Open Source Design 20M Cat

Discussion in 'Multihulls' started by truecougarblue, Dec 26, 2012.

  1. truecougarblue
    Joined: Dec 2011
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    truecougarblue Junior Member

    I have 3 years before I will be ready to start building my boat. I hope to have this thread start the process of design. I have not yet decided on purchased plans vs. own design but as the thread title suggests I would like to see the design process laid out in this open forum so that I can benefit from the experience of others and that others can in the end benefit from my work on the project.

    The boat planned (in the most preliminary fashion) is a 20M biplane cat. The primary quality in the boat is that it be comfortable to live aboard. Secondary is tame sailing characteristics, and third is a capacity to cruise up to and including ocean crossing.

    I am very open to guidance and discussion on beam, draft, freeboard, bridge deck clearance, etc. My current thought on material for the hull is aluminum.

    I recently visited a 50' ferro project for sale, the owner had died before it was completed. I don't want this to happen to me. I want to design it, build it AND sail it. To this end I am thinking about feasibilty on a very simplified build before launch with hulls, basic bridge beam, and rigging. I will abandon this concept if it is silly, but it seems a good way to go on at this point.

    I'd love questions and advice. Hopefully I'll be able to keep updated summaries posted of current specs and scantlings as they are developed. With 3 years to go before the build begins the one thing I'd prefer not to see is a comment that I should not make the attempt, or that I should buy rather than build, or that I should first engage a designer.

    Fair winds and good sailing to all in the new year.
     
  2. Richard Woods
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    Richard Woods Woods Designs

    A 20m catamaran is a VERY big boat and by implication very expensive and time consuming to build (in any material)

    How many will be on board full time (excluding occasional guests)?

    What is your budget? more than USD500,000 or less? if less don't consider a 20m boat. Remember that once in the water running costs tend to average 10% of build cost, big boats are expensive to cruise and you need money for maintenance

    Once on the water fitting out will be very much harder to do than when in the shed. Also in general the furniture on a multihull helps stiffen the structure so an empty boat won't be safe to take to sea

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  3. masalai
    Joined: Oct 2007
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    masalai masalai

    Is this another thread of the style "build a boat and do a lap" - He built and got 20 miles before it broke up after passing the Golden Gate - entertainment for many for a while... and great concern for the coastguard and significant cost for the rescuers...

    Hi Richard - my guess nearer a million if built to reasonable standards and quality...
     
  4. truecougarblue
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    truecougarblue Junior Member

    I'm comfortable with 500-800K.

    If the fit out afloat isn't tenable it won't be the path taken, but I do need to look at it.

    Live aboard will be 2 normally, 5-10 frequently, and up to 16-20 ocassionally.
     
  5. Richard Woods
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    Richard Woods Woods Designs

    That's a serious project.

    I would strongly suggest getting some professional advice early on. If nothing else it will save you a lot of time. You can read up about law and then defend yourself in court, or perform DIY surgery, or deal with the IRS yourself. But I suspect you don't, you get a professional to help you

    I'd also suggest you contact Richard Spindler of Latitude 38 and go out on his Hughes 63 Profligate. He often takes large numbers of people sailing (there were 11 on board when I raced it). But even so he told me he had too big a boat. And he and his partner are very experienced sailors.

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  6. groper
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    groper Senior Member

    id like to see an open source design progress to see what becomes of it, although its kind of asking the impossible as every design needs to consider - hows its going to be built, with what materials and appropriate skills are available, its intended usage, and a whole lot more, so it actually ends up a very specific.

    Who will be physically building it, a professional yard or you by yourself or with help from your wife or paid help from others? What skills are at hand?

    Why aluminum? Have you considered other materials?

    So you want to have berths for 20 people? So is that 10 double berths; or 6 single and 7 doubles; or ????

    What level of fitout are we talking... ie is this a fully airconditioned, energy hungry boat with large gensets running fulltime and the running costs that go with it, or an eco friendly, energy efficient boat?

    What kind of performance under sail do you want, or will you be motor sailing most of the time?

    Soo many variables.... nobody can offer anything of real substance until you define a realistic "statement of requirements" which is what a professional designer would ask from you for anyway...
     
  7. truecougarblue
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    truecougarblue Junior Member

    I think 5 doubles with the assumption that if the 20 number were approached it would be in fair weather and safe harbor and additional sleeping arrangements could be provided on deck.

