Charlie
My Auto prop came from AB Marine Do they still sell Autoprop and if so would you be able to check the price for an H5 now. Any fixed blade prop will create more drag than a folding or feathering prop. Most of us dont like drag on our sailboats, I think a large percentage of sailors want to go faster under sail and that means a folding or feathering prop on our secondary means of propulsion, the engine. I noticed that when I replaced a 2 blade Martec folding prop with a fixed two blade for the new owner when I sold the boat that not only did she lose speed (more than ½ kt under some conditions) but the fixed 2 blade prop also created an annoying noise when under sail, sort of destroyed the tranquility sometimes but I could always tell it was there, the boat just felt and sounded a lot different dragging it along. He wanted the prop changed because he was a beginning sailor and he wanted more control under engine power (while docking especially) and I had the right fixed 2 blade prop for the system which might have been from factory build so he made the Martec his spare. _____ From: CnC-List [mailto:[email protected]] On Behalf Of [email protected] Sent: January 14, 2014 5:53 PM To: [email protected] Subject: Re: Stus-List folding prop for C&C 40 I strongly support what Bill and Andy said about a possible different prop. One other important consideration for a two bladed prop is the amount of space between the prop tip and the hull. Most 2 bladed props will be larger in diameter than a 3 blade to make up for the lack of surface area in the blades for equivalent thrust. Depending on the prop rpm and pitch, there needs to be a certain minimum space or the prop may produce cavitation or otherwise interfere with the hull. As you will soon find out, from this list or a vendor, a prop change is hardly as straightforward as pulling the old and installing a different one. When I re-propped my 36 (from 3 blade Maxprop to 2 blade folding Gori), I had to replace the transmission to get the reduction needed for good overall efficiency between the motor rpm, the tranny reduction and the prop pitch. When these are matched, it should be possible to achieve your theoretical hull-speed at or near your engine maximum RPM, at least in flat water and with an engine which is appropriate for your displacement. I found Goeff at AB Marine (a Kiwi) to be an excellent source of information on all of the above. Charlie Nelson Water Phantom C&C 36 XL/kcb
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