heavy cargo sailing cat

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

  1. waikikin
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    waikikin Senior Member

    It sounds awesome, like a giant turtle. Some pics would be great.

    I think if JK-Milwright is serious about carrying some load that a big scow might be the go http://www.boatdesign.net/forums/sailboats/new-zealand-scow-28735.html


    Jeff
     
  2. waikikin
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    waikikin Senior Member

  3. whitepointer23

    whitepointer23 Previous Member

    I just googled llinase catamaran and found the utube video too. Its amazing how he built those hulls on his own.
     
  4. waikikin
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    waikikin Senior Member

    A great effort.. to keep up the passion for 9 years or so, raise family, launch & enjoy. A terrific role model for " Having a go".

    Think, from the philosophy that some of these attributes are being overtaken or maybe just the tools have changed. A great story:)

    Jeff.
     
  5. waikikin
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    waikikin Senior Member

    BTW Phil,

    Thanks for the info, pretty cool story.

    Jeff.
     
  6. CT249
    Joined: May 2003
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    CT249 Senior Member

    Llinase was a great achievement, but it wasn't built like something that a professional woodworker like the OP would want to show to clients. Inside she had normal house furniture. Her owner/builder told me that the secret to finishing such a massive boat was to look at every piece as a project in itself, rather than just one piece of an intimidating project.

    I did ask him why he built such a big boat, and his reply was that his wife wanted a really big boat. "No I didn't" was her very quick response!
     
  7. whitepointer23

    whitepointer23 Previous Member

    Do you know what became of it.
     
  8. whitepointer23

    whitepointer23 Previous Member

    I don't think llinase would even be large enough for the op, s requirements.
     
  9. JK_Millwright
    Joined: Oct 2015
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    Location: Southwest Florida

    JK_Millwright Master Carpenter

    thats just about perfect, thank you!


    some of this is easily downsized or otherwise reduced.
    my tools + equip, & (timber) cargo, probably not so much... On the water before I turn 50 means I continue working, and thats a minimum "kit" for what I do. Timber cargo for use & for small scale trade -same thing...

    most others can be cut down, once I have figures to begin with, hence the reason for my post here: feedback & advice/opinions from folks who know about this stuff.

    What Im gathering is: Id need a 75'+ to haul everything Id like to have (which is probably too far beyond what I could take on). but the "right" 60ft and reducing /eliminating whats not absolute necessity, and I can meet my goals


    As for the possibility of using jet-drives, I am presently using Yamaha waverunner jet drives, driven be 36v performance golfcart motors, powered via forklift charger/8d battery bank and this is fed by a 15kw/Cummins. the torque is very linear throughout the rpm range, and on a pontoon work-barge, it moves quite well. twin 25 or 30kw electric drives are sufficient for powering a 60ft cruising cat, and if I can get it to work with larger jet drives instead of CPP, it would be my preference, as theres no churning prop to chew on marine life.
    We'd gladly accept a performance/efficiency disadvantage, if it protected & safeguarded the lives in the environment we're visiting.

    I'd like to express my appreciation for all the helpful links, now I'm getting a rough idea of what vessels can carry, and what's realistic (& whats not)
    thanks so much!
     
  10. whitepointer23

    whitepointer23 Previous Member

    Red rubens fishing boat idea makes sense. Economically and for load carrying ability
     
  11. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    Don't go jets

    There is some physics behind the choice of drive. Heavy slow boats - and this means all of us with our multis - need a strong push. The best way to push such a load is with a large prop.

    In the world of boat physics there is a tangle between the linearity of Newton's third law (Equal and opposite reaction), his second law (F=ma) and the exponential requirement of kinetic energy KE = 1/2mv^2.

    What this means is you have to push water out the back to go forward. If you push it twice as fast backwards then you will get twice the force with the same mass of water. BUT to push it twice as fast you need 4 times the energy.

