Hat Section Bulkheads? These I DO plan to install.

Discussion in 'Boat Design' started by CatBuilder, Dec 25, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    Have you all seen this type of bulkhead installed before?

    I finally hit on the right layout for our boat and it will involve making a little more open room. They use these in aircraft and in Gunboats.

    Any issues doing them?

    Are they always foam filled? Very light foam, I'd imagine?

    (Hat section bulkhead is located on lower left corner of the picture)

    [​IMG]
     
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  2. TeddyDiver
    Joined: Dec 2007
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    TeddyDiver Gollywobbler

    Either hollow or wood filling if you need to have bolts or screws..
    BR Teddy
     
  3. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    Looks like you could just foam fill to me, but I doubt you would even need to fill. Rick
     
  4. tunnels

    tunnels Previous Member

    What happens if you put a Thin paneled bulkhead Underload ??
    What is a bulk hulk head actually there for ??
    Is it structual ?
    if its not serving any useful purpose why even bother making it and putting in in at all ??
    Hollow ??
    weak foam??
    Why not just make it out of paper !!
    why bother ??:confused::(
     
  5. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    With three sides glass you would have a basic hat channel, counting the hull skin you would have four sides making it a box beam. Either of these would be structual in nature, how strong it is depends on size and material. Rick
     
  6. tunnels

    tunnels Previous Member

    Theres a million ways to make box beams that when placed under stress wont totally collaps or twist out of shape and become next to useless .Box beams is a whole science on its own . same when making hollow stringers or foam filled stringers . the height ,width and actual size and how its made is vitally important . with shaped sides a box beam can become a semi spring to absorb shock loadings . A beam that can absorb loads like a spring and returning to its origanal shape is a whole lot of fun to play with . Solid glass hull bottoms with very few frames but use long stringers that have a dregree of bend can be made to make the boat ride much smoother than a ridged hull with lots a frames and no flex at all .
    Along with flex twist is closely following . twist and flex can be made to be able to work together and make almost indistructable panels !!.Used in rescue work and life threatening situations panels can be designed in a way to progressivly distruct slowly and not simply snap and break like a carrot .
    Carbon is the worst carrot of all !! there one second and then gone completely the next !!,so has no place here !
    Glass on the other hand will hang on and hang on for a long time before finally saying bye bye .
    Used to make surf boats that were light strong flexable and would twist .Most of the chractoristics of a soft bottom boat but the added advantages of a ridged with highter speed and beter manuoverability , and not slipping and sliding every where .
    The Boat crew could have legs broken and sprained ankles with cracked ribs after riding and getting caught in really rought huge waves but the boats could land back on the beach with over a ton of water inside and never burst open or break or have any visable signs of stress or damage !
    Never used any fancy resins and just 2 simple types of Glass that nearly every supplyer has heaps of on there shelves . The secret is in how you use those two types of glass !!
    its not engineering its not rocket science ,Its impossibe to computerise a program for , its just plain good old common sense! and know how !!!:D
    Most important!, understanding the capabilities of the materials you are working with !
    What you can do and what you cant do !
    what you should do !and what you shouldnt do !

    .
     
  7. sorenfdk
    Joined: Feb 2002
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    sorenfdk Yacht Designer

    I don't see a bulkhead in the lower left corner! What I do see is a frame.
     
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  8. eyschulman
    Joined: Jul 2011
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    Location: seattle Wa USA

    eyschulman Senior Member

    At some point when a ring bulkhead gets cut out enough it must become a frame and if it goes all around the structure is that then a ring frame?
     
  9. sabahcat
    Joined: Dec 2008
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    Location: australia

    sabahcat Senior Member

    Bollocks.

    I have seen this sort of thing done on 40 fters with white, non-structural polystyrene with a heavy uni cap and then 2 staggered layers of 800gsm biax
     
  10. CatBuilder

    CatBuilder Previous Member

    I've seen them done on 66 footers the same way you mention as well. The picture above is from a Gunboat 66. One of the best offshore catamarans made. No doubt as to the seaworthiness there.

    I wonder how many bulkheads can be replaced this way? Could I do 2 in a row, not including the real structural ones?
     
  11. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    And I have seen hobos to drink denatured alcohol but wouldn't do that either :p
     
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  12. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Yes, all if you want to, but you have to know scantlings for these beams, becouse that's what they are structurally. Some of these members replacing bulkheads can also be fixtures working as additional beams or stringers laminated btw the beams.
    The stryrene Saba mentioned can be used to shape the section in place especially if you need to make a kinky shaped one. However it doesn't have any stuctural purpose (styrene).
     
  13. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Hat section ring frames are very common. Simply get the scantlings correct.

    Im watching a chainplate ring frame being retro fitted to 25 footer now. Its a two halves...port , starboard frame. Most of the actual fabrication is being done in the workshop. The frame , once finished , will then bonded into the boat.
     
  14. tunnels

    tunnels Previous Member

    You got it . We had patterns and made everything on the bench including the placement of the uni layers the ran round the inside and were glassed over . Had one team set up to bag and make all the frame work and deliver to the boat at the right time including the longtudinall framing as well with large cut outs on the insides .
     

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  15. CatBuilder

    CatBuilder Previous Member

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