Square tops

The boat feels "sticky" in light winds, essentially its easy to stall the rig in light winds. We have had to learn how to flatten the fully battened sail so that the flow remains attached. This has been achieved by reducing rig tension to straighten the mast whilst also experimenting with kicker to control the roach twist. Put another way - when the H2 first came along it seemed like we could sail to our PY in medium or heavy winds but when it went light we got a total kicking in PY racing but after several years of trial and error we have found some new "gears" that keep the boat powered up as the breeze falls. Hope that helps?

See the old thread I bumped.

I also found a thread about the re-hash of the RS400 rig, when they tried a square top main and rowed back to just changing the cloth:    

 

https://www.yachtsandyachting.com/forum/forum_posts.asp?TID=7237&PN=4&title=rs400-proposed-changes

    

Divided opinion. some were very positive about the square top, but as I recall, it looked very nice but got spanked by Merlins around the cans?

Originally posted by ChrisI There's no question that for us a square top rather than a pin head is not fashion but a key part of the design - in light wind conditions and esp when tide and wind are from the same direction we go forwards when other boats are going backwards.

That's just area high up though?

You can think of a square top as either a triangular sail with roach added by a long top batten, or as a triangle with the top cut off.

You could get the same light air performance with a taller mast and more triangular sail?

It's all comparative and with a SMOD you don't really have a sensible framework to say square top is 'better'.  Better performace per sq ft of sail? Better performance within the limits of mast length? Better performance within a £ budget?                                                                         

                          

In a development class, we're talking about best performance within an arbitrary set of rules which 'tax' roach to arbitrary degrees.                                                    

                          

So what baseline do we use when evaluating a square top's all round performance?                                                                  

Presumably what we want is a rig which keeps the heeling moment constant as the wind increases above the design point of the crew hiking/trapezing to the max? Is that more about the squareness of the top or the characteristics of the mast etc? Can an elliptical sail ever be as good in this respect?                       

          

 How do we model this when designing a rig? How many rigs are actually rigorously designed and how many are just a case of sketching a sail and see how it goes?