moved 4 times as much water up 1/4 of the distance. So the same work was done by the pump in both cases - and it is not affected by the diameter of the hose (ignoring friction).

But if the pump is here, the thru-hull is there, and the distance is X feet... the pump still has to move the water X feet, yes?

South River, Chesapeake Bay
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