A proa and aero junk or split rig questions?

  • 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
    Deleted user

    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
    Deleted user

    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 | Deleted user
  • 15 Aug 2018 06:48
    Reply # 6574339 on 6368944

    No Bill, the Crab Claw is an amazing rig that works very well! 

    On Why Not? with his single crab claw, I hardly get back winded. On Crystal Clear with her schooner Crab Claw, shunting her without getting back winded was a challenge... The problem was flipping the two sails in synchron, shunting her was hard, single handed was impossible!!!

    pulling the yard up with the brailing lines, is not enough... Now one will need to paddle the boat around, the problem is getting the bow through the eye of the wind... 

    This can become almost impossible, as the wind builds. The stronger it blows the harder it gets. The high bows are the problem, the same reason that cats don't like tacking, hi bows just don't like going through the wind.... A proa is perfectly balanced backwinded, sail up or down, since it's symmetrical, nothing but the sailor will turn it around. 

    Crab Claws??? For a beach proa I wouldn't use anything else! I love crab claws!!!

    The next clip "Heavy weather sailing".... Shows my first crab claw, I was making sails on the beach in 20 minutes, using junk battens, plastic and duct tape. Mid February freezing cold, and success!!! first test of A-D Scull (Mr Doi invented it and he shares it on youtube.) and huge success with crab claws! Low stress, powerful and the vid shows, it will generate power no matter how off your sheeting is.

    https://youtu.be/xcFH5eThi7s

    free standing masts on proas, change the concept completely! Proas are the only multihull that can boast zero aka stress. With the mast on the vaka and a shroud going from masthead to ama, Akas are never loaded, all they do is keep the hulls apart. this is what makes proas, simple and very strong! A free standing mast changes the nature of a proa. The mast will have to be stronger/heavier, the Akas too. The vaka will have to be stronger, where it takes the akas.... It's a nice concept, a proa that can sail Pacific and Atlantic all in one package.... But then what kind of an ama would you put on it? Pacific amas are small and lightweight designed to fly (Russel Browns way of doing things, and I feel he knows his stuff...), such an ama one would not fly when cruising, but it's nice to know one could show off, and fly it at will. Combined with water ballast, the boat could always be sailed in perfect trim, with the ama just skimming the surface. Atlantic amas, are totally different, they are as long as the vaka (a disadvantage in my opinion), because a long ama when sailing to windward in a good chop, will rise to the wave before the Vaka does, like Cats do. Short amas rise with the vaka, or just before is best, in my opinion, as they pierce the wave for the vaka, resulting in a smoother ride and again, minimum aka stress! Aka loads on multies is something one should always take very seriously, because they are huge!, except on proas!

    This is my opinion only, telling others "it won't work..." is something I don't do, because I have heard those 3 words all my life, I went on, and usually things did work, finally....

    It will work! But what are the costs? will the advantages be greater then the disadvantages?? Or..... Why not just build a tacking outrigger canoe???  

     

  • 13 Aug 2018 04:35
    Reply # 6535787 on 6368944
    Deleted user
    sounds like the crabclaw is even scarier than it looks :) I never really thought about it but because they'll develop good lift a wide angles of attack they probably get backwinded fairly easily. I'm really surprised that anybody would build a big shunting proa without designing in some sort of mechanism to deal with the problem.

    EDIT: was thinking about this and a ama mounted foil like the leeboard I'm planning on should solve this problem as the drag from the foil should cause the proa would rotate around the foil till the ama was upwind again.

    can't you just snug up the spilling/brailing lines that pull the yard/boom together on a crabclaw and deal with the problem while it's depowered? that couldn't take to long.

    I'm hoping to manage an unstayed mast so backwinding would be a non issue, could even go atlantic pacific atlantic pacific if I wanted to :)

    The ayrs is an interesting proposition, kind of like the crabclaw, only more so, if one could get it working it would be an ideal proa sail.

    I read about one guy who got into a spin with one and couldn't stop it, had to bail apparently, seems weird.

    If I ever decide to experiment with an AYRS I'll probably rig someway to ditch the sail if I get in trouble.

    I'm working on a way to make a wing of one, something like the amoeba, a wingsail powered land yacht (PDF File attached) that would solve pretty much all the problems with the rig, of course I don't really know anything about sail design or wing sails, but I'm learning fast :)


    Bill

    Last modified: 13 Aug 2018 15:34 | Deleted user
  • 12 Aug 2018 22:17
    Reply # 6528178 on 6368944

    Getting back winded on a proa is never good, and it's frightening when sailing close to land or in an anchorage with other boats or anything that may shift the wind....

    A back winded proa drifts helplessly down wind, if there are hazards not far down wind, you're going to land on them. You may not loose the mast, but you have to get out of this situation ASAP...

