New Sails... opinions

Welp, sailing season is over up here and I was going through all of me rigging. I am thinking about buying new sails for my Nacra.

More than likely I am going to go with a square top. The big question is 5oz. Dacron or a laminent sail (dyneem, mylar, kevlar...). Anyone have both? Got some upsides and down sides for me?

For all around sails I have had the best luck with Pentex (a mylar) and the dacron Tornado cloth. The Pentex is a little faster and the dacron a little more forgiving (it works well over a wider range of settings (or screwups)).

Carl,
I agree Pentex is a very good option. Kelvar does not have enough give and Dacron has too much.
Did you know pentex is actually a by product of the automobile tyre industry. Makes a mightly good sail.
Regards,
Phill

Carl,

All agreed.

I've been discussing the alternatives for my sails with the (reputedly) best multihull sailmkers in Brazil, Cognac/Elvstrom and they sent me one of their published articles where they (basically) say that:

a) "Rigid" sails (3DL, reinforced film, etc.) have one important shortcoming - since they are not flexible, they can only be relatively more efficient in the tight wind speed range they were designed for.

b) "Flexible" sails (Dacron and others), if properly designed and cut, have a wider speed range where they are efficient, making better all-around sails. They can be more efficient then rigid sails, depending on the frequency and amplitude of the pressure changes in the specific day.

c) Sailmakers prefer rigid sails because more sails are needed in a complete inventory, with obvious $$$ consequences.

d) As a consequence, sailmakers generaly downplay the merits of flexible sails - which, by the way, are more difficult to design and cut.

Also, they claim that rigid sails do not maintain the design shape they are supposed to. Their practical metaphor was: when you cut an avocado in two and eat the pulp of both sides, the remaining half-shells do not match anymore only because the pulp (mold) was removed. A similar thing happens with rigid sales, although obviously in a lower scale. After they leave the mold, they do not hold their shape for long.

Cognac-Elvstrom has access to cheaper labour costs in Brazil, so their flexible sails are relatively inexpensive (and reputedly excelent to all but grand-prix racing). Since they also do rigid sails, it is easier for them not to have the same bias.

However, although all this seems logic and reasonable, I am just summarizing their opinion and am far from being an expert.

Cheers,

Hmm, it was a bit of a surprise to me that Elvstrom was advocating Dacron..

Anyway, at this years IDM (international german championship) I think I counted three dacron jibs. The rest of the jibs and mainsails was Pentex. Some of the top ranked teams was there (Bundock, Gaebler, Polgar, Sachs..) and they all used Pentex jibs/mains. Cost is not a big issue to these guys, so if Dacron was better they would have used it. Especially since you only are allowed to measure in one set of sails for any event.


I have a Pentex mainsail on my Tornado, and are very pleased with it. I like it, especially when it really blows. In contrast, my Dacron jib is awful when it starts to blow. Also, I find Pentex sails to have better durability than Dacron sails. Going for a Pentex jib next season (and Pentex main + siliconised spi if my sponsor (wife) agrees )!

I would stop worrying about the material (Pentex of course) and rather start evaluating sailmakers.

Did I mention that I like Pentex sails ??

Thanks for the info - it will certainly help me choose the sailcloth. Will check Pentex prices now.


They are not. Cognac is Elvstrom's representative/connection in Brazil, but the article is not signed by Elvstrom, only by Cognac. (also, the sails they make are different and use different sailcloth).

Very probably their article targets cruisers wondering what sailcloth to choose. Racers will take the last 0.1% extra speed and pay the price.

Cheers,

Hello Luiz-

Is that you in the pic??

thom

Yes, I liked sailboats even before K3. That's my very first photo on a sailboat, taken in the same club in Ipanema where I learned to sail later on.

The mono is a "Sharpie" class (plywood, hard chined, with a steel plate centerboard and steel plate pivoting rudder). They were relatively popular in Rio at that time, but not as much as other plywood boats, like Snipes and Penguins.

Cheers,

Is there any reason why you wouldnt consider Cuben, or CarbonX? I have been running a CarbonX Smyth Main on my F31R and It has been great, The jib however has shown more wear after 3 years of racing the mylar has proven to be the weak link, mostly because the jib is a 110 Blade jib, and rubs the spreaders when tacking. However the Main has no signs of wear!

I thought it was pretty simple and I'm getting confused about how a stretchy sail can be an advantage. Dacron is less expensive than the laminates and as things go...you get what you pay for. Dacron will not maintain it's shape as long. The laminates utilize the stiffer and stronger scrim materials (pentex, kevlar, carbon fiber, etc.) so that they will maintain shape better and longer.

