3 Blade Prop

Discussion in 'Catalina 30' started by Jac123, May 3, 2019. Add this thread to a FAQ

  1. Jac123


    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    I'm 90% set on installing the most efficient (for stopping and motoring)
    fixed 3 blade prop on my "89" 30' as available. Engine is M25xp/ 2:1
    Any info is appreciated

  2. markwbird


    Joined Nov 26, 2012
    999 posts, 235 likes
    Hunter 34
    US Berkeley
    The engine and / or prop manufacturer should be able to answer that for you.

  3. The Shadow Knows

    The Shadow Knows

    Joined Jun 10, 2017
    148 posts, 59 likes
    Catalina 1980 Catalina 30 Mk II
    US South Pasadena / Tampa Bay

    I went thru the same years back, I had an old 5411 with a 2 blade folding prop
    that I changed to a 2 blade (same pitch) fixed prop. I had no experience of the forces & how the worked at the time.

    A boats horsepower at the flywheel is very different from the HP at the prop.
    Depending on prop length, the HP from flywheel to the prop diminishes greatly.

    Example: my 5411 HP was only 6HP at the prop at full throttle.
    I couldn't even get out of my way. I put in a 3M-20A & did this test. I found
    this can be done at the dock or while underway.

    Simply put, if your wide-open throttle does not reach MAX RPM's as described in the engine manual, you are over-pitched. If exceeding max RPM's, you are under pitched.

    My first offshore trip to Key West was arduous to say the least. Between current wind-n-wave, I was lucky to get 3-4 KTS. I did the prop change in Key West &
    unlike my trip down, I flew back!.

    Do the test & contact the manufacturer for the recommended diameter & pitch for a 3-blade.
    Then contact a local prop guy to see what he says. Then decide on the prop.

    I now have a kick-ass 3 blade & sometimes, I feel like I'm a powerboat up on a plane!

    Hope this helps.........

    Last edited: May 3, 2019
    Jac123 likes this.
  4. David in Sandusky

    David in Sandusky

    Joined Nov 8, 2007
    1,160 posts, 186 likes
    Hunter 27_75-84
    US Sandusky Harbor Marina, Lake Erie
    Check out Campbell Sailor props. They will spec a prop for you, and guarantee the pitch is right.

    Ours operates in a whole different range of efficiency than our two bladed prop. Added about a knot to our cruising speed.

    Jac123 likes this.
  5. Benny17441


    Joined May 24, 2004
    5,749 posts, 417 likes
    CC 30
    US South Florida
    Everything is a compromise. A three blade prop will provide more drag under sail than a two blade prop. They do reduce prop walk and better low speed capabilities. Before making a decision check the percentage of time you spend motoring vs. under sail. If you motor less than 20% of the time I would not bother.

  6. jssailem


    Joined Oct 22, 2014
    9,006 posts, 3,921 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    I had a 3 blade Michigan Wheel.
    I replaced it with the shaped Campbell Sailor by “North by West” in Comox BC.
    KELSEY helped identify the best size and pitch for my boat based on the boat, the motor, and the transmission.
    Results 1.5 knots faster under power. I reach hull speed at 95% of WOT.
    .8-1 knot better sailing speed.
    No prop vibrations when surfing on a swell.
    Less prop walk.
    I am very pleased wiling the new prop.

    Jac123 likes this.
  7. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    1,207 posts, 649 likes
    Beneteau First 38
    Ca Lyall Harbour Saturna Island
    :plus: Campbell Sailor

  8. Stan Galper

    Stan Galper

    Joined Jun 3, 2004
    12 posts, 1 likes
    Catalina 30
    US Port Charlotte, FL
    13X10 (13" Diameter 10" pitch) 3-blade give the best motoring performance for an M25XP. Feathering props give the best combination of power and sailing speed, but they cost a lot more than fixed blade props.

    Jac123 likes this.
  9. Kingjim91


    Joined Jul 6, 2013
    106 posts, 7 likes
    Catalina 30TR
    US Milwaukee
  10. jssailem


    Joined Oct 22, 2014
    9,006 posts, 3,921 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    @Kingjim91 Those props are good props. They are known as "Michigan Wheels" and make up a major proportion of the 3 bladed fixed props on sail boats or power boats. Two reasons. Large production and reasonable costs.

    The big ears (blades) on these props contribute to two of the often voiced problems with boat handling. Prop Wash (or Walk) and reduced sailing speed due to prop drag.

    In order to address these perceived weaknesses, boat owners have chosen alternatives. Popular are the folding or rotating props that greatly reduce prop drag by causing the prop to feather into the water stream. It works in the same way as a prop plane feathers the prop to point the blades into the wind reducing the drag.

    Another alternate is based on reshaping the prop blade. The CampbellSailor takes this approach.

    Which ever path the SBO takes it is a compromise. The fast way to sail is to have no prop in the water.

  11. Kingjim91


    Joined Jul 6, 2013
    106 posts, 7 likes
    Catalina 30TR
    US Milwaukee
    Thanks for that good info, jssailem.

    jssailem likes this.
  12. jeff356


    Joined Apr 21, 2014
    135 posts, 25 likes
    Hunter 356
    US Middle River, MD
    :plus:Campbell Sailor Prop, went to fixed 3 blade from standard fixed 2 blade and way smoother, good power and backs down well. Also company great to deal with.

    jssailem likes this.

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