Join Date: Feb 2000
Location: Annapolis, Md
Thanked 163 Times in 133 Posts
Rep Power: 10
Re: Bob Perry's take on Wolfenzee's dream boat
By actual measurement on the drawings with your shortened boom, the difference in sail area between the the hollow leech that is required to go battenless and the amount of roach that you can get without having to worry about the battens hitting the backstay, comes to over 15% of your mainsail sail area or roughly 8-10% of your overall effective sail area. That is a lot of sail area to give up. Whatever you do is of course up to you, but I want you to understand that the sail area being lost is not insignificant. So in addition to shortening the life of the sail by not having battens, you are also giving up a lot of reaching ability, or the ability to use a smaller, more convenient genoa for example.
Regarding Tanbark sail cloth, you need to understand that there are comparatively few manufacturers of quality sail cloth in the world so the options are limited by these few weavers. And they are influenced by the fact that Dacron is not dyed the way cotton or other fabrics are colored. In dacron the color comes from compounding the color into the polyester molicules, displacing some of the actual polyester itself. So, because of the way that dacron works, the addition of color means that there is less 'structural content' in the fibers that make up yarns that make up the threads, that the sail cloth is woven with.
Because of that, a dyed dacron sail cloth starts out being a little more stretchy for any given weight, than a plain white dacron, and quicklly becomes even more stretchy over time. Compounding this problem is that you cannot temper dyed dacron in the same way as you temper conventional sail cloth. The way sail cloth is made, the thread is woven and then tempered under controlled condition in which the fabric is heated, which shrinks the thread and makes a tighter weave and the fiber stronger and more durable.
Because of that, once the compromise is made to dye the yarns , the sail cloth companies make an assumption, that anyone buying a dyed dacron is looking for a 'comfortable hand' rather than fully optimized structural dacron sail cloth. In other words, the sails start out less stable, (more stretchy), which is never a good thing since it means reefing sooner as the wind builds, and shorter lived.
The industry refers to these dyed dacrons as novelty products and when I researched this for a friend a few years back, there were no sources for fully structured tanbark dacron. Its just the way it is....
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
Last edited by Jeff_H; 06-18-2013 at 08:40 AM.