On our cats, why do you want a stretchy sail? If it's blowing hard and I'm trying to flatten/depower my sails I would think the last thing I want is for the sail to stretch and become fuller (and/or loose shape).

Jibs, however, go through a lot of flexing and bending crossing the mast and all the hardware up top during tacks and gybes. Laminate sails are not good at this constant flexing but Dacron is. Because of that we see a lot of Dacron jibs.

Stretchy sailcloth can be used to make sails that flatten when the pressure increases. For this reason, they are useful in a wider range of wind speeds and replace more then one rigid sails, which are more wind-speed specific.

A stretchy sail is slower then the two or three rigid sails it replaces - if you can always have the proper rigid sail up. However, the wind speed may be very variable and eventually you'll be caught with the wrong sail up. Also, in these conditions you'll have to change sails more frequently, making the stretchy sail a better choice.

Summary: a properly designed stretchy sail (one that flattens with higher pressure) is an advantage in highly variable conditions.

Durability is a separate issue.

How does a stretchy sail flatten as it reaches higher pressure? The stretching that you refer to - is it due to pressure generated by additional downhaul (cunningham) and main sheet?

Perhaps to a lesser degree but the lack of stretch in composite sail cloth is easily offset by the amount of bend induced in the mast is it not? Mine looks like a bananna when we're at full depower mode. My question is, with the adjustment range that we (cats) have isn't a stretchy sail is less necessary?

About the sail that flatens authomatically when the wind increases, all I know is that it is a tri-radial design that was developed by Lars Grael (former Tornado Olympic Medalist) and Arnaldo Andrade (Cognac Sailmakers) many years ago.

If you want more information, I suggest you write directly to Arnaldo Andrade (adrianno@openlink.com.br). You can mention this forum and my name if you want, but I don't think it's necessary - he will probably reply anyway.

Cheers,

First stretchy is relative.

Dacron and mylar both stretch. Mylar does not stretch as much.

Dacron has the same strength and stretch in all directions mylar does not. That is why layout on mylar sails is important. The material has to be turned so that the load is in a direction where it is strong.

Forgiving on cat sails. If you don't have everything set just right on a Dacron sail, the load will stretch it out a little. With a Mylar it will wrinkle and look like you have too much of something and not enough something else. Also if, the Sailmaker slipped up a little or the fabric gives in a local area Dacron will stretch. If a small section of a mylar main yields, it can look very ugly.

All this being said, the best sail I have ever seen is an Ullman pentex 18 sq, a scaled version of the new rig Tornado main

Actually...

A panel of dacron will have its strength in only one direction (both ways), because of the way the fabric is weaved from fibers. One a square piece, the strength will either be up and down or left and right. Generally, on a long roll of cloth the strongest direction will be from side to side, not along the length. But it also comes with the strength lengthwise.

On our normally panelled Dacron main and jib sails, the seams for the panels are on the battens, meaning the cloth is rolled out side to side on the sail and sewed together panel-wise going up, giving the strongest part of the cloth to take the biggest loads, mainly up the leech and luff. Anytime the force goes out of alignment with the direction of strength in the cloth, it will stretch and ultimately deform. This way of making sails obviously can't account for the fact that almost no load on the sail will line directly with the strength of the cloth.

Radial cut jibs and mains are an attempt to line up the strength of the cloth with the loads on the sail. This is a case where the strength in the cloth is lengthwise. But again, for all the effort, the load paths will not always line up with the strength of the cloth, leading to stretching and deformation.

Other types of cloths used in panel type construction attempt to have strength in more than one direction, but ultimately will still not be able to exactly match load paths. Still, an improvement. Most of our mylar sails are radial cut fabric laminated with the mylar. Same issues apply ultimately, depending on the directional strength of the cloth used.

The modern laminate sails, place fibers in the sail to directly correspond to the load paths, then laminate it all together.

Sorry, couldn't resist, from a lecture on sail materials from our local North shop...

What is being said here flies in the face of everything that has been learned within the windsurfing community for the last 30 years.
When Dacron was used, the rig was easy to overpower and had a very narrow wind range…the Dacron/Mylar laminate was better…then battens were added which helped increase the range, then camber inducers to force more shape into the sail. All these things helped, but when the sail manufactures started to use Mylar film and scrim/Mylar sandwich things really started to happen…all the sudden one sail could cover the wind range of 2-4 Dacron old school sails.
The designer could then design the shape into the sail and be sure it would keep its shape in a wide wind range, if set on the correct mast and used with low flex carbon booms…
The sails became much more responsive to tuning…if you set the down haul or out haul a certain place, it stayed there until you changed it…the wild fluctuation of center of effort in the sail was now gone…as the wind picked up by proper adjustment of the down haul and out haul the center of effort could now be brought down lower and moved forward on the sail making it more controllable, with the head bleeding off excess power that would slam a sailor with similar size old school sail under equal conditions.

