I have a '78 Sabb 10 hp with a variable pitch prop. I’m thinking of
changing the present blades that are the long tapered style for the
shorter, fatter blades. While the shorter ones have a slightly less
surface area, their shortness will give the prop a larger clearance
in the deadwood cutout which now sometimes gives a "whop whop"ing
sound because of too little distance from the prop end to the top of
the cutout.
I’m wondering if anyone else with this engine on their BCC is using
the smaller blades and if so, are they satisfied with the performance
of the system.
Propeller clearance: between the propeller blade?tip and the hull,??should be at least 15% of the diameter of the propeller, Ie. 20" propeller should have a tip clearance of 3".
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We changed from a Saylor propeller which has narrow thin blades, less drag under sail, less control under power, to a Dyna-Prop, which has shorter thicker blades, better control under power and slightly more drag under sail.
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Personal preference varies, being diesel engine mechanics and sailors, we tend to favor close quarter docking control over a slight reducton in boat speed under sail.
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Best wishes,
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Marty Chin
Bay Marine Diesel