Laminated sails vs Dacron durability

[wingssail]

Originally Posted by Dockhead

...
When you are sailing with the wind abaft the beam, it doesn't matter much, even in terms of knots -- because the sail is working by drag, not lift (primarily). The shape is less important than area in the wind...

Your whole post was filled with great explanation and info for the OP.

I would have two comments:

1. Sail shape is important for offwind work as well, especially head sails and flying sails. Our sails are acting as airfoils as deep as 150 degrees, even the jib or genoa. More modern boats, even more so. Many of the boats I sail on or against never have their sails in "drag mode". Their speed brings the wind forward and shape is important.
2. I cherish my carbon fibre membrane sails and their longevity seems to be good (but it's only been 5 years!) but I still get excellent use from my Dacron sails. My boat is 43', not so far removed from the typical cruising boat in size, and my 7 year old Dacron cruising main and my much older Dacron cruising genoa and working jib are still effective. My new Dacron heavy #3 jib is excellent and on the second year shows no sign of loosing its shape. Maybe the cut-off size for for Dacron sails is a bit larger.

People have the idea that Dacron sails turn into bags. Certainly a big Dacron genoa up in too much breeze can look pretty bad, but that's mostly because the sail is too big and cut wrong for the wind. Try a smaller sail. It won't look so bad and you go faster.

The price is a huge factor. I can put a full set of sails on a boat my size for about $10k. That's barely one sail of modern laminate construction. The laminate sails may be price effective, but for some folks, the initial investment puts them simply out of the question.

[Drek4]

Originally Posted by markiobe

A few things to add to the conversation when choosing sails; boat weight, hull type, sailing modes (sail size is also important but that's already been mentioned).

In theory the heavier the boat, all other things being equal, the more stress there is on the sails. Therefore Dacron sails would likely last less time, through stretch, and the argument for some kind of film (as opposed to woven cloth such as Dacron) sails makes more sense.

A similar argument applies to catamaran vs monohull; the ability of a monohull to heel reduces the 'impact' loading of a gust and therefore reduces the stress on the sails. Although catamarans are typically lighter than monohulls, given that they don't heel much to ease the pressure there's a pretty good argument to make, especially for heavy 'cruising' ones, that film sails make more sense as they undergo a huge amount of loading. If you also have bluff hulls (very likely in the heavier cats) then the force required to drive the hull through the water goes up, again increasing the stress on the sails.

Add these 2 points together and you end up with the somewhat counter-intuitive argument that for heavier, cruising boats, film sails make MORE sense than for lighter, more performance-orientated boats. Add to the fact that heavier boats need bigger sails and the argument makes even more sense.

Sailing modes; the more upwind sailing you do the more the argument for film sails makes sense. The further forward the apparent wind, the larger the force on the sails for a given wind strength. Efficient sailing upwind is more dependent on good sail shape than downwind (at least from a cruising perspective) and given that you're choosing to sail upwind, your destination is going to be hard to get to anyway, therefore efficiency is both desirable and sometimes safer.

Personally I am sailing and I want to sail efficiently. It makes my eyes bleed to see so many cruising boats with horrifyingly stretched sail shapes with the owners wondering why they can't go upwind, they sail slowly etc. etc. Add to that the number of poorly trimmed sails whose owners clearly have no understanding of twist, slot etc then maybe having old Dacron sails is fine for most as they clearly aren't interested in sailing efficiently anyway? Is that too harsh...?

Thank you very much for your input, very informative.
It will be a monohull, between 34 to 39 feet, most likely towards the lighter side.

[Drek4]

Originally Posted by arobbert

I have had laminated (Norlam) sails on my boat for the past 11 years. They are still in great shape, but after the first year they began to develop mildew stains due to moisture retained between the laminates and it got steadily worse. They are definitely dingy-looking.

Thank you for sharing this, didn't know that it could breed mold between the layers.

[Drek4]

Originally Posted by Dockhead

The difference between a sail with good shape and a sail with bad shape is not primarily measured in knots.


When you are sailing with the wind abaft the beam, it doesn't matter much, even in terms of knots -- because the sail is working by drag, not lift (primarily). The shape is less important than area in the wind.


