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M. W. Schacht



The Spinnaclaw

The boys in the lab have been working overtime on a new invention, and I wanted to give you a sneak peak. Internally we call it the spinnaclaw, however marketing is still testing the final brand name with focus groups.

As the name implies, it is a cross between a crab claw sail and a spinnaker, sort of a Scandinavian/Polynesian hybrid. The idea is to mount the crab claw boom to a spinnaker pole, and shunt the sail like a big asymmetrical chute! The reasons you would do that:

  • Quicker shunts. The radial motion of the spinnaker pole combined with the fact that it travels only half as far as the traditional rig fore and aft should make for snappier shunts.
  • Better helm balance off wind: traditional crab claws develop powerful weather helm on off wind courses, the result of all that sail hanging off the leeward side. The Spinnaclaw shifts approx. 20% of the sail area to windward as it bears off, thus reducing weather helm.
  • Quickly adjustable CE. The pole can easily be shifted fore and aft while under sail, fine tuning the sail’s center of effort and helm balance for all courses. A nice feature for a boat that steers by weight shift and the occasional steering oar.
Posted: 23/Aug/2008


Comments are closed for this entry.
Wade Tarzia said:

Nice idea. Make it so!—Wade

Posted: 30 Aug 2008 - 6:34
peter southwood said:

I like the idea, it could make the crab claw rig much easier to use for a small crew. May even be practical to single hand a fairly large rig.
The name leaves a bit to be desired.
Cheers,and keep working on it

Posted: 31 Aug 2008 - 12:21
Harmen Hielkema said:

Hi Michael

The idea has an “I wish I’d thought of it” quality about it. I’d love to give it a test run on Takapu!

P.S. Your renderings are splendid.



Posted: 31 Aug 2008 - 12:58
Arlow said:

I think you may have developed a system for single-handing a crab claw rig.

Posted: 31 Aug 2008 - 9:45
Ricke said:

Hi Michael,
I haven’t been to the site for several weeks - lots of new and interesting stuff. The Spinaclaw looks very interesting! How would that work on Pookie, would it solve the problem of getting the tack far enough foreward?

Posted: 08 Sep 2008 - 10:11
Editor said:

Hi Rick,

Yes, it is yet another way of moving the CE forward, so it would work.

Posted: 08 Sep 2008 - 7:19
Isa y Massimo said:

Hi Michael,
we are two cruising cat builders and we want to change now to proa building. Now we are into building a 16 feet beachproa and we like the spinnaclaw (the name is good ). Later we want to build for our personal use a 16 m cruising proa,
inspired by Taylor designs. In your Taylor special you refeer on a german book we also have (Abb.115). The man who wrote that book had an interessting rig solution too there is a picture with a traveller track on the leeside of the hull
that should do the same? as the spinnakerpole.(Abb.113)Do you have the book ? Can you give us a comment ?

Posted: 24 Oct 2008 - 5:18
Editor said:

I do not have that book, just a few old photocopies from it that a German proa fan sent me a long time ago. In any case, the traveler track on the lee side has been used more than once on small proas, so it works. The Spinnaclaw is an idea about how to do the same thing but with a pole.

Please keep us updated with your 16 foot proa!

Posted: 24 Oct 2008 - 11:26
Christian P.J. Bahnerth said:

A great idea; however, I pesonally like the schooner rig as it give the sailor all the control he wants by using his air rudders.
All the same I’d like to see this implemented and tested against other rigs.
Kind regards

Posted: 16 Jan 2011 - 9:10
David Nesbitt said:

When I first saw the sketch of Spinaclaw, I saw a traveller on the lee gunnel. If you were following a traditional assymetric hull, the side is, for all practical purposes, straight. 190-200 sq.ft. on a 16’ would improve the balance if the sail height was kept low.

Posted: 12 Apr 2011 - 5:55