You can’t keep the design foil in as wide of wind conditions if you have a fabric that is constantly changing shape. Dacron is generally cheaper, and more resilient to rough handling, although I have had just as many Dacron/Mylar windsurfing sails delaminate as I have Mylar, mylar/scrim/mylar sails.

Bob

that's what I'm talkin' about!

You are right. The said article agrees that it claims the opposite of what all of us believe.

I'll try to have the quoted sailmaker read this thread and explain his point.

My best guess is that the rigidity of the sailcloth is not THE reason behind the improvements in windsurfer sails.
Those are probably linked to better masts (mostly) and to the other features you cited.

Cheers,

I wish we could get Dave Calvert to comment on this, he is the only well known sail designer I know of that has been deeply involved with both Windsurfing racing sails and Catamaran racing sails…he is uniquely qualified to explain what may or may not work when translating sail design from one discipline to the other…

You are right to point out improvements in carbon mast design and construction, and also low flex carbon booms as having a major impact, but having a more stretch resistant sail material to work with was touted by all the major sail makers (Pride, North, Gastra, Izzy, Sailworks) as the vehicle that allowed them to build in more shape to the sail, and to lighten the sail by not using so many mechanical features (battens, camber inducers). Many of the sail makers have developed camber free designs that have a more stable shape then the camber induced sails just a few years ago. When you have a whole industry that is tech driven, and very competitive aligning so strongly towards one design feature (stable sail material) it makes some rouge statement (even by a known designer) a bit hard to swallow.

Bob

While we wait to see if Arnaldo (writer of the article) answers my request to step in or send me his reply, I'd say that what sailmakers tell customers is naturally biased by their specific business needs (as anyone's, for that sake - no recriminations). More resistant materials mean less stretchy materials. But it also means less weight, less work (aligning panels' stronger direction with stress lines is time consuming) and more profit (higher cost materials + less work time + same profit % = more $$).

Add the fact that rigid sails ARE superior in racing conditions - when everyone is supposed to wear the sails that best suit the conditions most of the time - and the rigid sails sells themselves. And what would anyone atribute the performance to? The sailcloth, naturally.

But what he said in the article is that the story is not necessarily the same when you are cruising, when the pressure is very volatile, when the cost of aligning those panels is less important in the total cost of the sail and/or your rig is less high-tech then windsurfers (or some beach cats). Jibs, for example, are a lot more dependent on sailcloth flexibility and design exactly because they are not attached to a flexible/adjustable mast. Even more, if they have no battens.

Hopefully, both Dave Calvert and Arnaldo (author of the article) will go on with this thread. I can see that I'm just repeating the same reasoning... Sorry, this is already beyond the limits of my knowlege!

I want to know what this sail is composed of. Looks like a pure film windsurfer sail on a tboat.


When I get my tboat, I'm going to be looking for something like this. I think I'd like being able to see through my sail, it would make starting lines a lot safer imo.

It's probably a lot easier to fall THROUGH it in a capsize too....

Jake,

I'm disappointed, I thought you'd realize by now that rockstars like myself don't capsize.... evar :P

The object for most sailmakers is to come up with the best design, for a given boat, and use materials that will maintain this design over a wide wind range. There are two lifes for a sail,the life of the sail cloth, and the performance life. The performance life, is the length of time that a sail will matain its designed shape. The cloth life, is the time a given materal will last after being subjected to wind loads, flutter, UV exposure, etc.
In most cases, materals that have low stretch,light weight, and good durability are most prefered. There are always comprimises. The materials that best fit this discription, are also the most expensive.Sails made with low stretch materals, can be designed fuller. This gives more power in light winds, and will not stretch and become too full as the wind builds, compared to their more stretchy counterparts.Pentex is a good all around fiber for most beach cat sails. This fiber has twice the modulas as polyester, giving it twice the strength, and about 30% less stretch, as polyester. The price is also good. Using stronger cloth with less stretch, enables the sailmaker to go down in weight, as well. Jibs are often made with a preminum dacron called square dacron. This is a balenced weave and can be used in a triradial cut. This is a fairly low stretch dacron, and will stand up better to the abuse that jibs experance. The mains have many full battens that reduce flutter, they wear much better because of this. Laminates will last much longer in the full batten mains.
Dave

Some times wishes do come true…Thanks Dave for your informed comments. Never saw you post on Cat Sailor before…hope this is the first on many posts…it is so nice to have someone of your expertise take the time to respond.

I use to windsurf on occasionally with Tem Berkstresser, I remember him going incredibly fast on your racing sails, have you kept in contact with him?