    I have learned to sail Why Not? in back winded mode backwards, once moving fast enough I throw the helm over to windward, he will do a 90 degree turn, his bow will just go through the eye of the wind, the Crab Claw will freely fly away from the mast and you're back sailing on a close reach, ama to windward... Kinda like backing your car out the parking lot in the supermarket, you go straight back, turn 90 degrees, put it in first and drive forward....

    James Brett on Free Radical told me he does the same.... He too can get back winded, since he has a stays holding up his mast on both bows of the Vaka. He can't sail in Atlantic mode.

    Bottom line, Getting backwinded on proas is part of the package..... Some proas, the bigger ones, may require you starting up the engine to turn them round, the higher the bows the worst it gets, since you have to get that high bow through the eye of the wind.... I learned that the hard way, on my bigger proa Crystal Clear, in a good wind, getting her right way round after back winded, was hard work. All I had was a sculling oar, no engine, high bows, and the worst rig in the world..... A schooner crab claw, that got me in trouble more times then I could count! A Shunter needs a single sail while shunting. Shunting more sails at once is complicated, with one sail, the boat can easily be brought to a full stop. With more sails, one will always keep driving, resulting in back winding during the shunt.... She taught me that the hard way!!!

    The best thing to do with her, while battling to learn how to sail her for a couple months on the black sea, was to have the anchor and rode all ready to throw overboard, when ever we came into tight situations.... Finally I got the hang of it, but it took all the four hands we had to do every shunt..... Or else Back winded! A schooner crab claw belongs on a cat, not a proa.

    Bill, the AYRS Bolger is a novel idea, but I've never heard of anyone successfully using one. the problem is that the mast is smack in the middle of the sail. The leading edge of the sail is equal to the tailing edge, Junk rigs, lug rigs have a small leading edge and a much larger tailing one.... This helps keep things under balance, I heard about a proa with an AYRS Bolger, that had her captain and crew shitting in their pants on the maiden voyage.... The vessel took off like a racing bike, then suddenly the whole sail would get backwinded, as the leading edge would get caught aback by the wind, the sail would invert inward at the front edge..... The boat would slow, then suddenly the sail would flip out into it's correct position, all at once, race bike mode again the thing would take off like a bat out of hell.... Till wham, inverted the wrong way and the whole rig is shattering and shuddering..... That boat never went out again, her owner sold her, from there on I don't know what happened.

    In my opinion what was happening was, as the boat accelerated, the apparent wind that is now coming from ahead, would catch the leading half of the sail on it's leeward side and weathercock it..... Any other sail, under such circumstances would start luffing on it's leading edge, a tug on the sheet will be all that's needed..... 

    Oh, and a beer........ 


  • 12 Aug 2018 15:34
    Reply # 6519959 on 6368944
    Deleted user

    Being backwinded isn't a big deal unless you're using a canting mast and a crabclaw, which tend to be blown over the windward side of the proa when backwinded unless a mast prop is used. Well, unless you catch the boom with your face :( 

    unintended gybes are a bermudan rig problem caused by the shrouds preventing the mainsail from pivoting forward far enough on a dead run.

    Not that a Junk rig on a proa won't have unintended gybes, just won't happen nearly as often and since the junk rig is balanced it won't be nearly as violent when it does.


    Whether or not the rig would get hung up on the standing rigging and not come down  probably depends on what kind of junk rig you go with, the rectangular aerorig with the horizontal top batton probably would. Certainly something to take into consideration in the design phase.


    I was thinking more like the AYRS/bolger shunting rig, but your right it's using both sides of the sail.

    bill


    Last modified: 12 Aug 2018 15:59 | Deleted user
  • 10 Aug 2018 19:59
    Reply # 6466642 on 6418373
    Anonymous wrote:

     If I do have to have standing rigging I'll probably come up with something that automatically douses the sail if backwinded, after all, the whole point of having a junk rig is safety :)

    Standing rigging only to the beams would take a gybe to interfere with the sail.  Standing rigging to the bows of the lee hull would interfere with the sheetlets.  And if that can be avoided, I would still worry about the sail getting stuck on the standing rigging, and not coming down.  I have no practical experience to tell me whether that worry is justified.

    Anonymous wrote:

    you've probably seen Free Radical wich is so overbuilt I think you could put the sail on either hull and sail atlantic, pacific, or weight to windward if you wanted to, awesome boat, notice the sail is always behind the mast? 

    Like a dipping lug?  I don't think so.  At 0:29 on the video, I see the boat as being on starboard tack, being filmed from downwind, and the mast is visible, to so lee of the sail.  At 0:41, the boat is on port tack, with the mast to weather of the sail.










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