Internal walls question

Discussion in 'Wooden Boat Building and Restoration' started by milo12, Aug 28, 2015.

  1. milo12
    Joined: Nov 2013
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    Location: CA

    milo12 Junior Member

    I am looking for examples of how wood internal walls are built. All my books cover the hull contruction but no mention of internal structure, other than bulkheads. I want cabins and heads etc separated by real walls. I would like walls that feel solid and secure, like you would expect in a house. Is something like a house wall ok? For example 2x2 framework, insulation, with 1/4 ply both sides?
  2. Deering
    Joined: Feb 2005
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    Deering Senior Member

    Not quite sure what your goal or application is, so difficult to answer. Are you trying to insulate? Reduce noise?

    You're in CA. How about tongue & groove redwood? Strong and rot-resistant. Find a small mill and they'd be happy to mill up whatever dimension you're looking for.
  3. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    You are correct, use 2 x 2 stock ( 1.5" x 1.5" ) FOR BOTTOM AND TOP PLATES, studs, plus ply each side. In the bath I will use a 3 side shower unit with a toilet mounted inside the shower pan.drill an extra drain and a curtain to cover the inside of door.
    forget redwood. PS use screws not nails.
  4. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    It has been done often for structural reasons, basically it's a sandwich. The weight can be excessive if you're not careful, and on some designs the excessive rigidity of the bulkhead or the division can create hard points on the hull and problems with the hull skins.
    As the divisions seem not be structural, you'll be surprised of the rigidity of 1/8 plywood skins over a 1 inch foam or honeycomb, that gives a 1.5" total thickness panel and it's enormous on a boat. Doors in a house have just, or less than that thickness... It's not precisely light also and cheap.
    Make an excel sheet, take in account the weight of the glues, fillings and other, plus plywoods etc... you'll be badly surprised in terms of weight, price and work in comparison of a 1/2" plywood rigidified with some decorative pieces of wood. The good ole principle MISS.
    1/4 plywood is far too much, the sum of the 2 skins is already 1/2". You're exploding the weights.
    In my opinion, it's better to use a polyethylene honeycomb which give a very resilient panel, is light around 60 to 80 kg m3, doesn't rot, and very easy to glue with a simple vacuum cleaner as vacuum pump.
    Over 1" of honeycomb you're wasting money, material and adding useless weight.
    Forget the polystyrene foams that absorb water and become nuisances. Most polyurethane foams are foamed with CO2, a very hydrophilic gas, you need a foam made with inert gas as nitrogen and that's expensive and hard to find.
    Most open cell foams for hulls need too much filling and that's very heavy.
    The closed cells foams are very expensive and sold only by big boxes.
    To give you an idea a lot of plane floors are made with 1/2" balsa core and 2 skins of 0.4 mm to 0.6 mm aluminum and it's very rigid...
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I agree with Ilan, in that you don't want to apply typical housing construction techniques to your boat. Land based structures are typical way too heavy and developed for static loading, while a boat requires lighter, often more flexible structures that can cope with dynamic loading.

    Plywood (alone) is the usual choice if the boat can tolerate the weight. Composite (of some sort) is the call if weight has to be more closely managed.

    It would be easier to be more specific if you provided a little more information, such as year, make and model of the boat, plus any drawings or pictures of your intentions. A set of actual goals would also be helpful, as well as the planned use you envision for her.
  6. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    Thanks PAR, often I feel we are the guardians of the holy temple of the forum keeping the good practise in boatbuilding.
    As you and I have said hundreds of times, it's better to stick to the plans of the NA, as often the divisions are structural items (and lots of furniture also) with a studied flexibility for dynamic loads and the poor NA spent hours to get the cheapest, lightest for the price and convenient solution. To modify you need to know where you're going because you are going to enter in a spiral...a boat is conceived as a whole, not an assembly of random bits and parts.
    I'm pretty sure that the person asking the question does not see, and it's normal, the engineering, cost and amount of work needed by such trivial goals as "feel like house walls". It seems so easy at first sight...

  7. milo12
    Joined: Nov 2013
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    milo12 Junior Member

    Thank you for the excellent advice. I like the idea of a light PP core wall, light weight and quiet. Lots more I need to look into.
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