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Old 14-02-2016, 14:28   #31
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Re: folding prop yes or no

If properly selected, a fixed prop is the most efficient there is for motoring, if you gain over your fixed, you had the wrong prop. Many props like the Maxprop for example are inefficient due to their blade design, you will always lose a little with a Maxprop in motoring, but of course most don't but a folding or feathering prop for motoring do they?
The exception to that rule is an Autoprop, due to its blade shape, you ought not lose any efficiency over a fixed, but the Autoprop really comes into its own Motorsailing. In calm seas with 6 kts of wind on a close reach, I can Motorsail at 6 to 6.5 kts with my motor at 1000 RPM. I sail at 3 kts. Much rolling of course in those light winds, and I can't keep the sails filled and just motor with the main up.
An Autoprop is sort of a poor mans variable pitch prop, which would likely be the ideal, assuming the operator knows enough to use it correctly.


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Old 14-02-2016, 14:49   #32
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Re: folding prop yes or no

Quote:
Originally Posted by rabbi View Post
+1

Since no prop will live up to that expectation I'd suggest to keep expenses low.
That means I would get whatever folding or feathering I can find for as little money as possible.

Here is a test (in German only). Takes into account resistance, maximum maneuvering power fwd and rev, top speed, RPMs, etc
The cheapest model costs 1/2 to 1/3 of the others and came out quite well, except on reverse.
That Radice/Allpa didn't make it into the Yachting Monthly tests (and one does wonder just why ) yet is made by one of the biggest prop makers around.

At the list price for mine plus* VAT (580), I'm really tempted to fit one to try when the boat is out for its CopperCoat (the existing will be a handy spare then, and if it needs it I can send it off for a service as well).

Best reduction in drag with a long keel, is to fit a 2 blade so it can feather itself behind the keel, out of the flow.

PS Hey a64, thanks for that very good discussion you and others had about 5/16" anchor chain recently. Thanks to that I now have a clear plan for my ground tackle setup (I was ripping my hair out a bit as to what was optimum).

*Priced the wrong one with VAT so fixed it. Doh!
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Old 14-02-2016, 15:10   #33
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Re: folding prop yes or no

With a full keel Tashiba you aren't going to get any significant speed advantage even if you took the prop off and sailed without it, the ultimate folding prop. The benefit of a folding/feathering prop are virtually nil because of all that keel that's in front of your current prop. May be other benefits than speed but I wouldn't pay the freight to get it. If you had a fin keel boat with the prop hanging down naked, might be worth the investment.

FWIW, Cruised W32 with a fixed 2 blade that we tucked vertical between the deadwood for sailing so it had almost no drag. Also delivered two W32's with fixed three blade props. Had the best days run with the 3 blade prop though it was only by a couple of nm, 181nm vice 178nm.
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Old 14-02-2016, 15:45   #34
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Re: folding prop yes or no

Has anyone worn out a 3 blade Gori beyond repair?
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