40 ft cruising cat design. First steps.

Discussion in 'Multihulls' started by bscatam, Mar 28, 2016.

  1. UpOnStands
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    UpOnStands Senior Member

    lightweight

    lightweight but practical furniture - sounds like just what a lot of builders need.
    expensive? strictly one-off?
     
  2. bscatam
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    bscatam Junior Member

    Not so expensive. According to my calculations 1 sq.m. will be around 1 -1,1 kg for 18 mm thick panel. But I am in Europe.
     

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  3. catsketcher
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    catsketcher Senior Member

    Gday Bscatam

    I have used a product called Featherlight in some of my boatbuilding (along with Duflex) These are cored panels from ATL. The Featherlight is somewhat like what you have but with a glass laminate instead of the timber your panels have.

    Featherlight is nice stuff, stiff and strong enough for most interior uses but it is a real time black hole when dealing with its edges. I have to rout or dig out the core to a depth of about 10mm and then cove in a nice rounded edge of epoxy bullnose fillet. I can't ever get it done in one go. If I make the epoxy thick enough for a one time pass then I get little voids in the mix. A fair bit of sanding and filling is involved. In the end I am happy with the result but there is a lot of effort required.

    If you can get a really strong and watertight edging that would be great BUT I would urge caution and the making of lots of small test pieces. I would not like to have the Featherlight have any exposed edges inside a boat - it could turn to mush with long term exposure.

    I would also urge caution about using the Lagoon style interior fitout for a light cat. In the small amount of time I have spent on condo cats - a Lipari - I was surprised to see that the furniture is not integral to the hull structure. Of course the hull laminate is beefed up accordingly but I couldn't get my head around the fact that the cupboards were not used as part of the hull stiffening. If you put your keys on top of the cupboard they could fall down between the cupboard and the hull. It seems a waste of all that amazing stiffness but it probably saves hundreds of ours of fitout.

    I can get the idea that you could CNC the furniture in a day but I would think it would take a few weeks/months to install. Coves, even where the interior panels meet, are a bugger.

    cheers

    Phil
     
  4. groper
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    groper Senior Member

    Well assuming you use okume or similar density timber for the plywood, I have 1.68kg per sqm just in the wood. Add the glue and the veneers and the honeycomb on top of that, I'd say your about double your calculations...
     
  5. DennisRB
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    DennisRB Senior Member

    How about XPS as a core? At least is waterproof...
     
  6. Gus7119
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    Gus7119 Senior Member

    Love it. Its come a long way from the humble beginnings. You'll always have diffrences in peoples likes and dislikes az long as it make you happy, I myself like it. Can see a lagoon influence slightly. But they sell alot of boats ao must do somethings right.
    As for the raked windows I did a while ago see a wid tunnel video at a boat shead with raked and verticle but the difference from memory was not worth discussing. The diffrence came when they lowered the coach house and made some alterations to the hull shape. But your never gonna get rid of it and unless its a race boat or speed is the goal as long as it comfortable and gives you satisfaction you should be proud as it will by the looks be a lovely boat.
    The only question I have is the coach house roof. As gropper mentioned earlier a flat to to stiffen can be difficult, add a little curve and its much easier. Would love to know your solution for this, is it maybe a central post or materials?
    Regardless just a fantastic effort. Now for the painful bit. The Dam build. Hope your able to get it done quickly unlike the many who start and 10 years latter have a blank empty hull sitting in a paddock roting.
    Best of luck.
     
  7. bscatam
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    bscatam Junior Member

    Thanks Gus. Coach ruff actualy has a slight curve it is not flat.
     

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  8. bscatam
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    bscatam Junior Member

    Yes. It's possible. But not shure about thin ply. You need special glue. Chek with SIP pannels for prefabricated houses which type they use.
     
  9. bscatam
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    bscatam Junior Member

    Fast cat.

    Just playing around fast cat. 45 ft profile.
     

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  10. DennisRB
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    DennisRB Senior Member

    I think even with a slight angle, like in your second post, the aesthetics will be much improved with no real downside. You had it right the first time. At the bare minimum you will get less comments about it being a lagoon. :)

    Nice fast cat. Can you shave much more freeboard from the hulls and still have head room? Rudders look small. Edit, I just zoomed and saw the head room measurements, not really. As for this roofline, I think a higher profile at the front would have no real downside on performance but a lot of benefits inside :p A shallow rake does look fast though.
     
  11. bscatam
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    bscatam Junior Member

    Fast cat.

    And some fast sections to fast cat
    profile ;)
     

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  12. waikikin
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    waikikin Senior Member

    Those more vertical sides probably put a hand rail in easy reach. One of the styling things I've seen on the sloped cabins is louvres that act as steps, pretty sure Leopard has them on the front, only remember seeing them on the side on a Hitch 40 a lot of years ago, maybe you could have steps up the sides with glazing to the risor section... might be the next big thing in cabin styling;)
    Jeff.
     
  13. bscatam
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    bscatam Junior Member

    Testing lines. This is a huge advantage of 3D CAD software. You can virtually correct all mistakes in lines and surfaces.
     

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  14. bscatam
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    bscatam Junior Member

    Fast cat. Not racked windows

    Playing with lines. Racked :D
     

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  15. waikikin
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    waikikin Senior Member

    Are the missing topsides a developed surface for sheet materials... Starting to look "Spirited".

    Jeff.
     
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