how deep should a transom be to hold 200 horsepower engines and up?

Discussion in 'Powerboats' started by Islandboy, Apr 5, 2006.

  1. Islandboy
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    Islandboy Junior Member

    i need some help
     
  2. marshmat
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    marshmat Senior Member

    Care to elaborate? What is the situation you're talking about?
     
  3. Guillermo
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    Guillermo Ingeniero Naval

    Power (For planning boats) is more related to breadth astern than with deepness of hull there. Could you be more specific about your question?
     
  4. Islandboy
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    Islandboy Junior Member

    ok ive designed a NEW boat hul that has never been made and i jus need to know the calculations of certain parts of the boat its a planning hull more of a power skiff i need to know if the transom have to be a certain measurement to hold a engine over 200 horsepower
     
  5. dougfrolich
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    dougfrolich Senior Member

    hmmmm. I think a better question might be; What should the LCG be for the speed I expect to achive for a given horsepower, chine beam, dead rise, lwl and displacement.
     
  6. Willallison
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    Willallison Senior Member

    I think what Islandboy means, is how thick does the transom need to be.
    I don't have the info here at work - but someone else may do. There is much more to engineering a hull structure than simply the thickness of the transom however...
     
  7. gerard baladi
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    gerard baladi Junior Member

    Go to marinepower.com, they have diagrams of engine installation requirements for various o/b (surf through the downloads)
     
  8. fede
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    fede Senior Member

    Transom for most Mercury sterndrives has got to be between 51 and 57 mm.
     
  9. Ike
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    Ike Senior Member

    I think he wants transom height. Most outboard motors have a standard shaft length of 20 inches (50.8 cm). So your transom height from the bottom of the hull to the top of the transom where the motor mounts, should be 20 inches (50.8 cm) for most outboards. However, these big block outboards generally have a long shaft. I looked on Mercury's site for the shaft length of their 225 EFI Four Stroke. It's 25 inches (63.5 cm) or you can specify a 30 inch (76.2 cm) shaft. Yamaha is the same for their 225 fourstroke. I would go for 25 (76.2). All the outboard manufacturers usually use the same standards shaft length so this should accommodate any 200 HP or up outboard
     
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  10. Ike
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    Ike Senior Member

    Oops, I goofed on my metric conversion. 25 inches is 63.5 cm. I've got to proofread before I post!
     
  11. antonfourie
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    antonfourie Senior Member


  12. dereksireci
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    dereksireci Senior Member

    Boats under 20'

    CODE OF FEDERAL REGULATIONS – TITLE 33 – NAVIGATION AND NAVIGABLE WATERS

    PART 183—BOATS AND ASSOCIATED EQUIPMENT

    Subpart D—Safe Powering

    ((Length of boat in feet x width of transom in feet) x 2) - 90 = max HP

    For a boat with remote steering and transom height 20" or more

    http://www.uscgboating.org/safety/boatbuilder/part1/reg33_183_4a.htm

    djs
     
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