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.