The Crab Claw - Wharram style - Other style - Videos
In the interest of simplicity, I wondered what would happen if I just got rid of the mast and went with what in effect is a cross between a stayed windsurfer rig and a crabclaw. .
Have you seen
http://www.multihull.de/
Proa special
Riggs
(Tried a direct translated link but it failed)
Can’t find out if any have been built.
Looks like an alternative cat sail version of the Balestron rig. Free standing, totally balanced, light weight rig, not sure how efficiency it is aerodynamically but it does offer other efficiencies. Some high local stresses but modern materials could eat that.
Tink
Could I ask a cheeky favour, could you put a tuft of wool or similar on the yard so us arm chair sailors can appreciate the apparent wind direction a little better
Im the “armchair sailor” here. I have not sailed any boat larger than 5 feet tha last two years. Im just completely obsessed with trying out different aspects of strange proas.
I really enjoy your ideas and your plans.
I will put a thin plastic ribbon on the proa next time I sail it. Im comparing the proas direction with the waves, and I know that is not a reliable way to do it. It was the best I could do today.
Cheers,
Johannes
maybe some videos would be interesting:
Big thanks Grzegorz
I don’t know what you tube has against me but despite hours of searching I have only ever seen one of those before.
Some well sorted proas thanks again
Tink
I have been playing with my Crab Claw Sail setup. I added a “spinnaclaw”-boom just to see how it played out.
I think the Spinnaclaw is great! It makes it easy to adjust CE, angle of attack of the leading edge of the sail, aspect ratio and the amount of upward lift of the bow. I have not test-sailed this yet. I hope there is better (less) wind tomorrow. I still need to build two new smaller crab claw sails with slightly higher aspect ratio.I believe the schooner spinnaclaw could be a very versatile and powerful rig with lots of fine-grained control over many aspects of its function. It seems very fast to shunt (based on a semi-working beta model)
I hope I can post some more pics and/or videos tomorrow.
Cheers,
Johannes
You have brought back a long forgotten memory for me. I built a full scale crab claw rig mock up back in 1988. I built it for my TP01 proa (16ft) when I was figuring out what to do with him at the end of his life. I can remember it all set up in the garden and practicing some dry land shunting. The yards where a sort of I beam of pine and way too flexible. Anyway cutting a long story short a gave the idea up and moved on. TP01 never sailed with that rig. In hind sight things might have been very different if I had built the yards properly
Returning to present day and spinnaclaw rigs etc. I was looking at the pictures and to me the pole needs to go to the tack as you have modelled not along the boom as the original sketch. This however results in a very long pole which sounds far from ideal. So, what about if a track was mounted on the leeward gunwale of the vaka. The pole then connects to the tack of the sail. The tack would pull to the bow as usual but you could control the CE by the position of the pole and the track. Also the sail would be more controlled in the shunt. I need to model it when I am able to do so.
TINK
The spinnaclaw boom works much better on a schooner-rig. The booms can be a few meters long and the yard should be attached to some kind of rail on the boom.
Oddly enough this is one of the few places i like a higher aspect ratio. Since the CC bends it can be very high aspect without all the loads and stress. With a very high aspect CC sail you can bend it to any random shape you want. You can have a controlled twist in any direction and you can adjust angle of attack on the fly, very similar to a birds wing. All with a lightly loaded low stress carbon structure and some dyneema-cord. AC72 eat my dust!
Cheers,
Johannes
Unfortunately nobody has replicated his results.
Those using crabclaws on proa’s or cats have different findings and lower the rig and angle to depower it.
Ayrs says 60% angle. +-
A big part of the rig seems to be booms that have the ability to bend.
Too stiff and breakages happen.
Hi Alex,
we made similar tests with a crabclaw in a windchannel 10 years ago. For example he here three graphs which show the results for different cambers. Explanation of the terms:
Wölbung = camber
Widerstand = resistance
Auftrieb = lift
Grad eg.45° = degree, relative wind angle
The photo shows the test sail without camber in different angles.
If someone is able to translate the whole report from German to English I will send it to him. On the condition to publish the result here at proafile.
Hi multihuller.
With your vast experience with crabclaws, I was wondering when you’d chime in.
One question - why did you decide not go with one on your P12 ?
( I pm’d you about the report.)
Hi multihuller.
With your vast experience with crabclaws, I was wondering when you’d chime in.
One question - why did you decide not go with one on your P12 ?
( I pm’d you about the report.)
