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Thread: Folding Prop Performance Question

  1. #1
    Moderator Christian Williams's Avatar
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    Folding Prop Performance Question

    It is acknowledged that most of the benefit of a folding or feathering prop is at low hull speeds, where drag is most critical.

    In the real world, how about higher speeds?

    Do folks with Martec and similar brands perceive a notable difference near hull speed?

    When it's blowing 20 knots, does a folding prop matter?

    (I ask because I tend to turn the engine on if boat speed languishes, and sailing at two knots is rarely done for long. That sort of cruising and day sailing also obviates any real need for an a-sym or huge genoa. I currently drag a large three-bladed prop.)
    Last edited by Christian Williams; 06-12-2019 at 09:07 AM.
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  2. #2
    Quote Originally Posted by Christian Williams View Post
    It is acknowledged that most of the benefit of a folding prop is at low hull speeds, where drag is most critical.

    In the real world, how about higher speeds?

    Do folks with Martec and similar brands perceive a notable difference near hull speed?

    When it's blowing 20 knots, does a folding prop matter?

    (I ask because I tend to turn the engine on if boat speed languishes, and sailing at two knots is rarely done for long. That sort of cruising and day sailing also obviates any real need for an a-sym or huge genoa. I currently drag a large three-bladed prop.)
    I would broaden the question. I have a martec and just llike the better feel of the flow of water over the rudder when near or at hull speed. I hard question to answer. I understand the boat should be kept in reverse when sailing with a fixed prop. Does the fixed prop strain / drag cause more wear on the transmission, cut less,strut? Is it offset by the vibration inherent in a martec compared to. The fixed prop. How is the boat affected while surfing a wave.

  3. #3
    Senior Moderator Loren Beach's Avatar
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    Lightbulb Prop Archives

    Lot of narratives and good info in this prior thread:
    http://www.ericsonyachts.org/infoexc...parisons/page2

    I still miss that last knot of speed and a degree or three of pointing.
    But everything's a compromise, they say.

    Adding another link:
    http://www.ericsonyachts.org/infoexc...&referrerid=28
    Last edited by Loren Beach; 06-11-2019 at 07:09 PM. Reason: more links
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  4. #4
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    At hull speed the fixed prop's drag isn't slowing you down really as the hull can only go so fast, but it IS inducing slip, so you're loosing a few degrees of upwind ability at hull speed. A big three blade prop can add about 150lbs of drag at hull speed. Try dragging a small bucket on a rope at speed. (note, use a really strong rubber bucket and cleat the rope off first...) A good slim two blade prop can be "only" 30 lbs of drag. A folding/feathering prop under 2lbs of drag. I prefer folding because I sail over a lot of lobster pots and don't want to catch them on a feathered prop.

    This article https://www.yachtingmonthly.com/gear...ler-test-29807 is the best I've read testing most of the popular folding/feathering brands.

  5. #5
    Moderator Christian Williams's Avatar
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    Thanks, they're all good links. A little embarrassing to find I asked the same question three years ago.

    And apparently I came to the same conclusion then: that I would gain little in my typical use.
    Thelonious II, E381 hull 513 (1984) Universal 5432
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  6. #6
    Makes Up For It With Enthusiasm Geoff W.'s Avatar
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    One consideration for us two-bladers, suggested to me by Bruce -- next time you dive / have your boat dived, fix your prop vertically so it's flush with the rudder, and then mark the shaft in position. Then when you go sailing, you can go down and rotate the shaft into position and lock into reverse so your two-blader is in as efficient a position as possible.

    Ballers on a budget.
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  7. #7
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    Just a bit off topic, but if anyone would like to change their 3 blade prop for an E38 to a feathering or folding prop, I would be interested in buying the old 3 blade from you
    Josephine, E381 hull 505 (1983) Universal 5432

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