Main sail question

[allen-deckard]

This spring I plan on buying a new main sail.

When I was at the anapolis sailboat show I went around to all the booths that were selling sails. Well they all say there sails are the best obviously and I saw more different types of sails than I thought existed.

Well one of the vendors I talked to for sometime mainly cause they were the nicest group of guys and seemed to be the most patient with me

Anyway their sail according to them from what I could understand (there was alot I didn't but thats ok) had basically a line vertically threw the center of the sail that the sail "rotated" on according to them.
Additionally according to them in a puff the sail would flatten out and reduced the amount of heel that the boat would experience because of the way it rotated around that center line.

Ok normally when someone is alot smarter than me on a subject I just absorb what I hear and accept what they say as fact unless in this case they are selling me something then I'm a bit more sceptical. His sails pitch (punn intended) sure sounded good I gotta say that but if something sounds to good to be true it usually is as the saying goes.

SOO my question
Is this bs? I admit that I'm a sailing noob but I cant seem to rap my noggin around how a sail would actually fatten it'self out in a puff in order to reduce heeling. Maybe he was doing a complete snow job on me? I'm thinking maybe he was trying to bring things down to a level I might understand and simplified things a bit to much?

Any opinions appreciated I have no doubt that the sail that I was looking at in the quality construction and materials used was of a higher grade than what I've been looking at but his additional claims seemed ----well-----kinda on the far side of the moon to me.

Thanks

 

[OldCat]

...but his additional claims seemed ----well-----kinda on the far side of the moon to me.

It sounds like bs to me as well, but I then I have no experience doing finite element models of sail cloth under wind loading. So what do I know? Not much, but it SOUNDS like bs.

I'd post this question on this site's sail trim forum, I think that you will get more replies & some from folks who know fluid dynamics and sail cloth.

Go here: http://forums.catalina.sailboatowners.com/forumdisplay.php?f=17

OC

 

[Bilbo]

.............

Anyway their sail according to them from what I could understand (there was alot I didn't but thats ok) had basically a line vertically threw the center of the sail that the sail "rotated" on according to them.
Additionally according to them in a puff the sail would flatten out and reduced the amount of heel that the boat would experience because of the way it rotated around that center line.
........s

The vertical rotational axis of a typical main sail such as is on our Catalina 22 is at the mast or slightly behind buy only about 1". There is no rotational axis on the centerline of the sail vertically on a typically rigged sloop. When a puff occurs, the sail "may" give a bit and so the top of the sail will induce 'twist" more but this amount would generally be very minor. The boat may heel more in a puff and then the horizontal axis of the sail will change which as we say, spills air over the top and limit the amount of further heel by limiting the sail's surface area and influence. If this heels is excessive, then the rudder loses bite and so the boat "rounds up" ....again on the vertical (Zenith) axis of the boat. (Which at that point may not seem so vertical to your puckering orifice.. but will point the sails into the wind and thus cause the boat to regain it's footing.

One or both of two things may have happened at your discussion in Annapolis. Either they were serving BS or you misunderstood their description. Respectfully.
It takes time to learn and understand this stuff partially because of the terms being used but I think that one has to visualize all of these things and how they are used. It's good to study each aspect of the sail, rudder and keel and all of the controls individually. Don Giullette at that Sail Trim forum has some published stuff that may be very helpful. Occasionally, you can find books online or at the library on how to sail. Reading a bunch of different explanations can clear things up.

 

[allen-deckard]

Thanks
I posted the same question on the sail trim forum. One reply was I guess a bit harsh to me because of my lack of tech knowledge I guess. The other answer was a bit or should I say way above my head. But all in all I think I have a bit of a better understanding of it now.

As far as becoming knowledgeable on the subject? I believe I might lean some as I go but don't think I'll ever really study up fully on the subject. I sail for fun will never race will never break any speed records nor will I ever be designing my own sails. I'm a novice and always will be that just likes to sail and will have to take the word of those more proficient in the subject than myself.

I know how to weld and manipulate most any metal in most any environment and know most everything I'll ever need to know about engines. I doubt most people purchasing a car know the finer mechanics of there fuel injection system but have to take the word of those that decide to study up on the subject.

So I'll most likely be purchasing a standard cruising mainsail when the time comes and I'll be happy with my purchase simply because I'll be happily ignorant of what could have been or what should be.

Who knows maybe someday I'll decide to really "know" what's going on besides my general knowledge that I'm gathering from the books I've been reading but as to how and the why's of how things are made I just haven't found an interest in yet.

I appreciate the info and I guess I'm leaning a little toward the side of salesman bsing me a bit not necessarily lying but maybe stretching the results out a bit.

Thanks all and who knows maybe I'll change my mind someday and decide to become an expert.

 

[Bilbo]

Allen, I would not be discouraged by their replies.
From the info that you provided http://www.kappasails.com/products.html#dacronmain
the advantage from this design has to do with the way that the sail is made. All sails are made from individual panels sewn together to form a shape that isn't just a simple flat triangle.
The way that the panels are cut and sewn will affect the strength and characteristics of the sail when you use it. IF you look at this drawing of that sail. http://www.kappasails.com/images/main.gif you can see all of the individual fabric panels edges in black lines and the reinforcement panels at the corners. The main fabric panels generally seem to be a bit diagonal on a line from upper left to lower right and these fabric panels are cut out so that their threads are along those lines. This angle of these panels changes from the panels at the top of the sail as you go down each tier to the bottom of the sail. This manufacturer is contending that sewing these panels this way will stretch less because the basic fabric stretches less if you pull it sideways than if you pull it diagonally (on the bias) http://en.wikipedia.org/wiki/Bias_(textile). Hope that this makes sense. They may also tell you that the sail may last longer before it "bags out" because of this design.
The thing is that like any tech issue, you may be paying a relative lot of money for a small advantage in performance. This is even more true on a smaller boat's sail such as a C22 and on a boat that is less of a high performance type like our C22. I'd compare it to car engines. Some argue the fine points of fancy spark plugs and some are just happy to get any spark at all.
If you are a recreational sailor like me, I'd stick with stock sails. If you are buying, new sails are generally a safer bet unless you know about condition and age of the sail.

Study a bit up on how the sails work and are trimmed. This is partly for understanding but also for you and your family's safety. As the winds kick up out there the potential for unsafe situations rises also. This is not only in how you handle the boat but also in condition of the equipment. There is nothing like trying to get that boat under control after a broach with the wife pitching a fit at ya. ;-)