But when you are sailing upwind, the sail has to become a wing -- it moves you with lift, not drag, and drag is the enemy. That's where the art of sailing becomes interesting, shaping and angling the sail to make it work like a wing, maximizing lift vs. drag, getting the angle of attack right. A blown-out dacron sail cannot be trimmed much; can't be made into much of a wing. It's not only slower, it's much less fun to use. You have much less control and much less you can do with it. You can't make it flat and you can't control the draft. You heel much more and have to reef much earlier and can't sail nearly as close to the wind.


That's not measured in knots, that's measured in sailing pleasure. This is more or less important to different people. If you don't care that much about sailing, as many cruisers don't, and that's perfectly fine -- the sport means different things to different people -- then don't worry about the sails, and just use the motor when you can't make decent progress upwind. That's the way my father ran his boat, with old Dacron sails, and we had an enormous amount of fun (even if we put a lot of hours on the old 4-108).


But if you like to sail for sailing's sake, then you may not find Dacron sails satisfactory, at least not on a larger boat. As someone mentioned above, the stress on the sails goes up geometrically with the size of the sails. Somewhere over 40 feet, I think woven sails are pretty hopeless for keen sailing, even cruising, and certainly over 50 feet. Under 30 feet, it doesn't matter nearly as much and good Dacron sails can give good results.






That's old information. There was a revolution some years ago with the process for making laminate sails -- they starting cooking them in autoclaves. This immensely increases the resistance to both mildew and delamination.



When I had carbon laminate sails made for my boat in 2015, 7 years ago, I didn't expect them to last more than 4 or 5 years, but I didn't care, because I love to sail and was sick of stretchy woven sails which I couldn't trim properly. The sailmaker told me that the new laminate cloths were extremely durable, totally different from the older ones, and if you order with taffeta on both sides (which is too heavy for best racing performance), I could expect 10+ years and 20 000+ miles. I didn't believe him!


But lo and behold, 7 years down the pike and 20 000+ miles later, miles in very harsh conditions sailing to Northern Greenland, to Iceland, back and forth across the whole Baltic, most of the European Atlantic coasts, and a dozen times across the North Sea, in all kinds of weather, with the sails always up since I sail year round, and in a wet climate to boot, there is not a spot of mildew and no delamination. There's a bit of chafe now, a bit of algae around the sun strips, and I'm sending them to a sailmaker for cleaning and a bit of work (for the first time!), but the shape is like new and I don't see any signs that they are getting tired or nearing end of life. My guess is this is about half the life, and I would be surprised if I get only 10 years out of them. I did a long distance ocean race last year and finished very well, with these very well used sails, which from any distance still look like new.


So 3 years? That might be for string sails, or very thin racing laminate sails. Cruising laminate sails protected with taffeta on both sides (Dyneema taffeta in my case) and laid up in an autoclave are incredibly durable, much more so than Dacron. They are not cheap, admittedly, but per mile I would say not much more expensive than really good Dacron like Marblehead. And per mile with good shape incomparably cheaper.

Thank you very much for your detailed and very informative input.
So it's not a great idea to keep deformed sails, since performance up wind is heavily impeded.
The sailboat that most likely will be purchased will be between 34 to 39 feet, monohull and most likely towards the lighter side, so I guess a good Dacron like Marblehead would be the best economical choice for me.

[Drek4]

Originally Posted by wingssail

Your whole post was filled with great explanation and info for the OP.

I would have two comments:

1. Sail shape is important for offwind work as well, especially head sails and flying sails. Our sails are acting as airfoils as deep as 150 degrees, even the jib or genoa. More modern boats, even more so. Many of the boats I sail on or against never have their sails in "drag mode". Their speed brings the wind forward and shape is important.
2. I cherish my carbon fibre membrane sails and their longevity seems to be good (but it's only been 5 years!) but I still get excellent use from my Dacron sails. My boat is 43', not so far removed from the typical cruising boat in size, and my 7 year old Dacron cruising main and my much older Dacron cruising genoa and working jib are still effective. My new Dacron heavy #3 jib is excellent and on the second year shows no sign of loosing its shape. Maybe the cut-off size for for Dacron sails is a bit larger.

People have the idea that Dacron sails turn into bags. Certainly a big Dacron genoa up in too much breeze can look pretty bad, but that's mostly because the sail is too big and cut wrong for the wind. Try a smaller sail. It won't look so bad and you go faster.

