Building hull in cross sections

Discussion in 'Multihulls' started by SmallSpaceBigImagination, Mar 22, 2021.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    I guess I'm thinking something that could easily be disassembled again, welded structures are not in that category. Maybe someone will come up with a flat-pack kit boat, Ikea furniture type of thing.
     
  2. Barry
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    Barry Senior Member

    The OP wants to build sections, store them and then assemble them. He did not mention that he wants to take the boat apart at a later date. Being able to weld the sections together at assembly time is fast, can be fair
    and get yield strengths over 10,000 pounds per square inch.

    The frames at intersections could be bolted, then welded.

     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    I well understand that metal is the most likely candidate to build in sections, where space is limited, and assembly has to be done elsewhere, but he did not specify materials, and perhaps he can indicate his intentions with that. Obviously though, aligning accurately and welding it together, sounds more exacting than bolting together, or some other method of slotting it all together.
     
  4. guzzis3
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    guzzis3 Senior Member

    As others have said how big a boat do you want to build ?

    As also said section hull builds have been done. But again as said once you assemble your hull, I assume somewhere you will be paying rent, you have to fitout. You can build a hull quickly. Finishing and fitout takes a lot longer.

    Easy enough to do it in foam but you probably won't be able to take it apart again.

    And I'll repeat: How big are you talking ?

    19x7. So build half a hull 15x4. That gets you 30' long in 4 pieces. Build the bridgedeck in 2 pieces, and beams. Rent a space and glue these 4 bits together add beams etc. The problem is now you need to fit out, although some of that might be done while the hull is in 6 pieces, plus beams.

    Richard Woods has a range of power cats in flat panel.

    Sailing Catamarans - First Choose a Design http://sailingcatamarans.com/index.php/designs-2/6-powercats
     
  5. SmallSpaceBigImagination
    Joined: Mar 2021
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    SmallSpaceBigImagination Junior Member

    19x7. So build half a hull 15x4. That gets you 30' long in 4 pieces. Build the bridgedeck in 2 pieces, and beams. Rent a space and glue these 4 bits together add beams etc. The problem is now you need to fit out, although some of that might be done while the hull is in 6 pieces, plus beams.

    Richard Woods has a range of power cats in flat panel.

    Sailing Catamarans - First Choose a Design http://sailingcatamarans.com/index.php/designs-2/6-powercats[/QUOTE]

    I found Sailing Catamarans - Skoota 32 demountable version https://www.sailingcatamarans.com/index.php/designs-2/6-powercats/483-skoota-33 which lets me fit out the cabin in 1 build. Hull sections will probably be fitted out in sections too. Faring up to 6 inches away from the joints
     
  6. SmallSpaceBigImagination
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    SmallSpaceBigImagination Junior Member

    Always wanted to learn to weld. Does the type of welding influence the strength (Tig/Mig/Stick)?
     
  7. SmallSpaceBigImagination
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    SmallSpaceBigImagination Junior Member

    all True... sadly I've not been successful in finding a diy yard close to where I live. Also storage while the boat is being worked on in a marina won't sit as well with the wife as storages of boat pieces @ my brother/sister/buddy's garage would :)
     
  8. SmallSpaceBigImagination
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    SmallSpaceBigImagination Junior Member

    You got it... Single car garage. I can expand 7 ft to 9 ft and still have walking area. I'm not fortunate like my siblings to have 3 car garages. Like the tacking idea... I doubt I could create a water tight weld.
     
  9. Barry
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    Barry Senior Member

    You would be using Mig on this. Regarding strength loss due to welding. Many if not most "marine aluminum" referenced alloys go through a hardening or temper process to modify characteristics.
    When welding, the area that gets hot due to welding, and the strength at the weld gets to a zero treated/hardened alloy. Tensile strengths still over 10,000 psi.
    Regarding can you weld an aluminum boat yourself without experience, probably not, but you would be able to tack weld, ie 3/4 to 1 inch welds to hold the parts together for fitting, etc.
    An experienced welder would then begin sequential welding, and when he gets to a tack, he would grind it out so your quality of weld or lack there off, is mitigated.
     
    Last edited: Mar 23, 2021
  10. guzzis3
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    guzzis3 Senior Member

    Don't build in aluminium. I was a master welder when I was young, used to practice my oxy acetelene welding on aluminium cans, but welding aluminiun properly is tricky. Even if you get it watertight knowing it's structurally sound is tricky. Your hull can crack open or even break at sea.

    Plywood or foam sandwich. Simple and inherently water resistant.

    Email RW about building the demountable scooter hulls in 2 halves. You still haven't told us how big a boat you need.
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    He was talking about a motor cat 17 feet wide, so I am thinking around 38-40 feet, guzzis3
     
  12. gonzo
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    gonzo Senior Member

    If you build with a method like "Constant camber" it would give you the opportunity to have all the panels pre-made and also the cabinetry, which takes most of the build time.
    When you are ready to assemble it, you should have some help and at least a couple of free months, at which point the rent wouldn't be too unreasonable. It will certainly not be more expensive than docking the boat; an expense you need to plan for.
     
  13. redreuben
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    redreuben redreuben

    I found Sailing Catamarans - Skoota 32 demountable version https://www.sailingcatamarans.com/index.php/designs-2/6-powercats/483-skoota-33 which lets me fit out the cabin in 1 build. Hull sections will probably be fitted out in sections too. Faring up to 6 inches away from the joints[/QUOTE]

    Guzzis3. 19x7
     
  14. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    The harry proa designs reuses the hull molds for vacuum infusion potentially 8 times. The smaller hull is just 4 pieces of one horizontally split "quarter hull mold". The longer hull uses the same mold as the smaller hull but puts a straight hull in-between.
    Of course this has design limitations, and I'm not quite sure if the E25 is actually build the same way as the C50. The tender is build with longer vertical half molds.

    [​IMG]
     

  15. SmallSpaceBigImagination
    Joined: Mar 2021
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    SmallSpaceBigImagination Junior Member

    Looking for costal sailing, not looking to do a crossing. But I've read that cats over 44' offer smoother rides... I'm just not willing to push that many joints on the design. So I'm thinking 35 - 40 feet.
     
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