Kim,

  Are you talking about the same boat and rig that Rudolph described?  Is Mitch?

  The boat in Rudolph's post ( http://wharrambuilders.ning.com/profiles/blogs/sailing-with-pha-tiki-30-n119-1 ) has two unstayed rigs carrying double-skinned wingsails with internal wishbone frames.  I don't see a gaff on the rig.

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  I've been eyeing this rig for a few years now because it's the only workable double-skinned wingsail I've seen that doesn't require hydraulics.  My biggest worries were all the mainsheets, since there would be twice as many on a proa (fore and aft).  That could be a lot of work if short-tacking or shunting up an inlet.

  That said, two large, balanced wighsails would be a very nice performance benefit.

  But if I stick with my current timid course of development, I'd probably settle on an an easyrig with either a flattop main with battens and track, or a wharram-type soft wingsail with a curved gaff.

  I'm currently leaning towards the gaff wingsail because of its simplicity, lower cost, ability to use soft sailcloth, area high up, and ease of stowing.  Regarding stowing, I've got a flattop main on a catamaran, and fitting it into the sail cover with the top diagonal batten requires some inventive origami that's probably not good for a mylar sail.  No problems yet, but I hope to sell the boat before there are any.

  I like the curved gaff for its aesthetics (straight looks better with wharram lines), for the graceful leading edge, and for the shape it gives the sail as the top of the curve twists slightly to leeward.  This last item is particularly welcome after reading people's criticisms of the top 1/3 of a wharram rig having no foil shape.  Though I will admit that I've not heard that criticism from actual wharram sailors.

  Anyway, it's great to hear comments from people like you and brag_rotor (Ben) who have actually used the wharram design.

        - Mike
 


Kim Whitmyre wrote:

 

The owner of that tiki is inexperienced with wingsails. He wanted a walk-under bimini, so he made the mast longer and raised the mainsail higher. This put the mainsheet at a much steeper angle than the original design, thus making the foot too loose, etc.

You simply have to appreciate the gaff in order to raise/lower the wingsail on a tiki: it must be slightly below horizontal. If it is above horizontal while attempting to haul, the gaff will be pressed hard against the mast. To lower the sail,  the gaff is dropped and its weight helps to bring the sail down. My old main dropped like a stone; my brand new main is quite stiff and so doesn't fall as fast, but it soon will. Practice and experience cannot be ignored in any endeavor.


Mitch wrote:

The owner of that Tiki just wrote on Sailing Anarchy about how poorly that rig works, no easy way to hoist or douse, no easy way to trim it or get leech tension.  Says he wouldn't do it again.

On Mon, Jan 4, 2010 at 1:43 AM, Rudolf vd Brug <rpvdb@freeler.nl> wrote: