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I am going to build a Tehini starting this coming spring and after seeing the crab claw rig I am going to give it a go I love the low tech aspect. Is there somewhere I can get more info on the details? Look forward to hearing from you all.

Don Hayes

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I'm sure someone can give specific links but Beat and Beatriz Rettenmund built a Tiki 38 and just sailed it to Hawaii with a $500 crab claw rig. Also, Glen Tieman, who posts on several Wharram forums is a great source of CC rig info. Check out all the Wharram forums, there's a bit of information out there.

Good luck to you.

Bob
I watched the video from eluna and all the ones from have a nice day it looks pretty doable I am going to give it a shot and if it does not work well can always rerig later on. I will be living on my retirement after I get the boat done so the more low tech and inexpensive the better.
Hello ,I had a crab claw on a 16'outrigger for about a year. I sailed an average 1-2 times a week. So I had alot of experience with this rig. I was inspired by the romance of the crab claw like many Wharram folks are. I must tell you the crab claw sucks! The only advantage I could see in the rig is it has a low center of effort and looks cool. The low center of effort is offset by the weight of the large upper spar. It is terrible to windward maybe tacking through 120 dagrees. The rig is dificult to handle in strong wind becuase of the large unwieldy spar up high. It gets even less eficient when you try to reef the sail. There is good reason almost all multuhulls use the fully battened sloop rig. I have sailed on many large multihulls from Florida to Hawaii. So I have some experience in these matters . I strongly believe all Wharrams would perform much better with a modern sloop rig. I would hate to see someone put all the time and money into building a crab claw for a large boat. That is my very opinionated opinion!... Kevin

I think its going to take some time and lots of experimentation to understand and implement a successful crab claw rig on Wharram catamarans, but my experience to date suggests that is it certainly worth the effort.  Our first experiments last summer on our Tiki 21 were with a 4m bamboo mast stepped on the center beam supporting a 7.6m^2 crab claw main.  With a tiny jib, we were able to tack through 110 and get 8-10 knot sog in 15-20kt winds on a beam reach.  This summer we're trying a 13m^2 crab claw main on a 20' aluminum mast in various mid-line positions between the center and forward beams (with and without a bigger jib).

Here's a photo of how we first set it up:


My sense is that the sizing and position of the crab claw rig matter a lot for any given boat.  It may also be important to carefully choose the right material for the spars.  (We've only tried bamboo, but think windsurfer masts look promising.)

Can you post a picture of your boat and rig, Kevin?  Or describe rough dimensions and where rig was stepped on the boat?  Did you have a jib?


We'll keep posting our insights and hope you all will share yours, too.  Here's a spreadsheet that tries to get some measurements from catamarans or proas with crab claw rigs I've read about --

https://docs.google.com/spreadsheet/ccc?key=0AvNvkFFsfh9EdGo3aTlzMz...

And here's where you'll find info about our experiences --

http://econscience.org/tiki

Hi Scott, I think the crab claw look real cool and exotic on a cat. Thats why I  had three diffent ones. I did not have a jib with any of the rigs. I found the crab claw performance very lacking compared to more convetional sails. However, I am tired of agueing agaist them. ...Kevin

Scott Veirs said:

I think its going to take some time and lots of experimentation to understand and implement a successful crab claw rig on Wharram catamarans, but my experience to date suggests that is it certainly worth the effort.  Our first experiments last summer on our Tiki 21 were with a 4m bamboo mast stepped on the center beam supporting a 7.6m^2 crab claw main.  With a tiny jib, we were able to tack through 110 and get 8-10 knot sog in 15-20kt winds on a beam reach.  This summer we're trying a 13m^2 crab claw main on a 20' aluminum mast in various mid-line positions between the center and forward beams (with and without a bigger jib).

Here's a photo of how we first set it up:


My sense is that the sizing and position of the crab claw rig matter a lot for any given boat.  It may also be important to carefully choose the right material for the spars.  (We've only tried bamboo, but think windsurfer masts look promising.)

Can you post a picture of your boat and rig, Kevin?  Or describe rough dimensions and where rig was stepped on the boat?  Did you have a jib?


We'll keep posting our insights and hope you all will share yours, too.  Here's a spreadsheet that tries to get some measurements from catamarans or proas with crab claw rigs I've read about --

https://docs.google.com/spreadsheet/ccc?key=0AvNvkFFsfh9EdGo3aTlzMz...

And here's where you'll find info about our experiences --

http://econscience.org/tiki

@Scott, I'm very interested to hear more about results of your experiments. My plan is to put a crab claw on a Hitia 17.

Why crab claw: my requirement for sail rig is something that reefs fast and simple. I will be sailing mostly solo trolling fishing lures and once a fish is on I want to reef quickly and not worry about sails while I focus on the fish (ono, mahimahi, ahi, marlin e.g big stuff). I have no emotional attachment to any style of rig but of all the rigs out there I think crab claw fits my requirement.

@Kevin: my instinct on using crab claw tells me to lower the clew and hence head and move the tack forward in strong wind and reduced sail area by bringing luff and foot closer (reef). And why not add reef point in the crab claw sail ? Correct me if I'm wrong.

