Sealing a motor well?

Discussion in 'Sailboats' started by RHough, Dec 1, 2005.

  1. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    The Light Schooner I'm building calls for a 2hp OB motor mounted in a well. The motor tilts up though a hole in the bottom.

    I want to seal the hole while sailing.

    On other designs I've seen the OB is removed and a plug inserted to make the bottom fair.

    I'd like to devise a seal that will allow the motor to remain in place "ready for immediate use" rather than hang it off the transom.

    So far I've come up with two hinged "bomb bay" doors that would be held up with a lanyard while under sail and would be opened by the motor as it is tilted down. The doors would be buoyant and go over centre to lie against the hull while motoring.

    I'm open to ideas from minds more creative than my own. :)
     
  2. cyclops
    Joined: Feb 2005
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    Location: usa

    cyclops Senior Member

    Sounds perfect to me. " Bombs UP ". Just make damm sure that when the stern goes underwater EVERYTHING, is thru watertight bulkheads and fittings. Plus, when the stern lifts up, the doors absolutly stay open or closed as you had them set. Done correctly, the airpocket should last several minutes.
     
  3. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    The plug approach is really not that cumbersome, and the outboard can sit on top of it to hold it in place. It helps if the hole is tapered and of a shape that will only allow the plug to align itself one way. Take a look at a Hobie 33 to see one implementation of the plug idea.

    I've also seen a door that slid longitudinally to close the hole. It was pulled one way by a shock cord and the other way by a lanyard.

    A third solution is to bolt the door to the bottom of the outboard. If the outboard is on rails so it moves vertically, the door is always horizontal and presents a modest amount of drag. No worse than your bomb bay doors in terms of added wetted area.

    Don't forget the side loads on your doors when maneuering or in waves.
     

  4. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    Here's the rule:

    18.5 A boat with an outboard engine will receive the following adjustments to its rating.

    Outboard mounted on a bracket ready for immediate use with fuel tank connected: no Change

    Outboard mounted with propeller immersed: + 6 (seconds/mile)

    Outboard on board but not ready for use: -6

    No outboard: -9

    Can I argue that a plug that does not require that the engine comes of the bracket but must be removed satisfies "ready for immediate use"?

    On the other hand, will stowing the OB forward and plugging the hole make the boat faster enough to overcome the -6 rating hit?

    Of course I could just write the committee and ask for a ruling ... nah ... too easy :)
     
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