catamarn with stern drive engine

Discussion in 'Boat Design' started by chaser, May 23, 2012.

  1. chaser
    Joined: Jun 2009
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    Location: CHINA

    chaser Junior Member

    i have build a catamarn boat,yesterday we had a sea trial,but the stern spoodrift is terrible,and the engine is 2*220hp,displacement is 12T,but the engine can't reach the rated revolution ,it is means the boat is too heavry ,but in my opinion the spoodrift doesnt make any sense with the displacement, i dont know where is the problem.
    Last edited: May 26, 2012
  2. Frosty

    Frosty Previous Member

    What is a spoodrift? what RPM are your getting now.
  3. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    What rpm are you getting, what speed are you getting, what are you expecting? Not a whole lot to work on from what you have told us.
  4. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    If these pictures were made with the engines fully trimmed in, there is something very wrong with the stern angle and/or weight distribution.
    Install a large adjustable trim plate between the hulls to correct the problem. That will not make this boat a prize winner, but at least make it usable.
  5. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    尾部, 船尾, 臀 | a. 严厉的, 严格的, 坚定的, 坚决的
    整齐, 情形, 修剪 | a. 整齐的 | vt. 使整齐, 整理, 修剪 | vi. 调整, 见风使舵 | 【计】 库存管理检查规则程序 | 【化】 密封面; 微调 | 【经】 回档整理

    I think maybe the trim of the legs is not adjusted or that boat12T could be tooo heavy, How long is it? 浪花
  6. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    plenty of bow lift and no stern lift...looks like an experiment
  7. Frosty

    Frosty Previous Member

    I dont think there is bow lift --you are being confused by the paint job , look at the top of the cabin it is horizontal and who said it had trimable drives on it.

    Shall we wait till he gives more information.
  8. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    Chaser please post pictures of the boat out of the water so that we can see the hulls and the drives and propellors

  9. davhill
    Joined: May 2012
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    Location: Massachusetts

    davhill Junior Member

    Possibly "spoondrift", variant of "spindrift", e.g. "spray", e.g. "roostertail."

    I think he means "I have this big damn roostertail and no get up and go."

    1 person likes this.
  10. APP
    Joined: Nov 2010
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    APP Junior Member

    Can you describe in some detail this adjustable trim plate between the hulls? It can be a good idea for new designs as well.
  11. BPL
    Joined: Dec 2011
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    BPL Senior Member

    Chaser wrote "catamarn with stern drive engine." Aren't all stern drives trimable now?
  12. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    I do not think it is a catamaran, but more like a mono with sponsons attached to make an "almost Cathedral" hull shape - and an abortionist one at that (dead on birth)... One needs to see more to make any sensible assessment...

    - - A 28ft powercat (Australian design) with a pair of 100hp volvo sterndrives will do an easy 20knots heavily loaded with 500kg of fish and 700kg of ice-brine and that was way back in 84... Sack the designer and start afresh...
  13. Frosty

    Frosty Previous Member

    All drives are on the stern. The rooster looks like cavitation but cant be if RPM is low.

    Poor pictures, poor English and no come back,--- either its a wind up or he doe'snt care.
  14. chaser
    Joined: Jun 2009
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    Location: CHINA

    chaser Junior Member

    the rated revolution is 3800 rpm,but now is just 3300rpm

  15. chaser
    Joined: Jun 2009
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    Location: CHINA

    chaser Junior Member

    thanks for you reply,because i am stay in china, we have the time difference.
    due to the stern drive engine was installed on a round bilge forms,it is diffculted to place the trim tab on the transom, i want to change the stern drive engine with a propeller shaft system.maybe the stern spoodrift could be better.
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