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  1. #1
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    Jun 2019
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    2008 Crownline 21SS LPX - need prop help

    Hey guys.....first post here. I just picked up a new to me Crownline 21SS LPX pkg. (their semi performance runabout) with 350 Mag MPI (300hp) and 1.47:1 Alpha one outdrive and Corsa Capt. Call exhaust. Currently it has a Stilletto 14.25"x 21p prop (E800321).

    I'm not new to boating, just stern drives. Ive had a few high performance bass boats that would run triple digits (Allison & Bullet) with 280+HP Mercury Racing outboards. I was very in tune with propping those and extracting best performance.

    I bought this in lieu of a Caravelle Interceptor 212 that I've always wanted. Its a sharp boat, but I'm still looking for the right Interceptor.

    Its a dog out of the hole and the Stilletto has pretty much no bow or stern lift. Pegs 25-2600 RPM WOT coming out of the hole and its a turd. Trim is almost ineffective once on plane.
    Thats 40 gallons of fuel, me, my wife and daughter; About 470# for the 3 of us.

    Trimmed out, it pegs at 51/52mph gps at 3800rpm. No trim does 44-46. I see no reason why this boat can't do high 50's loaded. I'm concerned my tach is inaccurate as the math does not add up.

    I need to know if I am expecting too much lift from this rig. Yeah.....its like 3600#, but it always feels stuck to the water. I can trim it and it slightly increases RPM, with no bow rise or stern lift. It will never porpoise, even at full trim.
    This thing just always feels glued to the water like a v-drive.

    I don't expect this thing to drive or run like my Bullet or Allison, but I do feel like it has more potential.

    I'm not scared to drop the coin on an Enertia or similar if you guys feel thats the solution.

    The reduced diameter worries me as diameter is directly related to the props ability to carry a load, but the Enertia seems to be the exception to the rule.

    Thanks in advance for any advice.

    Last edited by 00bullitt; 06-11-2019 at 11:09 AM.

  2. #2
    Join Date
    Feb 2014
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    I’m sorta familiar but all I know run bravo and don’t really go after performance but I do think iirc you should be turning closer to 4800. Year and displacement have a lot to do with that.

    Mat 50 you can expect to lift a strake or two but you won’t get all the way down. Good water repelling wax and speed coat will help.

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