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Old 30 March 2013, 14:53   #1
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Country: UK - Wales
Town: Swansea
Boat name: Space Hopper
Make: RibTec
Length: 5m +
Engine: Evinrude E-Tec 75
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what size prop mercury 75 2 stroke

I am trying to find the correct prop for my merc 75 two stroke, the guy I bought it from put on the wrong one, its currently got h14 x 13p on it, I think it needs more pitch, top speed s about 30 knotts.

wanted to put on a nice stainless one, can someone helpme out?
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Old 30 March 2013, 15:33   #2
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there are propeller charts at merc/mar dealers but they will need to know what revs you are doing at wide open throttle and the weight of the boat including people and equipment an estimate for the weight will be ok,But remember the only accurate test is the water test. welcome to the black art of propellers.
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Old 30 March 2013, 16:38   #3
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Country: UK - England
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Length: 5m +
Engine: Outbaord mariner 75
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Ok my 1991 Mariner 75hp 2 Stroke has a 17inch pitch prop on .
5500rpm at wot.
pushing a old ribtec 5.35
does about 40 Knotts
hope this helps
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Old 30 March 2013, 21:29   #4
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Country: UK - England
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You cant really say which prop is right for you as its sort of personal choice. Firstly you need to find out what revs you are pulling at wide open throttle you need the engine to be at about 5200-5400 rpm. I guess with a 13" you will be over that rev range? Then once you know the RPM you can work out the pitch, each inch of pitch will gain or loose about 200-300 rpm so you should be able to get it about right from there.
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