The rig:
Wakataitea is carrying 60qm of sails.
The main sail has 45qm and the stay sail 15qm.
A lot of people ask us if we can reef the main sail and how we do it.
Yes we can and it is basically the same system like on a regular main sail. We have to go into or very close to the wind and drop the sail (spares) into the lazy jacks and tied the reef lines around the lower spar. To hoist the sail again, we have to go again very close into the wind.
Isabelle and I had to make our experience handling the long spare on a moving boat but we learned fast how we have to do it.
Often we leave the anchorage with already one reef in the main sail. It is really strange, even with one reef; the main has still enough power to push the boat fast forward in light winds. Must have something to do with this “vortex lift”.
We can sail till 40 degrees to the apparent wind but the boat will not get very fast. From 55dregees the boat really starts to move but the best angle is everything from 70 degrees.
We reach then easy 6-7 knots in 10 - 12 knots true wind. This is the speed we sail the most time. Till 5 knots speed, you don’t hear any water running along the hull, everything is quiet and you think the boat is not moving.
The real fun is wind from 80 degrees apparent and with 15 knots true. The GPS shows all the time 9, 5 -10, 5 knots speed over ground the miles to go are running down fast. The rig is made for trade wind sailing.


We are very happy with this system and have no doubt that we can sail with it around the world save. It looks beautiful and is an eye catcher. Especially the local people on the islands are very interested in our boat.

since we launched the boat in january 2009, we sailed 18000 NM with it...
all kind of wind conditions on the way...
CRAB CLAW IS THE BEST>>> ;)

Crab claw can have advantages, and most of this has not been reported before. There are radically different rigs being called crab claw, the wharram style and the ontong java style, replicated on wakataitea, for example, have little in common. Although I don't mean to dismiss the other, which the owners are pleased with, I only refer here to the wharram style which has a number of aerodynamic and handling advantages over conventional rigs.

1. The sails have an airfoil shape no matter how they are cut, because the leading edge is more vertical and normal to the airflow than the boom. The closer to parrallel the flow is to the spar the flatter the sailcloth becomes in the direction of the flow. No other sail is shaped by its spars like this, but it requires the upsweeping boom. Putting a jib in front of the sail ruins this advantage because such a sail is more efficient with the draft in its middle.

2. Tilting the sail down not only lowers it but flattens it (as explained above), so the sheet load can be reduced, just when it becomes excessive. When the tilted sail is undersheeted it doesn't become too full because it's supported by the spars. This is effective depowering when close hauled. By adjusting the sheets and tack controls the sail can be quickly tilted up and down to the gusts. This technique is not for use off the wind.

3. All compression is on the stub mast and all bending is on the yard; a structural advantage.

4. Ketch rig makes real heaving to possible, which is the most powerful technique in all sailing. Ketch rig is also optimal for self steering to weather with the mizzen acting as a steering sail and the larger main set for power. Only crab claw balances the area of a low ketch or yawl mizzen with a top heavy main resulting in an even, close to elliptical, vertical sail area distribution of the entire rig. Other ketch rigs have the preponderance of sail area along the deck.

5. The sails automatically flatten in higher wind speeds because of their exceptionally bendy spars. Jibs inevitably work oppositely.

6. Drag producing halyards, shrouds and mast are all limited to the lower half of the rig reducing weight and windage aloft. The short masts also create much less windage and weight aloft in storm conditions at anchor and at sea under bare poles, also when motoring (doesn't apply to me). The mast on the windward side of the sail puts its windage in an area of reduced and aft shifted airflow.

7. The aft leeward shroud can be untied, passed between the yard and mast, and retied aft of the sail so that the mizzen can set directly out to the side of the boat with no chaff. This eliminates the adverse affect a mizzen has on steering when the wind is abaft the beam making the mizzen an effective sail on these headings. It is easily done with the sail standing, which is impossible with any other rig. This is an advantage of the utmost importance in real sailing.

8. When the halyard is released the sail can not fail to instantly drop.

9. An effective new mainsail can be easily hand sewn out of polytarp for less than $100, because the spars support and shape the sails. The whole rig is unbelievably economical for the self-builder, the long bendy spars being the hardest part.

10. A runaway halyard can be reinstalled from on deck with a ten foot stick.

Vortex lift is not generated unless the leading edge of a foil is tilted back more than 45 degrees in the direction of the airflow which obviously doesn't ever happen to crab claw. Ironically leading edge attached vortexes are probably generated by the gaff on a wing sail over the sail's head.

Reefing can only be done when the sail is completly dropped so has no advantage. It is easier and quicker to put up a separate smaller sail and this will have better shape and smaller, lighter, optimal spars. This switch is easier than changing jibs, and with the short mast results in a better, cleaner reduced rig than any reefed rig, since it carries no bare masthead up at the top.

Nobody should try something really unusual like crab claw unless they are willing to devote their life to experimenting, failing, modifying and analysing it. Definately not for today's consumer cruiser.

".....Definately not for today's consumer cruiser." hahaha  glenn, i like this one.....

Please, try the crab claw on a small boat of some kind even a monohull. Sail the boat with a conventional sail then switch out the rig for a crab claw. Keep the sail area and the sailing conditions the same. Try them both out in a varity of winds and courses.  This will give you a good apples to apples comparison. Its a great way to learning about sailing the crab claw as well. 

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