    I would like to build as much as I can but I will contract out what I can't do.

    Aluminum after considering other materials due to a combination of factors; size of the craft, low maintenance, durability, to name a few. I'm not married to AL but it seems to have clear advantages over GRP, steel, or wood for a owner/builder cat this size. Feel free to try to convince me otherwise.

    I lean toward energy friendly and efficient, I will need to make a list of expected loads I guess as one of my first steps.

    The performance is a secondary or even tertiary requirement, I will accept what the design gives. At 20M it should run pretty fast unless I really screw up. I would expect it to sail on cruises, if any. I believe most motorsailers are overpowered so I'm thinking around 5hp/ton as a starting point.

    Thanks for the questions.
     
  8. masalai
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    masalai masalai

    Hi truecougarblue,
    Low maintenance in relation or in comparison with what? (doing no maintenance at all)? All ships have similar maintenance requirements just that BIGGER costs BIGGER BUCKS exponentially...

    All materials have their needs and issues specific to that material when considering durability, "minimal"-maintenance, build-methodology, a demand for a commercial slip/hard stand for maintenance, capacity to beach and scrub the bottom regularly, change the engine oils and coolant, polish the fuel, maintain the standing rigging, running rigging, electrical and electronic systems...

    You have a HECK - OF - A - LOT of things to consider before you put pen (or pencil) to paper for the design of your boat - (beyond the lady setting out layout and furnishings and kitchen needs)...

    DO A DETAILED (statement of requirements) SoR first, including costing for ALL the components to make the domestic (living space) comfortable, complete and satisfactory to your partner - then consider your realistic options like: - - size, - engines, - ships electrical power needs, - Water maker, - fuel storage, - water tankage and why, - RO watermaker is best if run daily else it must be 'pickeled' and set for storage mode - - navigation, - communications and safety systems - - Mast and sail systems. ALL have significant costs and demands...

    Will you keep it at a marina, can you afford That cost? - - - Have you assessed the market to deliver those "visitors" regularly?

    Are you considering charging your 20 or so guests, do you have the necessary licences and capacity to get insurance (usually in the vicinity of US$10 to 100 million public liability cover) and insure your boat as well.... You may also need a commercial survey certification on the boat as well before you can consider any form of 'commercial operation'...
     
  9. tz3dcom
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    tz3dcom 3D

    Hi truecougarblue,

    If you want to develop a new innovatory cat. I would suggest that you can find a senior designer or cat expert like Richard Woods or Gregor Tarjan to get the constructive views during the design process to guide a good cad designer to push the design step by step well and quickly progress .

    A 20M cat design is a extremely complicated project . I'm impressed with the process . it's long time story maybe need take years. However if you have the good professional team help , you can save the work time in process . it's possible to start from the design to sailing within 2.5 -3 years.

    As I know Gregor Tarjan started the Alpha 42' project design from beginning of this year. until today the hull mold almost done. it's a great innovatory design , They sold the 6th Alpha 42 before Christmas .I expect have a chance sailing Alpha 42 with Gregor one day.. maybe the end of next year ?

    By the way my personal view that is hard to building a 20M cat with a good design , good quality , good material within 500-800K budget. You may thinking the question of keep and create the wealth for your huge investment . Can we imagine a VPLP design cat with all carbon if it will be sailing well still and worth collecting like ART of Picasso after 100 years ?
     
  10. cavalier mk2
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    cavalier mk2 Senior Member

    Look up Barry Choy of Choy Design. He has plenty of experience in aluminum and larger sizes.
     
  11. Tad
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    Tad Boat Designer

    Bob Harris designed the 63' aluminum cat Sea Jewell and she was launched in Vancouver in 1974. Beam is 27'3", displacement 55,000 pounds, and sail area 1750 sq. ft. in a ketch rig.

    So you have 50,000 pounds of boat to build, materials will be at least $10.00 a pound, so $500k in materials. Man hours will be at least 20,000, at $40Hr labour will be $800k......total ballpark will be $1.3m without taxes and overhead......
     
  12. truecougarblue
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    truecougarblue Junior Member

    Should I rename the thread 15M cat?
     
  13. jamez
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    jamez Senior Member

  14. Mr Efficiency
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    Mr Efficiency Senior Member

    That cuts it ($) in half at least, I'd say.
     

  15. truecougarblue
    Joined: Dec 2011
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    truecougarblue Junior Member

    Thanks for the link, I like this plan.
     
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