Bob

Bob,
Thanks for the mention. It's good to hear from someone that remembers our windsurfer sails. That was a great period for me. Designing, and testing sailboard sails, resulted in some real performance breakthroughs. Alot of this has been applied to multihull sail designs. BTW, Tem Berkstresser just arrived at the loft yesterday. He is picking up a new Vectran screacher, and fullbatten jib for his 60' cat that he designed, and built.(with a little design help from Bill Roberts) It seems that most of the top US windsurfer sailors, and industry people are going to multihulls. Tem's ex partner Pat LeMahaute, is about to finish his 38' Kurt Hughes Tri,and Keith Notery's 60' cat is about done, as well. Many others are racing Corsairs, and beach cats.
Dave

Mr. Calvert,

Is there any information online about said 60' cats?

(pictures would be nice, my cubicle is very boring right now)

I still have one or two of your windsurf sails! I got out of the sport in the late 90's (too much $$ on the arms race) and picked up a beachcat. I guess I'm just one of the crowd! I still keep about 3 boards and a quiver in case I get the urge, though....

I figured my counterparts went to kitesailing with the expectation of bigger air. Being a true sailor at heart, I went "back", but couldn't handle going "slow" again, so beachcats were my only option (until I make gobs more money). Been on the F-boats, but not sure what to think of them yet. Need more crew time, I guess...

Keep up the great work down there, and congrats on your PlayStation accomplishments!

It is great to have you here!

I once bought one of your Hobie 21 square top mainsails (Giles delivered it to me personally) and that sail convinced other guys here to buy from you as well (SC17, SC19, etc.)

Unfortunatelly, so far I received no reply from Arnaldo, but (correct me if I am wrong) what you said is not in direct contradiction with what he said.

I think you said more or less that each sail cloth has its weight, moduli and durability features and the best sail is the one that, using those features, results in the best compromise. Then you gave examples.

Mainly, what Arnaldo said is the following:

a) rigid sails (I think he means those constructed with higher modulus cloth) are more secific to the wind strength they were designed for, then a more flexible sail.

b) Rigid sails (here I think he means 3DL and tape drive) do not keep their shape as long as it would be expected after they leave the mould.

Do you agree with those two statements?

THANKS!
Luiz

If your going square top, I would'nt use 5 oz Dacron, too stretchy. Pentex is the best option cost-wise. You might get a little preformance advantage using Kevlar of Carbon, but that small advantage will be short lived and probably not worth it unless you are buying sails to win the Nationals or something like that. The Pentex sails will be
a little more forgiving trim-wise, and that can be a good thing in chop.


Tell your sailmaker what kind of sailing you do and what
type of conditions you most often sail.

Good luck

I have a Calvert dacron square top for my 5.8. It must be 8 or 10 oz material - weighs a ton. I think the original owner must have asked for a sail that would outlive the boat. It goes like snot in light and medium air , but I have difficulty controling it in heavy air (15 mph +) - that might have more to do with me than the sail design though. In very light air it makes the boat almost unbeatable.

Luiz,
My feelings about "rigid" sails vs. "flexable" sails are this. Sail technolory has come a long way from the cross cut dacron days. The computer generated load maps of sails, has resulted in triradial cuts, 3DL,and tape drive sail constructions. All in an attempt to more acurately oriant the cloth fibers along the lines of stress, or loads on the sails. Materals have also gone from polyesters to Pentex, Kevlar, and more recently Carbon Fiber. All of this technology has resulted from the need to build sails that maintain their designed shape longer.
We build dacron sails only for durability and cost. Most of our customers are racers, and want the best performance for their money. We try to build the lowest stretch, lightest, most durabil sails for their budget. Sails that are "rigid"
and hold their shape over a wide wind range, are, in my mind the objective. We come up with the best design that we can for all conditions,and try to select a material that will maintain that shape. Most beach cats have numerous adjustments to alter the shape for differant winds. If we build sails from stretchy materal, the overall shape will be flatter to begin with, to account for the stretch, resulting from increased wind loads. There is more guess work involved.They tend to be too flat in light winds, or too full for high winds If the proper cloth is selected, the sails should maintain their designed shape for the life of the cloth. I don't know of many top racers, that are buying several sails, to meet the various wind conditions.
In fact most regattas restrict changing sails.
I hope this helps.
Dave

Dave,

Thanks again! I am not sure if I understand it all, but it makes sense to me.

I have excelent news:

The author of the article that started this discussion, Arnaldo Andrade, sailmaker in Cognac/Brasil (and also a physicist), sent me two replies, one of them quoting your words.

He wrote them fast after a day's work and asked me to edit, but I will just correct the typos. Some parts are marked "to be completed" and I will leave them as they are now.

