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  1. #1

    1050 MANS in a 46C

    Anyone know who this is? Copied from boatdiesel. Incredible numbers. He's looking for advice on how to stop the chine walking. I told him to contact Tom Slane, SAMS, or Jarrett Bay. His screen name is Cruzcol.

    "I just repowered my 1981 Hatteras 46 S.F. with 1050 hp, 10 cylinder, MAN engines. Here are the result of the sea trial with 30 x 31 DQX, no cup ,4 blades propellers, 2 1/2 inches shafts

    1000 RPM - 12 knots
    1300 RPM - 16-17 knots
    1600 RPM - 23-24 knots
    1800 RPM - 28 knots
    1900 RPM - 29 plus knots
    2300 RPM - 35 plus knots

    When we reached 28 knots, the boat started to lean to the port side and when we reached 35 knots it was too much so we slowed down. The trim taps were all the way retracted (not working) so we could not use them to correct. No idea why it was leaning to the port side. Please comment."
    Last edited by fissioneng; 10-09-2009 at 08:11 AM.
    Looking for another boat...not a Hatt

  2. #2

    Re: 1050 MANS in a 46C

    Thats just too much HP for that hull.

    Adding lift and spray rails with the tabs working would probably do some but there is a question of how much HP is too much.
    Scott
    41C117 "Hattatude"
    Port Canaveral Florida.


    Marine Electronics and Electrical Products Distributor.

  3. #3

    Re: 1050 MANS in a 46C

    he needs to reduce the flat surface area of the keel. Either cut it down like the 46HP or you have to round it off. The boat is getting up out of the water and riding on the keel like its a water ski. They usually come up, feel unstable and then fall over to one side. If he is leaning over then maybe there is a weight distribution issue. Once he gets this squared away, I'd expect even faster speeds.
    Jack Sardina

  4. #4

    Re: 1050 MANS in a 46C

    Quote Originally Posted by saltshaker View Post
    he needs to reduce the flat surface area of the keel. Either cut it down like the 46HP or you have to round it off. The boat is getting up out of the water and riding on the keel like its a water ski. They usually come up, feel unstable and then fall over to one side. If he is leaning over then maybe there is a weight distribution issue. Once he gets this squared away, I'd expect even faster speeds.

    I have spoken to others about that and the consensus was the shaving of the keel was a last resort. Maybe an edge on it to prevent the lift would work better as it allows it to cut through the water but still maintain the integrity of the vessel. I still stand by the statement that the HP may just be too much. I ran one long ago and remember it was quick with about 1250 HP or so. 2000+ seems a bit over the top.
    Scott
    41C117 "Hattatude"
    Port Canaveral Florida.


    Marine Electronics and Electrical Products Distributor.

  5. #5

    Re: 1050 MANS in a 46C

    What about sharpening the lowermost edge of the keel so that it doesn't offer any planing area? That way, he'd get to keep the side area of the keel which does have some benefit in crosswinds etc, and for tracking.

    It does sound like an awful lot of power to go in that boat. A newer 45C will go that fast with 600 hp per side- this is nearly twice that.

    Years ago Tom Slane built a 45C (69 or 70 hull) with V10 MANs but not at that power rating. And it was nearly that fast, but he modified the bottom to stabilize it, I think. Calling him might be helpful.

  6. #6

    Re: 1050 MANS in a 46C

    Quote Originally Posted by fissioneng View Post
    Anyone know who this is? Copied from boatdiesel. Incredible numbers. He's looking for advice on how to stop the chine walking. I told him to contact Tom Slane, SAMS, or Jarrett Bay. He screen name is Cruzcol.

    "I just repowered my 1981 Hatteras 46 S.F. with 1050 hp, 10 cylinder, MAN engines. Here are the result of the sea trial with 30 x 31 DQX, no cup ,4 blades propellers, 2 1/2 inches shafts

    1000 RPM - 12 knots
    1300 RPM - 16-17 knots
    1600 RPM - 23-24 knots
    1800 RPM - 28 knots
    1900 RPM - 29 plus knots
    2300 RPM - 35 plus knots

    When we reached 28 knots, the boat started to lean to the port side and when we reached 35 knots it was too much so we slowed down. The trim taps were all the way retracted (not working) so we could not use them to correct. No idea why it was leaning to the port side. Please comment."

    He is a member here, he is Alfonso Cruz Colon in Puerto Rico.

    Shaving the keel is the answer. My 46C HP would do 33 kts when new and has the factory cut down keel and the boat was steady at speed.

    This subject has been discussed at length before.

  7. #7

    Re: 1050 MANS in a 46C

    Good to know. I posted a message to tell him to come look at the HOF.
    Looking for another boat...not a Hatt

  8. #8

    Re: 1050 MANS in a 46C

    Throttle stops.
    I like a lot of the designs from the 1960's and 70's and believe the GTO a better car than the Tempest, but boat design is a bit more complex. I suspect that a Hatteras 46 modified to tolerate 35kt+ will not be as good a boat.
    Vincent

  9. #9

    Re: 1050 MANS in a 46C

    DO NOT SHAVE THE KEEL!!!! I own a 1980 50c w/ 2842 12cyl 1360 mans D rated to 900hp. The chine walk is due to the beam... not skiing on the keel. The way to stabilize the "walk" is to increase the beam. Strakes, lifting chines etc... The other way, much more to my way liking is to cruise at 26kts and be happy with the economy. By the way if you fish seriously you're gonna love the MAN Diesel "drumbeat" at trolling speed.. these engines Raise fish and are incredible.
    50c-1980-DYLAMAR

  10. Re: 1050 MANS in a 46C

    Square peg placed into round hole.

    That's an INSANE amount of power in that boat. I hope there was some nautical engineering work done on the forces involved BEFORE those engines were put in the hole or you might get an ugly surprise one day.....

    I would not shave the keel. Yes, you can, but......

    I'd have a GOOD naval architect look at this one. The boat is getting too far out of the water on plane. Some sort of alteration of the in-water part of the hull has to be undertaken, but this is NOT to be done lightly as these sorts of changes can destroy the running character of the hull quite easily.

    Get QUALIFIED help.
    http://www.denninger.net - Home page with blog links and more
    http://market-ticker.org - The Market Ticker

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