Sea Sled madness. It’s in my brain.

Discussion in 'Fiberglass and Composite Boat Building' started by DogCavalry, Nov 11, 2019.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    Ok...with what you have, this suggest the following:

    upload_2021-4-25_10-22-24.png

    You have the apex, but what is supporting it along its length?

    As this goes aft, if those long.ts become as noted in yellow...not much, the the solution is as to introduce another long.t, noted in red. However, this is to start in the void fwd of this.
    Reason is, as Fallyguy notes, you'll get a sudden major change in stiffness which leads to stress concentrations at this bhd.

    Thus by starting this long.t in the void fwd of where you need it..it provides the structural continuity across that 'weak' transition from the girder to that the small region, noted in yellow.
    So that part becomes stiffened and supported by the new girder/long.t shown in red which has greater stiffness before and after that bhd transition.

    Does that make sense?
     
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  2. DogCavalry
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    DogCavalry I aim to misbehave.

    It does. Thanks!
     
  3. fallguy
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    fallguy Senior Member

    Not sure I understand.

    floors every 8-11"?

    I thought you asked about spans a bit ago.
     
  4. DogCavalry
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    DogCavalry I aim to misbehave.

    Hi Fallguy. I'm trying to get the strongest cockpit area structure consistent with the rest of the hull. Talking with you guys has made me realize the vulnerability of the sudden loss of strength from one side of a bulkhead to another.
     
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  5. fallguy
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    fallguy Senior Member

    Another question/poi t of clarity.

    Does the tunnel apex always touch the sole as by the step, or are you walking away from the sole as you go aft?

    Isn't there some practicality to supporting the center as well? Just that you get stiffer walkway and structural support.

    it is a question..
     
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  6. DogCavalry
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    DogCavalry I aim to misbehave.

    I could build something massive between B2 and B3, but if the interior remains the same, that becomes the new week point.
     
  7. DogCavalry
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    DogCavalry I aim to misbehave.

    The tunnel apex only touches the sole in that 1 spot. Generally there's at least 3 or 4 inches clear.
     
  8. DogCavalry
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    DogCavalry I aim to misbehave.

    With the strip plank composite structure, there is already a lot of fore and aft strength, from the planking. The technique's weakness is across the grain, so Gerr stresses transverse bulkheads. And interior glass.
    I haven't decided details inside the cabin yet. So I don't know how I'll do the interior sole, just where it will be.
     
  9. DogCavalry
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    DogCavalry I aim to misbehave.

    So these longitudinals I've decided to install, for the 3 spaces within the cabin, can they run at a slight diagonal rather than strictly fore and aft? I'm thinking to carry them from the inside of B3 where they are about 3' apart, back to B6, where the 1" thick plywood long.ls run from B6 to the transom, and are 4' apart.
     
  10. DogCavalry
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    DogCavalry I aim to misbehave.

    More glass this weekend. Still marvelling at the notion that I'm "the best in the yard". I see a lot of work on the forum that's better than mine.
     
  11. fallguy
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    fallguy Senior Member

    A bit unconventional.. but seems okay to me.
     
  12. Ad Hoc
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    Ad Hoc Naval Architect

    They can, as they are still long.ts.
    But it may complicate fabrication...thus what is the purpose of having them run diagonally?
     
  13. DogCavalry
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    DogCavalry I aim to misbehave.

    There are 2 longitudinal bulkheads under the sole between the transom and B6. Landing the longitudinals on them seems reasonable.
     
  14. fallguy
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    fallguy Senior Member

    Pictures?
     

  15. DogCavalry
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    DogCavalry I aim to misbehave.

    20210220_133344.jpg
    Like this.
     
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