[color:"red"]I will post both replies on his behalf as new replies to the initial post, so please go on with the discussion from there.[/color] I am sure that we will all benefit from the interchange of ideas.

Cheers,

b]The post Arnaldo is replying to:[/b]



Arnaldo's reply



Arnaldo Andrade is a sailmaker in Cognac/Brazil and also a physicist.

I disagree. There is no "best design" for a wide wind range. The more it is "best" the narrower is the wind range. A good example are Zuccoli sails for the Tornado Class, particularly the jibs. They are numbered and cover VERY LIMITED wind ranges. Zuccoly Dacron tri-radial sails still show some desirable geometric changes as the wind increases but their mylar counterparts are really good for their designed wind range, whis is generally a narrow one.

Sails that can be used in a wide wind range are precisely those that do change their shape, though very slightly and "in the right way" (that is, "self-flattening" in the breeze). Aided by important trim changes at the rig level, these sails can perform reasonably well ove a wider wind range.



I agree, the performance life of a Dacron sail, for instance, is usually 1/10 of its "mechanical" life.




The question is "why". It's dangerous to take for granted that only low stretch, light weight materials can make fast sails. In some cases, as for bigger multihulls, other factors become more important. Some self flattening ability, for instance, is highly desirable, since masts on these boats tend to be almost non-flexible.



This may be true for jibs but is not true for many mainsails. The Tornado mainsail, for instance, is cut almost totally flat, whatever the cloth used. It's the mast and the battens that give the sail its final shape. Although enormously successful, the Tornado mainsail is a blatant contradiction to the concept of the "preformed" sail.



This is true, particularly for beach cat mainsails.



Battened jibs (of Tornados' , for instance) can be made of Pentex, too. Other laminates, as the Brazilian Prolam, are made in a different way and resist in a better way the abuses that jibs experience.

Arnaldo Andrade
adrianno@openlink.com.br

Thank you Arnaldo,
Your comments reflect your vast experance with physics, and sailmaking.
I still dont understand why you would disagree on the concept of a "best" all around design, for a given boat.
We have gone thru extensive on the water testing for various class boats. Much like what we would do during our windsurfing sailmaking days.
We would try differant luff curves, twists, draft positions, etc. Than we would switch boats, and sailors, to eliminate variables, and often arrive at a shape that would best perform over a range of conditions. Granted, as wind, and sea conditions change, the shape of the sails should change as well.
But, most of our customers here, don't want to hear that they should be buying not one new main, but two or three to be more competitive in all conditions.
If the sail is very flat, (like the Tornado main that you mentioned)there will be a lack of power, in the light air.
This will result in the boat not being to fly a hull as quick as the competition. This is a disadvantage, like a windsurfer not being able to get on a plane as quick as other competitors. As the wind builds, the mast will bend from the added mainsheet loads alone. This will further flatten the sail, by taking out luff curve. If the mast bends as much, or more than the luff curve in the sail, the sail will distort, the draft will move aft, and performance will suffer.
For these same reasons, a fairly full sail, with stable sail cloth, will automatically self flatten as the mast bends under increased mainsheet loads. The modern downhauls can further flatten the main as needed. In fact we have been suscessful using the downhaul to flatten, and add twist to mainsails in light air, extending their range even further. Jibs, are another story. The jib adjustments are very limited. But again, most racers that we deal with, want one best suted to the local conditions.
You asked, "why" to my statement, "In most cases,materials that have low stretch, light weight, and good durability are most perfered".
Multihull sailors in general, go thru extremes to reduce weight, especally aloft. A light sail, reduces weight, and makes the boat easier to right. Most of the advances in racing sailcloth has been aimed at reducing weight, and stretch. From windsurfers, to America's cup, to the Maxi catamarns, this applies.
My question is, "how"
How can a flexable sail be self flattening on a large multihull, with a non-flexable mast? My experance has showed me that big multihull sails just keep getting fuller, as the wind builds, especally if the material is not stable enough, or the mast doesn't bend.
These are my opinions, based on personal experance with small to maxi multihulls.
Cheers,
Dave

Mr. Calvert,

Can your loft make me a sail like on that tornado that I posted earlier in this thread?

Yes,
We can, and have made cat sails out of monofilm. The Tornado main sail, in the photo, is probally a 6 or 7 mil monofilm.
We made a square top main like this for a Stiletto 23, about 10 years ago. The materal is low stretch in all directions but, not very durabil. I don't recomend it.
Dave

You're probably right. I don't have a very good history involving sail durability

Hi there,

(translated from Portuguese)

Luiz, please check if my answer is worth posting. I'd rather not start too serious a controversy - only healthy discussion. I'd really have no time for it and it is not without a certain sacrifice that I write those texts. Please use a spell checker in my replies because I have none in my computer. My English is rusty because most of the texts I've been writing lately are in French.

