Affordable 9m Catamaran

Discussion in 'Multihulls' started by Xpert, Jun 23, 2020.

  1. Xpert
    Joined: Jun 2020
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    Xpert Junior Member

    True, very true, at the moment i'm just experimenting with the hull and running the simulations.
    Draft is at 0.7m and air gap 0.35m so added wavesplitter underneath (image attached)
    Experimenting with different bow and aft and ruining simulations for performance improvement (attached)

    The height of the catamaran from WL to the top of superstructure so far looks like 2.5m (or from floor /main deck/ to top 2m)
     

    Attached Files:

  2. TANSL
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    TANSL Senior Member

    Air gap 0.35m could be too low a figure, unacceptable, although it naturally depends on the design category of the boat.
    In my opinion, the shapes you have at the moment, the tunnel, the wet deck, seem unnecessarily complicated. Try to create shapes appropriate to the ship's SOR and don't limit yourself to just what you can do with the rendering software. Why such a deep "V"?
     
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  3. Xpert
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    Xpert Junior Member

    Yes, cat is intended for coastal cruising
    The "V"shape hull allow to grip the water when beating the windward.
     
  4. Richard Woods
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    Richard Woods Woods Designs

    The sensible thing to do is buy a used Catalac, sail it for a season and then you'll know what changes to make. Or maybe you have already done that? I agree with Tansl, leave the pretty pictures for now. Design the boat first. Then draw it. Then do the pretty pictures.

    Richard Woods
     
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  5. Xpert
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    Xpert Junior Member

    Don't really understand what you mean by pretty pictures? as i use the DELFTShip and MAXSURF.
    What you mean design the boat? do you you mean to start from interior? then adopt the hull to fit the interior?
    Draw it? i have all the drawings (form plans if you mean) of all the models so far.
     
  6. fallguy
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    fallguy Senior Member

    I was going to build a solid foredeck on my boat and was warned against it by many for slamming potential in any steep stuff. I was gonna setup a place to hit golf balls. Going with a net or mesh now. Just fyi.

    I think Woods might prefer you talk about the performance goals and hydrostatics more. Just guessing here..

    Also, not sure I understand the reasoning behind carbon. Expensive and generally a failure point in the layup, no? I doubt you can produce an affordable boat with carbon.
     
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  7. Xpert
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    Xpert Junior Member

    Well for me personally the benefits of carbon fiber are:

    1. Weight - it is better to have a 3 tonne boat vs a 4 tonnes - as on the water it really matters.
    2. Strength - with same amount of material yo achieve stronger results in fact when combined with the right epoxy, is stronger than many metals.
    3. Expansion - don’t expand or shrink as much as fiberglass when the temperature changes.
    4. Workability - not so itchy

    Cons:

    1. Price - Carbon fiber is at least 5 times more expensive that the fiber glass at the moment in UK at least
    2. A 100m2 hull with 5 layers, just cloth, will cost = 10k in Crabon and 2k in fiberglass
     
  8. bajansailor
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    bajansailor Marine Surveyor

    Xpert, if I may use a car analogy - what you are proposing re revamping the old Catalac is similar to putting the Morris Minor back into production but with a carbon fibre body instead of a steel body that is prone to rusting out.
    And this modern day Minor will cost twice as much as a modern day Mini....... and even if it was the same cost, 99% of potential car buyers would probably choose the Mini over the Morris Minor.
    In similar fashion, 99% of cat buyers would probably choose (for example) a new Woods Sagitta over a new Catalac if they were given the choice.
     
  9. fallguy
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    fallguy Senior Member

    So carbon and epoxy and core are gonna cost you, the manufacturer, $35,000. You don't even have the boat made. How are you going to keep the boat affordable?

    And you still haven't addressed carbon's elongation issues. Aren't most people building carbon hybrids for this reason? I am asking; no snark intended.
     
  10. Xpert
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    Xpert Junior Member

    No, i proposed to take an old successful model (500 units produced) as a base of sizes, dimensions, layout etc... not to copy/paste it in modern material,
    but modernize it, hull performance (hydrodynamics), propulsion, solar, design interior/exterior, etc..

    A better option will be CatNano, Wildness 1030, Arrow 1200, Gforce 1200 (latest 2 two are slightly bigger)
     
  11. Xpert
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    Xpert Junior Member

    25k ~ 35k for a NEW full laminated carbon catamaran hull is not so mach at all.
    Elongation - the issue is the core not carbon, that's why we go with honey comb, id dose not expand longitudinal, due to it's hex structure.
     
  12. Richard Woods
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    Richard Woods Woods Designs

    Like myself, Ad Hoc, Bajansailor and Tansl are full time, fully trained professional designers. Dan is a very experienced boater and home builder.

    We know the last thing you will finalise is the lines plan. For you cannot do that until, for example, you have a detailed weight estimate and CofG position. You cannot move or lighten the ballast keel to correct errors on a multihull. So thats part of what we would call designing as opposed to drawing. When I started designing a self propelling pencil was the latest high tech device. But successful boats were still drawn. A computer is only a tool. Mozart wrote great music without needing a 16track studio to work in.

    I assume you have done a costing, so will know that the plug will cost you more than a one-off boat, as it has to be perfect. And that moulds will cost twice the hull shell cost, as they have to be much thicker and be heavily reinforced. So I'd guess you will spend 200,000 before you even start to build the first boat. And then you can only spread that cost over 100 mouldings max, after that you will probably need new moulds. So add 20,000 to the cost of each boat.

    There is a reason why boats are so expensive!

    Richard Woods
     
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  13. Xpert
    Joined: Jun 2020
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    Xpert Junior Member

    Well... thank you for the introduction
    Yes, noted.
    Yes, I'm familiar with moulds and plug costing (we've budget 100k) insignificant cost per 100 moldings 1k

    PS: You forgot the boat design cost which will be from 25k~50k
     
  14. fallguy
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    fallguy Senior Member

    check your math my friend..I will delete hence
     

  15. Rumars
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    Rumars Senior Member

    This is the real elephant in the room. The technicalities of design and building can all be solved, but can you sell it for a profit? The problem is that it takes exactly the same time to wire a light regardless of how big the boat is. A bigger boat needs a longer wire run and a longer LED strip, but those are insignificant costs compared to the electricians hourly wages. This applies to the entire build, man hours are the big costs not the materials. Unfortunately today we can not skimp on fitout to save money. In a comfortable cruising boat the customer expects a toilet with holding tank, shower with hot water, gas range, full electronics suite, and a USB charghing port next to every pillow. But, even with all this features there is only so much you can charge before you price yourself out of the market.
    I find starting the design with a high man hour building technique like carbon honeycomb is a problematic approach for a small, non racing boat.
     
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