Evolution Proa Rig, the "LaSHUNK"

Discussion in 'Boat Design' started by rael dobkins, Feb 18, 2018.

  1. rael dobkins
    Joined: Jul 2015
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    rael dobkins Senior Member

    Hi all, back with vengeance...
    here's our new REEFABLE shunting proa rig.
    All d best, BSY.

     
  2. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    Sigh.

    Some people just love to invent the most awkward solution. WITFP
     
  3. rael dobkins
    Joined: Jul 2015
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    rael dobkins Senior Member

    Others just know it all.....
     
  4. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Well it is a complicated solution. And heavy. There are simpler ones available:
    1. Reef the crab claw.
    2. Use a standing lug sail with slab or roller reefing.
    3. Have a fixed junk and move the CLR.

    All of the above have been done, nothing new.
     
  5. rael dobkins
    Joined: Jul 2015
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    rael dobkins Senior Member

    Reefing a crab claw has gone through my mind a million times... How?????? On the water it's more then meets the eye........
    What ever you do the CE goes back, if you choose the easy way, raising the boom, the CE goes up and aft. Not good
    Choose the smarter way by lowering the yard, CE comes down and goes back, O.K.... only that now shunting has just become impossible.

    Lug sail, Junk sail.... about the same thing.... hanging off a fixed mast places the rigs CE almost half the vessels length aft of it's CLR.
    Drawing a scaled down proa with a reasonable sized lug on a fixed mast will clearly show how far aft is the CE. BAD STUFF.
    Forcing you to get that CLR way back fast after every shunt. No way to get the boat to sail it's self ether. lift the rudder and you round up into the wind till you come to a dead stop.

    The fact that it's all been done doesn't mean it's the right thing to do.

    How much weight will I really add, probably almost none.... The crab claw has 2 heavy wooden spars I'm replacing them with the aluminium yard that holds the junk rig (on the model the "yard" that supports the sail) and all the battens that will probably be 25mm aluminium tubes. The only weight I'm really adding will be the rail over the leepod, I think I could probably get the rail and car to weigh around 5 kg. Add to that another 5 kg for extra rigging and what ever i forgot.... it's not that much of a disadvantage if reefing becomes a mere pull of a string.....

    This is a prototype that if proves to be easy to use, will become a cruising concept for a bigger proa.
     
  6. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Reefing the crab caw goes like this: Outrigger Sailing Canoes: Reef that Crab http://outriggersailingcanoes.blogspot.de/2013/09/reef-that-crab.html
    It can obviously still be sailed and shunted.

    I did not say use the standing lug with a fixed mast. You can use it with a moving one, like it is done in PNG for example. In fact you can also use a dipping lug. The only lug that can not use a moving mast is the chinese one. Wich you did solve by using two masts.

    Having a fixed mast works even on a small proa, but I agree it does not make much sense. On a big proa the things are different. You need rudders and daggerboards anyway because steering by weight shift is impossible. Even the original designes used huge paddles for steering. Proas with a fixed mast exist and have sailed successfully for many thousand miles, as you well know.

    On a small proa the rig you designed is a fancyfull complication but it will probably work. I think you will discover that there will be a lot of force on that rail.
    On a big proa that rig will be very heavy. What you call the yard will need to be another mast. Basicly the junk rig has no benefits in small sizes and the handling benefits of the bigger sizes come with weight. Now you propose more weight for that rig. I don't think that is the way to go. Up to about 20 sqm. of sail you can use a traditional moving mast system, either with crab claws or lug sails. On a big proa a standing mast becomes better if you do not have a lot of crew.
     
    rwatson likes this.
  7. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    Yeah, they DO !

    That's why you hardly see any other rigs like this.

    You can tell people who actually sail by the simplicity and workability and performance of their boats versus the "Heath Robinsons" of the water world.
     

  8. rael dobkins
    Joined: Jul 2015
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    rael dobkins Senior Member

    Sigh.............................................
     
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