If you find anything too strong, please take it out.

Regards,
Arnaldo,

(end of translated text)




Dave Calvert’s paragraphs on the way he arrived to a best all around design are perfect. They help us in understanding that there is no basic contradiction between the quest for an “all around sail” and the creation of a sail with the ability to change its geometry. Such a sail would also be “an all around sail”. The difference is the following: whereas Dave’s way considers the sail geometry as essentially fixed and relies on the rigging for sail shape control; I believe that the sail itself can be part of the solution.

In his description he says:



A sail that could self flatten in the breeze would enlarge its useful range, possibly to a wider extent than could a “fixed geometry” type of sail (since the latter would rely only on rigging changes for shape control).

He then follows the thread by saying:



Whereas PHRF sailors may refrain from buying many different sails, a great number of classes indulge in a frenzy of specific sails. Tornado is one of these classes (especially for jibs), but even old designs as the Snipe do follow this trend - not that I agree with it. I'd rather keep sail inventory to a minimum. What I say is that nowadays many classes admit that a great number of sails may be necessary for a boat to be adequately competitive.

Then the question of the Tornado sail comes back:



First of all, a correction and an apology. I wrote that Zuccoli Tornado sails cover a very limited wind range. I was referring to the jibs. The mainsails do show a wide range of use, for reasons explained below.

In fact, if the Tornado sail I mentioned (99% of the boats use it) WERE flat, I would totally agree with Dave. It happens that a Zuccoli mainsail is NOT flat when set on the mast. It’s just its construction that is flat. The flying shape is not, due to the battens, to the mast and to a small number of almost secret details. The conclusions are far reaching, as they mean that you don’t need to put draft in a sail to see draft when the sail is properly set (*). Zuccoli mainsails are reasonably full in light winds and no one can deny they are a blatant success. But since they are (1) radial and (2) built flat, they respond much better to luff tension, outhaul tension and mast bend than previous sails. It was Dave himself who wrote:



What he is describing is - precisely - a sail that has variable geometry, that is, a self-flattening sail. The only mistake, in my opinion, is his reference to a “stable cloth”. Is is precisely because the sailcloth stretches that the sail geometry changes. The merit of Zuccoli and some other sailmakers, is to have devised a construction of sails in such a way that cloth flexibility is an aid in the control of sail shape, rather than an enemy to fight.



Keeping with the example of Zuccoli sails, it seems that the self-flattening ability of his mainsails could not be emulated on the jibs. The reasons may not fit in the present discussion, but the absence of an efficient way to tension the luff, together with incorrect cloth choice, may account for it. The fact is: one needs to have as much as four different Tornado jibs to work with a single mainsail. For me, this is a clear demonstration that these jibs could profit from a different approach, as construction techniques go. Of course the boats might also have to sport new trimming resources.

The subject than changed to low stretch and low weight:



Dave correctly states that low weight is always better and that is a sought-after characteristic in most sailboat classes. But my question was rather: why BOTH characteristics (lightness and low stretch) at the same time? I still think that a careful choice of sailcloth flexibility, with more stretch on the leach (for instance) may widen the useful range of the sails.

Then comes a new question:



I'd rather refrain from commenting on the exact details, but as you can certainly figure, building features like this into a sail requires a lot of skill and is a labor intensive task. Basically, one has to start by abandoning the pre-conceived idea that cloth flexibility is always bad. Once it is assumed that flexibility can be put to play in your team, instead of against you, the rest will follow - not necessarily in an easy way. But with a researcher’s mind and A LOT of experimentation and hard labor, one can eventually develop a consistent way to create self-flattening sails.

Remark: it may is interesting to note that also on the boats side some improvements are necessary. The powerful purchase on the luff tensioning system of the Tornados is one of these changes.

Cheers

Arnaldo

(*) I said above “you don’t need to put draft in a sail to see draft when the sail is properly set”. This is not new, of course. It has been known for about 3000 years. But the submission of human intelligence to sailmaking softwares is somehow erasing this information from the minds of otherwise well informed sailors.

Arnaldo

There is nothing illogical about wanting to have control over the shape/foil of your sail under as wide a range of conditions as possible. Just because the sail material has less stretch does not say the sail doesn’t move…the whole point is to control the movement…to have it attain and retain the designed shape…not just randomly respond to the conditions.

A hypothesis is one thing…real world sailing is a different proposition. When a sailor’s career lives and dies on his/her race results, they are going to use the fastest equipment they can get their hands on. Windsurfing has never been shy about taking on the most radical ideas and putting them to the test. If your design ideas are all that you purport them to be we should be seeing a shift to more flexible sail material in the future. Good luck. It sounds an awful lot like 1985 technology to me.

