I built a deer island 28 by brewer a couple decades ago

Discussion in 'Boat Design' started by needanotherboat, Aug 8, 2017.

  1. needanotherboat
    Joined: Sep 2013
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    needanotherboat New Member

    It had a keelson, a partial keel, lots of longitudinals, 3/4 ply bottom, 5/8 sides, bulkheads. IM looking at building a Tollman Jumbo and trying to relate the scantlings /structure. The tolman has a much higher speed ratings it is much more lightly built. IS it that thing where the heavier it is the stronger it needs to be?. The deer Island went 20 with a 260hp diesel. I'm thinking / wondering what if I built the deer Island with similar scantlings as the tollman then maybe brought it close to its line with a little ballast low at the keel? was the Deer Island over engineered? With modern epoxy and fiberglass could it be better?
     
  2. TANSL
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    TANSL Senior Member

    The scantlings of a ship depend on many factors, so it should never be assumed that the scantlings of a ship are suitable for those of a ship of another type. Some calculations have to be made, though not many. Even two vessels of the same type and dimensions, with different structural arrangements, may have very different scantlings.
     
  3. tom28571
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    tom28571 Senior Member

    The Tolman Jumbo is less than half the displacement of the Deer Isle 28. That is a clue that it may need greater scantlings. Speed and power are considerations as well. Trust the designers, both of which are well regarded, or trust yourself to make any reasonable changes. A Dave Gerr Offshore 28 is a much more legitimate comparison to Ted's Deer Isle 28.

    edited: Oops, I meant to say the Offshore 28 and Tolman are more similar in scantling requirements.
     
    Last edited: Aug 8, 2017
  4. needanotherboat
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    needanotherboat New Member

    I should revise what I am c0mparing. I am looking at a tollman jumbo stretched or a Great Alaskan 28ˋ, both 8´6 beams vs the 9´6 beam of the the deer Island 28. My real question is could one eliminate the frames replacing them with bulkheads and molds, the goal being to have a cleaner interior with more space.

    I just look at the two and the deer Island seems overbuilt with all those 5/4 frames. The hull thicknesses are basically the same, the longitudinal are not a problem.

    The goal is a trailer trawler to sleep four
     

  5. tom28571
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    tom28571 Senior Member

    I would not venture to significantly alter Brewer's scantlings myself. Ted has retired from boat design and now plays with model trains but he is still active and you should contact him. I do agree with your wish to get rid of as many transverse frames as possible for a cleaner interior. My boats have no frames at all and depend on bulkheads and longitudinals for strength and rigidity.
     
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