Hard chine Runabout for 20hp outboard

Discussion in 'Wooden Boat Building and Restoration' started by Graham Tapper, Mar 14, 2020.

  1. Graham Tapper
    Joined: Mar 2019
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    Location: Devon UK

    Graham Tapper Junior Member

    My 2020 project was begun in January and here is my progress report as of Saturday 14th March 2020. Still upside down on the jig having spray rails fixed to the bottom panels and chine. The aft section of the keel band is glued and pegged in place with dowels.

    COM_8026.JPG
     
  2. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    What is the design?
     
  3. Graham Tapper
    Joined: Mar 2019
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    Location: Devon UK

    Graham Tapper Junior Member

    The design is my own but aspects are taken from several different types of runabout including the Classic Albatross, Glen-L zip and the RIB. An outboard moter well will be incorporated to the transom. The first aproach was then to fabricate a model half mould to 1/8th scale from which all the measurements were taken off to scale up. I have a Blog site where you might like to take a look at these earlier stages from start to finish:- Head for the Hills http://moggo-blog.blogspot.com/.
     
  4. fallguy
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    fallguy Senior Member

    Been wondering where u went. I figured you were down the Thames by now. Keep posting.
     
  5. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Graham, the picture indicates that the chine has lifted above a straight line, at the near corner of the transom. If that is a structural element of the boat, that which the picture suggests, then you will lose some of the potential planing force that the 20 HP motor might have provided.

    If you meant for the boat to be a semi displacement one, then some moderate aft rocker would have been more nearly conventional.
     
  6. Yellowjacket
    Joined: May 2009
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    Yellowjacket Senior Member

    What is the estimated weight of the basic hull (not including motor or occupants). And how fast do you expect this rig to go?
     
  7. fallguy
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    fallguy Senior Member

    pay attention here Graham; looks fixable with fairing compound if u r painting it
     
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  8. Graham Tapper
    Joined: Mar 2019
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    Location: Devon UK

    Graham Tapper Junior Member

    Estimate hull will weigh in the region of 100kilo but outboard is 68kilo to add on. As for speed potential I expect 24mph or so dependant on how well the spray rails are effective.
     
  9. Graham Tapper
    Joined: Mar 2019
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    Location: Devon UK

    Graham Tapper Junior Member

    More progress to report for those interested in this little 12'8" runabout.
     
    BlueBell likes this.
  10. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Graham that is a good looking little runabout. It does have a feature that may (or may not) cause some unpleasant surprises. The reverse chine....I think that you are calling them spray rails, could cause a problem that is sometimes described as "hooking". If the boat banks inward, reliably, when making a turn, then all is well. If it does not bank sufficiently to raise the spray rail above the water surface it will tend to "hook' in the water and overturn the boat toward the outside of the circle. That feature is somewhat larger than would be conventional on such a small boat.
     
  11. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Hi Graham,

    I'd say leave 'em as is and take it easy on the throttle when you sea-trial.
    You can cut them off if they prove problematic.
    Or modify them...

    Great project.
    Carry-on, before the virus gets you! (Reference, your video :)
     
    DogCavalry likes this.
  12. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    I doubt it will cause any problems, in fact might be helpful, this is supposedly a pretty light boat, and there is enough deadrise to have it banking in turns.
     
  13. Graham Tapper
    Joined: Mar 2019
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    Location: Devon UK

    Graham Tapper Junior Member

    Progress at 29th March - May be slowed up by lockdown during pandemic but am soldiering on regardless till I run out of materials.
     
  14. Graham Tapper
    Joined: Mar 2019
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    Location: Devon UK

    Graham Tapper Junior Member


  15. Graham Tapper
    Joined: Mar 2019
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    Likes: 21, Points: 8
    Location: Devon UK

    Graham Tapper Junior Member

    Dejay likes this.
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