    So you want to push the water as slowly as you can for efficiency. Hence big props. (Bigger mass rather than acceleration) You also like big props to start and stop quickly and whenever there is wind. Jets have been tried on multis since Hamilton made the first one but they did not work well. (Lock Crowther had one on one of the first Kraken 40s but it was no good in any wind. (In one of my AYRS books)

    I have never hurt any sea life with my outboard apart from a jelly fish in thousands of miles and can't see how you could with a slow boat (8 knots). It is the fast runabouts and tinnies that hit turtles and such. Turtles do get struck by props and they can get taken by surprise by a kayak but I have never suprised one motoring in the cat. As for dolphins - these guys are way too smart and fast for us to hassle them - they get near when they want to.

    In the bay in Brisbane the ferries that ply the islands at 20knots DO have to use jets. They were made to change over in the last few years. The reason is because they share the water with dugongs. Fuel consumption has gone up but the dugongs are safer which is good. I have never gone fast enough under power to worry even a slow dugong. If you go 20 knots then that is a different issue.

    cheers

    Phil
     
  12. Skip JayR
    Joined: Sep 2015
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    Skip JayR Tri Enthusiast

    JK_Millwright, I suggest you contact Kurt Hughes... he is the right designer for you for such a project.

    He designed different multihulls, not just for cruising, but same for commercially use...
    http://www.multihulldesigns.com/ferrys.htm

    ... beside bigger cruising cats
    http://www.multihulldesigns.com/cruiser.html

    Kurt is open into different directions, so he can give you some orientation with good advice.

    You can contact him easily via Facebook, too...
    https://www.facebook.com/kurt.hughes.54

    Send him my warm greetings... Good luck !
     
  13. JK_Millwright
    Joined: Oct 2015
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    Location: Southwest Florida

    JK_Millwright Master Carpenter

    For plans that actually have the weights (vessel vs max loaded) I'm taking the "vessel weight" to mean a normally built-out & complete boat... I suppose all the joinery & interrior fit-out could be built lightweight (but still strong & aesthetically pleasing... such as wood veneer on composites. and light but strong hardwood for eg. 5/8" Poplar Mortise & tenoned, is about half the weight 7/8" cope & stick Beech or Walnut, and tremendously stronger (M& T is still King of joints)
    Im wondering how much weight savings could be gained in the interior work?
    and before someone says "Ewww! POPLAR! thats ugly-ness incarnate!". -That all depends who's in the finish shop, & I can make poplar look like just about anything, not to mention it takes a great pigmented finish.

    As for fishing boats or monohulls, I'm liking the looks of this design:
    http://www.bruce-roberts.com/public/HTML/descriptions/trader65_description.htm

    steel hull reduces our worries of holing /sinking, and Im perceiving this would require alot less cost than a roughly equivalent sized cat???

    when looking at Ballast, can my equipment be used as ballast, or does this simply need lead in its keel. The biggest thing Id miss, is my WideBelt sander (about 4000lbs,) but to run, it requires massive dust collection and a fairly large compressor). compressor and dust could be fixed items at bottom of hull, machinery has to be moved around.
    how much of the ballast spec is req'd to keep a vessel stable (or is this not something to mess with?)

    I'm also wondering what size of electric motor would be appropriate for something like this, as my electric motor experiments have been with our tritoon Foodboat and fiberglass (22ft Avenrura) pontoons....
    pontoons are much like cats in that they're pretty easy to move through the water. where as a monihull like this which drafts 6ft, seems like it would require alot more enertto push hull with any authority????
    I'm the best at designing & building cabinets, stairs & built-ins, but when it comes to boats, I'm not so sure if my perceptions are in the right direction, so I appreciate all the helpful advice
     
  14. JK_Millwright
    Joined: Oct 2015
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    Location: Southwest Florida

    JK_Millwright Master Carpenter


  15. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    dugong

    ========================
    Thanks for the enlightenment, Phil-never heard of a "dugong". Now, thanks to you and wikipedia I know they are similar to the manatees we have here.
     
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