A proa and aero junk or split rig questions?

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  • 28 Aug 2018 00:19
    Reply # 6641707 on 6368944

    things are going much more slowly than I would have liked, but Larry Daryl and Daryl is coming along nicely, just need to get the daggerboard rigged so I can move it back and forth and flip it if I decide shunting is doable and I can throw her in the water. Oar steering and I'll be using the sail from my dinghy to start, but once I get it working I'll start on a new junk sail.

    I put the mast step at the CLR, she probably won't go backwards all that great but I thought I'd try :)


    Billl F

  • 19 Aug 2018 08:10
    Reply # 6582216 on 6581024
    Bill F wrote:

    ran across this paper on wind tunnel tests on 10 different micronesian sails, though someone might find it interesting, wonder if anyone has ever done anything similar with junk sails. 


    Bill


    This could be interesting, and I see it originated just down the road from where I live. I am building a little 6 meter cruising catamaran. I would love to have a junk rig on the boat but I don't think it is going to work out for a variety of reasons. My next best option is the designed gunter rig, which is an 'alternative rig' these days. But perhaps some type of Micronesian/Polynesian rig warrants at least a certain amount of investigation.
    Last modified: 19 Aug 2018 08:11 | Anonymous member
  • 18 Aug 2018 13:31
    Reply # 6581024 on 6368944

    I think part of the problem is needing a military escort for part of the way to protect against pirates.


    ran across this paper on wind tunnel tests on 10 different micronesian sails, though someone might find it interesting, wonder if anyone has ever done anything similar with junk sails. 


    Bill


  • 17 Aug 2018 20:55
    Reply # 6580155 on 6578702
    Anonymous wrote:

    Man it just sucks that he can't get a decent price for Nixie, that's a nice boat and from the build thread it looks like he did everything right, I mentioned it to Mark T. he liked the price but he wasn't too thrilled with the location, and he was thinking pounds sterling not USD, so it's about 22% less than he thought.

    Shipping or paying a delivery skipper to sail the boat might be a tad expensive.  Then again, even new boats are commissioned from yards in Asia.  

    I wonder whether there are sailing vloggers who could make a living by sailing an unusual boat without being paid anything extra, and who are competent enough to be trusted with the boat.  Dylan Winter, of Keep Turning Left?

    This here might be a useful resource for building small proas: http://expandacraft.com/shop/



    Last modified: 17 Aug 2018 20:57 | Anonymous member
  • 17 Aug 2018 12:54
    Reply # 6579386 on 6368944

    Now that is a beautiful boat!

    Garry Dierking calls that type of mainsail a the tacking crabclaw, although he hangs his on a stub mast. It basically trades off most of the versatility of the crabclaw for control.


    The Wharrams with crabclaws don't shunt, that's where the crabclaw is a handful, moving what is essentially a giant kite from one end of the boat to the other can be pretty hazardous in heavy weather.


    I don't think the super tanker shunts either, wouldn't that be something to see? :)


    Bill

  • 17 Aug 2018 06:18
    Reply # 6579034 on 6575421
    Bill F wrote:

    I realize the crab claw is a great sail, just not single handed, the islanders had a crew to keep things from going pear shaped while the biggest guy picked up the sail and walked it to the other end of the boat, nowadays it's tough to find one person who wants to use a crab claw, let alone a crew. From everything I've read, the word that best describes singlehanding a crab claw in heavy weather is "Scary" I'd certainly shy away from using them on any kind of cruiser, and that's what I'm working on, designing and building a cruiser, if it wasn't a proa I'd just have 3 or 4 different sized crab claw sails and use whichever one was the right size for conditions, but a proa can't afford the extra weight.


    I have seen a Crab Claw rigged, (2 sails), Wharram Tiki 38 catamaran in New Zealand. It had crossed the Pacific Ocean from the US, and spent several seasons sailing between NZ and our nearby Pacific Islands. The owner seemed quite happy with the rig.

