- #36
Averagesupernova
Science Advisor
Gold Member
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The way I see it is that you can estimate performance based on this: I have used a 10 HP Johnson motor on the back of a small boat and to use something that is only 7.5 HP and guaranteed to be less efficient will probably get you down to a performance that would be similar to sticking a 3 to 4 HP outboard on the back. To stick a trash pump on a boat and expect much is foolhardy. Not to say that it would never move a boat, I am sure it would. We get results in several ways in this world. We go on prior established research of others in the form of specs and etc. which involves some math and other skills that we may or may not have, or we just try stuff.