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Which prop to use
I have a new Yam 70 4stroke on an Osprey Viper 5.2m rib.
The max Rev range in the book is 5300-6300rpm
With a 15 prop it revs to 5800rpm and 26kn.
My preferred cruising speed is 19 kn which is 4600rpm
With 13 prop I get 26kn at 6200rpm and 19kn at 5000rpm.
My main concern is fuel economy. The Rib is used for fishing so no towing anything or warp factor speeds.
My thinking is because the 15 is reving slower at my prefered cruising speed then this is the better prop for fuel economy.
Or is it???? Any thoughts would be most welcombe.
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