heavy cargo sailing cat

Discussion in 'Multihulls' started by JK_Millwright, Oct 28, 2015.

  1. JK_Millwright
    Joined: Oct 2015
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    Location: Southwest Florida

    JK_Millwright Master Carpenter

    I'm looking for cruising cat designs which can safely carry extremely heavy cargo.

    I am a professional woodworker, and intend to take a scaled down but highly capable shop with me so I can work as we travel. bare minimum 4000lbs machinery & tools, but 5-6000lbs is more likely.

    need to carry a 4x4 mini truck (kei truck) or John Deere Gator/Kubita buggy + fold-up utility trailer

    I also need 3-5000lbs cargo capacity for transporting & trading exotic hardwood lumber

    my wife is an avid gardener, and must have at least a mini garden/greenhouse for her orhids, tomatoes, ferns & other greenery. Im guessing a 1500-2000lbs allowance would keep her contentment level high

    Ill need a 2-3ton crane for moving machinery/buggy around (machines on deck for work, -& down low into holds when underway)
    and of course we'll need a tender/dinghy, so another 3-500lbs there

    then of course theres the usual acoutrememts for wife & I + our son (likely a teen by the time we're in the water) and sometimes a parent or an older son
    3 fulltime residents plus 1-2 fairly regular guests. I can only guess a few to several thousand lbs more weight???

    We want a Catamaran for their inherent safety, stability, multiple large & open spaces (living & workspaces). unsinkability, shallow draft, and because we just like them!
    Seaworthyness is of course the #1 priority, and our definition of "Seaworthy" includes surviving collision with floating logs, uprooted trees & partially submeeged shipping containers.
    unfortunately I am finding that steel is not a possible material choice; but has or does anyone use or contemplate using steel plating on the bows & contact areas of hulls? perhaps a composite (vacuum infusion) hull with metal armor plating on or in the laminate stack? or How about the same for cold mold wood-epoxy hulls. armor-plating where it counts most? (think "steel toe/shank boots!)
    colliding with a floating shipping container is probably our greatest fear when it comes to passagemaking/ocean cruising.

    All the catamaran designs I've found are exploiting sleek design & lightweight construction to maximize speed & efficiency. -for simply a cruising cat, many of the designs would more that serve us well , but what we NEED is a large, strong cat design; which can safely carry quite a few tons payload!
    it's a good thing that SPEED isnt too high on our priorities, but as for even finding a design that looks like a possibility; I'm just not sure enough as to what we need, in order to buy any study plans yet.

    I should add that the power needed for my machinery requires a fairly large genset, and we want to use that genset to power electric propulsion motors in each hull, coupled to Hamilton or Berkely jet drives (shallowest draft, simple, lightweight, & they provide the least risks to marine life, which is extremely important to us)
    the bigass genset will be alot of weight, but we'll reduce weight with electric propulsion & jet drives. I find 50-100kw genny's in the 2500-4000lbs range, while a pair of 25-30kw motors are only a couple hundres lbs. we'll keep genset weight as low as possible with the intent of allowing for a smaller secondary genset (7.5 - 10kw) the lightest battery bank as becomes reasonably available in the next several years.

    We're presently building a mini diesel-electric system on our Shop Barge using a 15kw genset, forklift charger, 8d batteries and 36v high torque golf cart motors, ths should be an excellent "proof of concept ". and experiment prior to making larger commitments.

    We've been considering ordering study plans for the Bruce Roberts Contemporary Cat 785 (downsized if possible?); his 20m Euro Cat 2000. and his MS65 Catamaran, but I dont even know if I'm in the right ballpark with any of these as far as capacity and cost of materials are concerned.

    perhaps a cat with big w-i-d-e highly bouyant hulls is what I need to find!?

