mikef
regular
Reged: 16/05/2001
Posts: 8939
Loc: chesham, bucks and palma,major...
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Why the difference between 2 sets of props?
15/05/2008 08:35
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Spot the difference between these
and these
Nope, I can't see any difference either and they're supposed to be exactly the same pitch/dia except that the second set make my boat go 2.5kts faster than the first set
The manufacturer quotes a top speed of 28kts for my boat with the engines that are fitted but, until now, my boat has only managed 25kts and revved to 150rpm short of the rated max engine rpm. Over the 3 years I've owned the boat, I've tried everything to find those missing kts. I've had the engines and throttle linkages checked, props polished, removed weight from the boat by leaving the bimini and tender on the dock and run with near empty tanks but all to little avail. Ferretti kindly supply a spare set of props with the boat which are stored in the lazarette. I've had them examined by a yard and have been told that they're exactly the same as the set fitted to the shafts. This year when the boat was lifted, I thought what the hell, I might as well swap them over and, hey presto, the engines now run to their rated max rpm and the boat does 27kts which, given the extra equipment and cruising gear on my boat, is acceptably close to the manufacturer's own figures
So, why the difference? The props are supposedly the same pitch/dia and are in equally good condition. Does the performance of props degrade over the years?
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