Personally I have been hard core windsurfing for 26 years, I have used all the different type sails that I spoke of earlier. There is no way you can equate a top of the line soft sail design that was popular when I started with a top of the line sail of today...been there done that!

I designed and built high performance sailboards (till about 2000) that hung in there with just about anyone’s with an equivalent rider. All my attention was on performance increases… board, fin, sails, masts, booms and the interaction between them, getting the feedback first hand...Bottom line is …The only thing that counts, is performance on the water…all the rest is just batting the breeze…regardless of who it comes from. Show me measurable advantage in real world conditions (against the industry standards) and then I will consider adopting your position.

Bob

Gee, Sharky, look what you started. I went back to your original question and noticed it doesn't say what kind of boat you sail.
Remember, on some boats (like mine) you can change the shape of your sail with enough downhaul to bend the mast. If you are using dacron, you have to be careful not to rip the sail in half with a 16:1 downhaul. It doesn't seem to be an issue with the Pentex. (yet) I just got new square-top Pentex sails for my P19. They're great.
My opinion is: Pick your sailmaker, then follow their suggestions on fabric.

Edited translation of Arnaldo's reply:



Cheers,

<<”Basically, sails with variable geometry require a good eye and active trimming. Many of the resources that my sails use wouldn't make sense in a windsurfer. This is the exact reason why windsurfers evolved into a system that modifies the sail shape more or less automatically.”

What I am beginning to see here is, this is as much a philosophy of what sailing entails, as it is a discussion of sail design. I see setting a preshaped sail with stiffer sail material, one, which automatically adjusts in the gusts and maintains its designed airfoil as a major advance and advantage to sailors who want to concentrate on maximum performance. Call it the KIS principal (if you add the second S you are making it too complicated). If major portions of sail trim can be automatic, that frees the sailor/sailors up to concentrate on other aspects of performance. It is not as if there are not enough duties in sailing fast to fill your time. It is in no way an autopilot. It just takes some of the variables out of the equation to bring the whole performance level up a notch or two across the board, it might help to close the gap a bit for those who are not “Rock Stars” of sailing. Heaven forbid… it might make it a little more enjoyable…

I cannot understand why sailing is always binding itself with artificial restraints. Some where along the line... the goal of building the fastest boat/sail took the back seat to self-imposed rules, and the fascination of making things more complex for no other reason than to make it more complex…as if doing things the hard way is something to be admired and embraced as “better” “more noble” or a sign of greater skill.

<<”This system, however optimal for windsurfers, doesn't seem to have real possibilities to work reliably in a bigger boat. The closer matches to be found here (and with many restrictions) are in the Moth or in the old Finn. But the manual trimming is not abandoned, even in this cases.”

Why not? Bigger boats? Most of the Cat Sailors on this forum sail boats that are between 14'-22'long. What are you including when you say trimming?
The windsurfer still sheets in and out…When he/she rakes the sail back and closes off the foot…isn’t that some what comparable to playing the main sheet line and the traveler? What about some of the racers using adjustable outhaul? Down Haul? How much more do you want tweak?
Don’t get me wrong…I don’t want to take away your lines to adjust this and that endlessly…if that’s where you get your joy far be it from me to rain on your parade.
Just a different philosophy…there is plenty of room for both approaches.

<<”That's why you are correct only with regards to windsurfers and not to bigger boats.”

<<”One detail: the technology does look with that of a 1985 windsurfer, but while windsurfers basically stopped there, we have evolved for another 20 years.”

I think it is just the opposite…Windsurfing has always been very tech driven…the rebel…the cutting edge…no rules…absolutely rabid about performance increases. Because of this mentality and the ability to crank out so many proto types due to the smaller size and lower cost (when compared to sails for most boats). In its hay day, Windsurfing Sail design was evolving so fast that a sail over a year old was no longer competitive, all other things being equal. In some cases the new sail designs were so much faster and controllable that a decent average short boarder could hang with, and sometime out run a more experienced rider (in a straight line) for no other reason than a superior sail design just one generation newer. Can you say that about Cat Sails year after year?

I would have to respectfully disagree with your statement that soft sails for boats have evolved for anther twenty years, while windsurfing stopped there. I would be more inclined to say that soft sails were one of the first stepping stones to be used by the windsurfing industry but they quickly evolved to more and more advanced rigs in an effort to satisfy the hunger for faster sails that covered a wider wind range and were more controllable/less tempermental.

Unlike "most" of the boat building community … which seems to say, “this is what you’re going to get and your going to like it!”