    We also have quite a few sailing Waka in New Zealand, (pic below). They are recreations of the sailing catamarans which the early Polynesians voyaged across the Pacific Ocean, and eventually reached New Zealand during the 11th/12th Centuries. I don't think these are a Crab Claw rig, maybe a hybrid, but they seem to work fairly well. The photo is of a single mast rig which has a headsail. The two masted rigs do not have a headsail. I have even been thinking about the rig for the catamaran I am currently building, but I think maybe too much sail high up. Perhaps not the rig for a flighty little six meter catamaran! 

    Last modified: 17 Aug 2018 06:34 | Anonymous member
  • 17 Aug 2018 00:56
    Reply # 6578702 on 6368944

    Thanks Robert, I'm really glad I didn't order that book, I woulda been so ticked!

    Great links on the foil and shifting ama, thanks, good to know that I can find catalyst magazines here too, found an index online so that'll be really handy :)

    Man it just sucks that he can't get a decent price for Nixie, that's a nice boat and from the build thread it looks like he did everything right, I mentioned it to Mark T. he liked the price but he wasn't too thrilled with the location, and he was thinking pounds sterling not USD, so it's about 22% less than he thought.


    Hey Rael, thanks to your suggestion of a shunting sailing canoe I'll have a small proa in the water in just a couple days :)

    I built a olympic style sculling boat a couple years ago and was about a week from being done when I got really bad tendonitis from rowing, so I stuck it in my garage behind some boxes and did my best to forget about it.

     After I read your post I remembered it and went to have a look, there were a couple little amas I made for my dinghy and didn't like with it, I'm going to glue/screw a 2x2 to them to make them one ama.

    Built the mast step and glued in some doublers and reinforcing, and most importantly, came up with a name, Larry, Darryl and Daryl, larry is the fat one :)


    Well, glue should be dry, back to work :)


    Bill

  • 16 Aug 2018 05:43
    Reply # 6576341 on 6368944

    Bill, 

    It seems you know what you want to achieve....

    Dreams are what makes us live, when they come true, we feel alive......

    Go for it, it's not gonna be a walk in the park, that much you know.

    My experience taught me, START SMALL!! keep it cheap and simple, allow failure to teach you without breaking you.......

    Then go BIG!

    Good luck bro.

  • 16 Aug 2018 00:04
    Reply # 6575878 on 6575421
    Anonymous wrote:

    Joseph Norwood had a Bolger falcon class proa with one and said it was a dream to handle, self tending for miles and very well behaved. pretty tough to find any real data on it though and buying Bolgers books are pretty pricey, if I had any idea what was in them I'd get them though.

    I have the book in which Bolger describes the proa that Norwood built.  As far as I remember, that chapter has little information that is not in Norwood's article in Catalyst, and Norwood can tell you something about how the boat sails.

    Anonymous wrote:

    I'm trying to come up with a way to put water ballast on a "Sled" of some sort that runs on a track under the deck between the hulls so the skipper could quickly move the ballast further out towards the ama in response to gusts and bring it towards the vakka in light air.

    An alternative is a hinged Bruce foil.  You can find the theory in AYRS Catalyst 23.  JRA has a subscription, and you can get them through this site, somewhere.  I have my own subscription, so I haven't checked where.  Videos of proas with hinged Bruce foils, called vector foils by a recent proponent, are at:

    https://www.youtube.com/watch?v=1pK4olWjm2k

    https://www.youtube.com/watch?v=fWOiF49logI

    https://www.boote-forum.de/showthread.php?t=119396&highlight=proa&page=2

    Nixe has that foil between the hulls, the model and the daysailer outside of the hulls.  That Catalyst article shows some calculations of the effects that should have.

    Nixe is for sale, by the way: www.proa-nixe.ch  Price is quite low, because there is not a big market for proas, and because the boat is in Thailand.

    Anonymous wrote:

    I've been trying to come up with a way to move the ama fore and aft on the shunts to balance the rig, probably not doable but if one is planning around a folding system for the akka anyway it might be possible, with an unstayed mast anyways.