Hi Alex,
IMO a big crablaw with more than 30 sqm is not to handle by a small crew on a proa. Especially if you are not sailing in steady wind like in the South Pacific or Carribean. The P12s home will be first the East Sea and/or North Sea, where it’s often gusty and stormy. Hence my premise for the rig was easy handling, and easy reefing.
Whoa. I did not know there had been so much activity on this thread. I’ve been so busy working, I haven’t been checking in.
I really like your mast-less Lateen/CC rig Rick.
If you can make it stable and controllable you will have very low windage and a lot of ways of tuning the sail for different conditions.
....
I like your cat!!
Double thanks. My spar making continues to improve. I’ve been working on an unstayed version. Doesn’t look like it will be heavier. Might even be lighter. It would shunt with the yank of a sheet, and the windage would be the least possible.
ASP - Chinerunner - CC sail upwind
I tested the ASP+CC sail upwind in a soft breeze today. I’m amazed by its upwind capacity. I get it to somewhere around 30 degrees upwind?!? That is pretty amazing for a asymmetric AS hull with a Chinerunner and a polytarp CC sail!
The CC keeps on impressing me!!!
The walap in the link I referenced earlier was said to point that close too. I am thinking that claws are plenty close winded. They just have to built, set up, and sailed right. And yes, lovely day in the vid!
Have you seen
http://www.multihull.de/
Proa special
Riggs
....
Looks like an alternative cat sail version of the Balestron rig. Free standing, totally balanced, light weight rig, not sure how efficiency it is aerodynamically but it does offer other efficiencies. Some high local stresses but modern materials could eat that.Tink
The link I found was this one. On that page is what the Germans are calling a “Y-Rigg.” They show a schooner version, but it’s pretty much the concept I had.
IMO a big crablaw with more than 30 sqm is not to handle by a small crew on a proa. Especially if you are not sailing in steady wind like in the South Pacific or Carribean. The P12s home will be first the East Sea and/or North Sea, where it’s often gusty and stormy. Hence my premise for the rig was easy handling, and easy reefing.
Yep. There’s the kicker. I spent quite a few years in the South Pacific—Hawaii, Johnston, Kwajalein, and Guam. Each island has it’s own wind, but generally, it blows at about fifteen knots out of the northeast for about 330 days of the year. It never, ever stops, and once or twice a year, for a few days or a week and a half, you do NOT want to be out in a small boat. Around the lee sides of bigger islands you get shifting winds, but that is about as tricky as it gets.
So, truly, if you are designing for long runs on the open ocean in the South Pacific, shunting is not the problem it would be elsewhere because you hardly ever have to do it. Having a boat with less than fifteen inches of draft is quite a charm, for you can skim over most coral once you are inside the lagoon, even at low tide, and even the tides are gentle. Getting into or out of the lagoon can be pretty hairy though. That’s probably the most dangerous part of sailing in the South Pacific.
Also, I too have been wondering about the upper limit in size. 30 sqm (~325 sqft) seems to agree with my intuition.
Back to the drawing board and the unstayed mast… uh, it’s not a “step,” more like axle housing. Don’t know the nautical term.
Cheers,
Rick
I don’t really see any advantage of the balanced rig compared to a ‘normal’ balestron rig, which is almost the same thing anyway.
I personally don’t buy the thing about the end plates improving sail performance for a second; while there are significant aerodynamic losses incurred from having a gap between the deck and the foot of a sail (you can lose as much as 20% of the total lift of a sail that way), a slightly wider boom, as an attempt to fake a winglet, is not going to change a thing in that regard, especially with holes in it.
While I admit I might be wrong (if so, please correct me!), to me it just looks like a bunch of extra weight up in the rig where you don’t want it, plus the extra drag just hurting your L/D and thus upwind performance, all for no real handling benefit over a normal balestron rig…
The only real benefit over a balestron, as I see it, is that it should allow quite a bit more jibstay tension (the lack of which limits the balestron, performance-wise).
Hi multihuller.
With your vast experience with crabclaws, I was wondering when you’d chime in.
One question - why did you decide not go with one on your P12 ?
One thing to consider re crab claws is the difficulty in efficient effective reefing. My take is it is a good sail for a day sailor but more problematical as boat gets larger.
Cheers,
Skip
Hi Skip.
a sailor (Reto Brehm) of the P5 has developed a reefing system for his delta sail which may fit also to bigger sail areas. The efficieny close -hauled is a little bit less, as he said, but generally it works fine.
Cheers
Othmar