… Windsurfing was/is very consumer driven…and extremely responsive. A company would come out with a sail or board, and before it even hit the market they were finishing up the testing of the next generation, addressing as many issues as possible that the market brought to light. The improvements were/are amazing. And while many in the windsurfing community have defected to Kite Sailing, or moved on to other sports, to ignore the lessons learned in the accelerated R&D within the Windsurfing community would truly be a crime.

One interesting spin off from this discussion has been to remind me of Dave Calvert’s expertise in designing both Windsurfing sails (He was building some world class smoking fast race sails) and the Catamaran community…It puts him in a unique position, and the logical choice to go to when new sails are needed. (By the way I have never met Dave…but I do know his work…it speaks for itself…on the water…where it counts.)

Bob Hall

<<”Basically, sails with variable geometry require a good eye and active trimming. Many of the resources that my sails use wouldn't make sense in a windsurfer. This is the exact reason why windsurfers evolved into a system that modifies the sail shape more or less automatically.” What I am beginning to see here is, this is as much a philosophy of what sailing entails, as it is a discussion of sail design. I see setting a preshaped sail with stiffer sail material, one, which automatically adjusts in the gusts and maintains its designed airfoil as a major advance and advantage to sailors who want to concentrate on maximum performance. Call it the KIS principal (if you add the second S you are making it too complicated). If major portions of sail trim can be automatic, that frees the sailor/sailors up to concentrate on other aspects of performance. It is not as if there are not enough duties in sailing fast to fill your time. It is in no way an autopilot. It just takes some of the variables out of the equation to bring the whole performance level up a notch or two across the board, it might help to close the gap a bit for those who are not “Rock Stars” of sailing. Heaven forbid… it might make it a little more enjoyable… I cannot understand why sailing is always binding itself with artificial restraints. Some where along the line... the goal of building the fastest boat/sail took the back seat to self-imposed rules, and the fascination of making things more complex for no other reason than to make it more complex…as if doing things the hard way is something to be admired and embraced as “better” “more noble” or a sign of greater skill. <<”This system, however optimal for windsurfers, doesn't seem to have real possibilities to work reliably in a bigger boat. The closer matches to be found here (and with many restrictions) are in the Moth or in the old Finn. But the manual trimming is not abandoned, even in this cases.” Why not? Bigger boats? Most of the Cat Sailors on this forum sail boats that are between 14'-22'long. What are you including when you say trimming? The windsurfer still sheets in and out…When he/she rakes the sail back and closes off the foot…isn’t that some what comparable to playing the main sheet line and the traveler? What about some of the racers using adjustable outhaul? Down Haul? How much more do you want tweak? Don’t get me wrong…I don’t want to take away your lines to adjust this and that endlessly…if that’s where you get your joy far be it from me to rain on your parade. Just a different philosophy…there is plenty of room for both approaches. <<”That's why you are correct only with regards to windsurfers and not to bigger boats.” <<”One detail: the technology does look with that of a 1985 windsurfer, but while windsurfers basically stopped there, we have evolved for another 20 years.” I think it is just the opposite…Windsurfing has always been very tech driven…the rebel…the cutting edge…no rules…absolutely rabid about performance increases. Because of this mentality and the ability to crank out so many proto types due to the smaller size and lower cost (when compared to sails for most boats). In its hay day, Windsurfing Sail design was evolving so fast that a sail over a year old was no longer competitive, all other things being equal. In some cases the new sail designs were so much faster and controllable that a decent average short boarder could hang with, and sometime out run a more experienced rider (in a straight line) for no other reason than a superior sail design just one generation newer. Can you say that about Cat Sails year after year? I would have to respectfully disagree with your statement that soft sails for boats have evolved for anther twenty years, while windsurfing stopped there. I would be more inclined to say that soft sails were one of the first stepping stones to be used by the windsurfing industry but they quickly evolved to more and more advanced rigs in an effort to satisfy the hunger for faster sails that covered a wider wind range and were more controllable/less tempermental. Unlike "most" of the boat building community … which seems to say, “this is what you’re going to get and your going to like it!” … Windsurfing was/is very consumer driven…and extremely responsive. A company would come out with a sail or board, and before it even hit the market they were finishing up the testing of the next generation, addressing as many issues as possible that the market brought to light. The improvements were/are amazing. And while many in the windsurfing community have defected to Kite Sailing, or moved on to other sports, to ignore the lessons learned in the accelerated R&D within the Windsurfing community would truly be a crime. One interesting spin off from this discussion has been to remind me of Dave Calvert’s expertise in designing both Windsurfing sails (He was building some world class smoking fast race sails) and the Catamaran community…It puts him in a unique position, and the logical choice to go to when new sails are needed. (By the way I have never met Dave…but I do know his work…it speaks for itself…on the water…where it counts.) Bob Hall