SailNet Community - View Single Post - Building/modifying sailing kayak?
View Single Post
  #16  
Old 09-14-2009
Jeff_H's Avatar
Jeff_H Jeff_H is offline
Moderator
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 6,684
Thanks: 5
Thanked 105 Times in 81 Posts
Rep Power: 10
Jeff_H has a spectacular aura about Jeff_H has a spectacular aura about Jeff_H has a spectacular aura about
The other reason that Gaff rigs still persist has a lot to do with the idea of a boat as system. For the most part, it is very difficult if not imposible to design a true gaff rig or sprit rig that will point as high as as well designed Bermuda rig, which in part results from difficulty controlling twist and in part because gaff rigs usually end up with more drag and weight aloft for thier drive.

But many small boats have hull forms and foils that are not all that efficient in going to weather, so that a small loss of rig efficiency does not hurt the boat's windward efficiency since their ability to go to windward is limited by the hull as much as the rig.

What gaff rigs do well is provide a lot of power when reeching or running without producing as much heeling force. Since the vertical center of effort of a gaff rig is lower in height than an equal area Bermuda rig, the gaff rig can can carry a lot more sail area for a given amount of heeling moment. With modern gear, this can be a pretty efficient rig for inefficient hulls.

The most modern very high performance boats have square head mainsails which offer the best of both worlds. Because they use a cantilevered batten to create the square head they are able to control twist and yet the square head allows them to optimize drive to heeling forces.

This is nothing new. In the 19th century, voyaging and racing canoes used a batwing rig which was essentially a gunter rig with a mainsail with huge roach supported on long battens that improved twist control and reefing. This rig was reefable and often carried a small jib as well.

Jeff
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
Reply With Quote Share with Facebook