    I hope Ive conveyed enough info as to our needs, Im hoping to find out or at least get some advice & opinions on:
    A. How big of a cat will we actually need for such capabilities?
    B. Are there any designs out there which might be suitable for our heavy cargo needs?
    c. What might be the best materials and construction method for a craft like this (with of course, my skills and equipment utilized to their fullest potential?)
  2. Corley
    Joined: Oct 2009
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    Location: Melbourne, Australia

    Corley epoxy coated

  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    There is no thing as "unsinkability", particularly on a heavily loaded vessel. Also, catamarans are a bad choice for heavy loads. They will have a very large draft compared t a monohull.
  4. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    From what youve described - a 65ft cat is not even in the ballpark. You will likely need something like 90ft and the budget to build something like this will run into several million dollars. So unless you have some very deep pockets, this is just another pipe dream.... and heavy sailing cats, dont sail very well at all, it will be a motor sailer at best, and likely simply just a motor cat most of the time depending on how much windage the design requires - which sounds huge by your list of requirements...
  5. JK_Millwright
    Joined: Oct 2015
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    Location: Southwest Florida

    JK_Millwright Master Carpenter

    thanks for the nod to Kurt Hughes, he has a few designs that appear to be possibilities, and I particularly like his design philosophies

    I thought I had written unsinkability as "unsinkability ". as in far less likely than monohulls (to leave one stranded ; than a monohull which makes a career change to a submarine with 1-way ticket to The Jones Marina & Subsea Boatyard
  6. Richard Woods
    Joined: Jun 2006
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    Location: Back full time in the UK

    Richard Woods Woods Designs

    Years ago I drew a 70ft catamaran that would meet your requirements. It was designed as a survey/environmental research boat in the Indian Ocean. It had living space for 22 scientists, a big lecture room, a microlight and mini sub etc. So it could take the weight you need.

    Where do you plan to work? presumably only in the US, as you will find it hard to get real work abroad without work permits etc (no one likes illegal workers!)

    So why the need to take all that gear with you?

    Richard Woods of Woods Designs

  7. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    It would probably be easier and cheaper to outfit two 40' containers and have them shipped around to meet you from place to place than try to carry them with you.
  8. redreuben
    Joined: Jan 2009
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    Location: South Lake Western Australia

    redreuben redreuben

    I think without an extraordinary amount of money a catamaran is the wrong kind of boat for you. I would be looking at maybe converting a fishing boat or other commercial vessel of some sort, I mean, gardens, a crane and a bobcat, not realistic.
  9. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    With such variability in loading, the underbelly will need a lot of clearance to avoid slamming. The height of the upperworks will rise accordingly. Not really going to function that well as a sail boat.
  10. whitepointer23

    whitepointer23 Previous Member

    I think he needs to rethink the whole plan and come up with something realistic. How the hell will 50 hp electric motors drive a Hamilton jet let alone an overweight cat . I would say get some boating experience 1st. Unless the thread is a joke . Its not april 1st is it.
  11. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    If this thread is not a joke then you should read the book on the catamaran Linase. It is written by a man called Thompson. He built it after work and wrote a book that is on Kindle. It was steel, was huge and had an amazing variation of sails for its rig. It even had hydraulic legs that could push it out of the water and onto the sand.

    If he is still around he could guide you. Most (all?) on this forum are of the "light is good" persuasion and would think that the idea is pretty crazy. The cost of the rig would be more than my whole cruising cat is worth - and I cruised with 4 on board comfortably.

    That is the biggest worry with size - the loads. Some loads go up in a proportional fashion but others go up by the square or the cube. As stability goes up by the power of 4 the rig needs to be hugely strong to cope. I think a rigger would run away from this style of boat as you would not know what the limit loads are. I don't like buying stays for a 38 footer. The cost of one stay for a 70 footer this heavy and stable would be tremendous.

    Cheaper to fly home and work from your shed and go in a modest cat


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  12. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    It is a massive project, regardless of whether it turns out to be lemon or otherwise.
  13. jamez
    Joined: Feb 2007
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    jamez Senior Member

  14. Mr Efficiency
    Joined: Oct 2010
    Posts: 10,390
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    Location: Australia

    Mr Efficiency Senior Member

  15. whitepointer23

    whitepointer23 Previous Member

    I know the walking cat well. He built it round the corner from my aunt in inverloch when i was a kid. It was at lakes entrance at one stage on display . Pretty cool the way it pushed itself up the beach. Last time i saw it was early 90's in a paddock . It was a big boat. I remember them parking their cars in the tunnel when it was in his yard. Do you know where it is now phil.
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