    There is an example here: http://wikiproa.pbworks.com/w/page/14592443/Doug%20Taylor%27s%20variable%20geometry%20proa%20from%201977

    Another boat currently being built is a 9.5 metres long proa based on the CLC Boats Madness design, described in Catalyst 51 from page 7.






















    Last modified: 16 Aug 2018 00:05 | Anonymous member
  • 15 Aug 2018 19:26
    Reply # 6575421 on 6368944

    I realize the crab claw is a great sail, just not single handed, the islanders had a crew to keep things from going pear shaped while the biggest guy picked up the sail and walked it to the other end of the boat, nowadays it's tough to find one person who wants to use a crab claw, let alone a crew. From everything I've read, the word that best describes singlehanding a crab claw in heavy weather is "Scary" I'd certainly shy away from using them on any kind of cruiser, and that's what I'm working on, designing and building a cruiser, if it wasn't a proa I'd just have 3 or 4 different sized crab claw sails and use whichever one was the right size for conditions, but a proa can't afford the extra weight.

    I don't have any plans to experiment with them beyond installing plywood doublers to support the hardware for a crab claw rig if I do decide to try one, and the first experiments will be finding a workable system for reefing the claw.

    If I do decide to mess around with a potentially out of control sail I'm finding the AYRS/Bolger shunting rig quite intriguing, Joseph Norwood had a Bolger falcon class proa with one and said it was a dream to handle, self tending for miles and very well behaved. pretty tough to find any real data on it though and buying Bolgers books are pretty pricey, if I had any idea what was in them I'd get them though.

    I see what you mean by the unstayed mast changing the nature of the boat, but it does have some serious upsides too over and above eliminating the worry of backwinding, for instance, you don't have to worry about the ama shaking the wind off the sail in light winds and chop every time it hits a wave, of course in that situation there's no good reason not to loosen the stay so it doesn't happen.

    You could also make the argument that by eliminating the possibility of backwinding you could make the beams lighter because they don't have to carry unexpected heeling forces.

    I realize that standing rigging has some great upsides, I just don't think that they're worth the tradeoffs, if I did I would probably just be another bermudan rig sailor.

    I'm designing around a usable deck between the hulls and a comfy bench as well as using the ama for a dive platform, also, foils on the ama place a lot of stress on the akka that wasn't a problem for the islanders so I'm planning on a third akka anyways, fairly sturdy, but not as heavy as you made thor :)

    I'm trying to come up with a way to put water ballast on a "Sled" of some sort that runs on a track under the deck between the hulls so the skipper could quickly move the ballast further out towards the ama in response to gusts and bring it towards the vakka in light air.

     I suppose you could use a single stay with a shock cord on it so it wouldn't  interfere with the sail on a gybe but would tighten up and carry the ama if it lifted out of the water.

    I'n really not at all sure about how I'll shape the ama above the waterline but below it'll be a deeeeeeeeeeeep vee with a fair amount of rocker, I'm planning on a round or flat bottomed vakka so the ama is going to have to provide some resistance to leeway. Since I plan on using the ama as a dive platform it's going to be oversized anyways, it'll be too light for real atlantic proa style sailing, but if I need to tack around an obstacle and I don't have time to shunt I'll be able to

    I've been trying to come up with a way to move the ama fore and aft on the shunts to balance the rig, probably not doable but if one is planning around a folding system for the akka anyway it might be possible, with an unstayed mast anyways.

    The Proa I'm working on is designed to experiment with, well, just about everything, it'll have mast steps and partners in both ends and the middle as well as everything I need to mount the hardware for a canting mast rig. I'll be able to vary the rocker, move the ama further out, make different underwater profiles and attach them, experiment with rudders in different places and move the leeboard by over 60% of the waterline. I'm in the process of designing and building a 9m coastal cruising proa and I'm gathering and testing/researching data/ideas.

    I've been working on a sculling boat that will make a great tacking outrigger canoe with very little extra work, thanks for the idea, I can use it to test out my leeboard and it'll give me something to sail when I'm modding my vakka.


    Bill



    Last modified: 15 Aug 2018 19:35 | Anonymous member
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