The price is a huge factor. I can put a full set of sails on a boat my size for about $10k. That's barely one sail of modern laminate construction. The laminate sails may be price effective, but for some folks, the initial investment puts them simply out of the question.

Thank you for your informative reply.
Cost is a factor that is very important for me also.

[Dockhead]

Originally Posted by Drek4

Thank you very much for your detailed and very informative input.
So it's not a great idea to keep deformed sails, since performance up wind is heavily impeded.
The sailboat that most likely will be purchased will be between 34 to 39 feet, monohull and most likely towards the lighter side, so I guess a good Dacron like Marblehead would be the best economical choice for me.

Sure. I would shop around, though, and keep an open mind.



That size boat good Dacron will probably be ok, but cruising lam might not be that much more expensive.


Also, what kind of main do you think you will have? I would not recommend in-mast furling on a smaller boat like that, but if you do end up with in-mast furling, then you will really want laminate sails, because the furling mechanism is much more reliable and functions much better with them.


Also, I wouldn't be in a hurry to change the sails -- I would give yourself a year at least to learn the boat and get used to it, before you put on new sails. Inevitably you will flog the sails and make some other mistakes -- as we all did -- and you will want that abuse to happen to sails you are about to get rid of, not sails you just acquired.

[Drek4]

Originally Posted by Dockhead

Sure. I would shop around, though, and keep an open mind.



That size boat good Dacron will probably be ok, but cruising lam might not be that much more expensive.


Also, what kind of main do you think you will have? I would not recommend in-mast furling on a smaller boat like that, but if you do end up with in-mast furling, then you will really want laminate sails, because the furling mechanism is much more reliable and functions much better with them.


Also, I wouldn't be in a hurry to change the sails -- I would give yourself a year at least to learn the boat and get used to it, before you put on new sails. Inevitably you will flog the sails and make some other mistakes -- as we all did -- and you will want that abuse to happen to sails you are about to get rid of, not sails you just acquired.

Thank you for another informative reply.
I didn't know that the furling system works better with laminate, very good to know this.
Yes will certainly "practice" with the existing sails, most likely mistakes will be numerous, the first and maybe second year also.

[wingssail]

Originally Posted by markiobe

A few things to add to the conversation when choosing sails; boat weight, hull type, sailing modes (sail size is also important but that's already been mentioned).

In theory the heavier the boat, all other things being equal, the more stress there is on the sails. Therefore Dacron sails would likely last less time, through stretch, and the argument for some kind of film (as opposed to woven cloth such as Dacron) sails makes more sense...

The fact is that all sails are designed and built with cloth weight and strength appropriate for the weight and size of the boat and the wind force expected.

A heavier boat will have heavier (stronger) cloth, Dacron or Laminate, for its sails so the theory that Dacron would stretch more is not necessarily true. For the heavier boat stronger Dacron will be used.

The difference is that heavy Dacron is really heavy. The same strength can be obtained in a good laminate at half the weight, and it will go longer without losing its shape. My 110% Dacron #3 jib is 9.5oz cloth and weighs a ton, and is only used in winds over 16kts true (22 apparent), but in two years it has not changed shape at all. It cost me $1100.

[Drek4]

Originally Posted by wingssail

The fact is that all sails are designed and built with cloth weight and strength appropriate for the weight and size of the boat and the wind force expected.

A heavier boat will have heavier (stronger) cloth, Dacron or Laminate, for its sails so the theory that Dacron would stretch more is not necessarily true. For the heavier boat stronger Dacron will be used.

The difference is that heavy Dacron is really heavy. The same strength can be obtained in a good laminate at half the weight, and it will go longer without losing its shape. My 110% Dacron #3 jib is 9.5oz cloth and weighs a ton, and is only used in winds over 16kts true (22 apparent), but in two years it has not changed shape at all. It cost me $1100.

Thank you for your input and interesting information.
If the sails for powerful winds are so much more heavier than normal sails, could this affect the stability of the sailboat?
Never thought there was such a huge choice of sails.

[Jammer]

Many excellent posts upthread.


A fact not mentioned is that some sailors believe that laminate sails are a particularly good match on boats with in-mast roller furled mains. They are thought to be less prone to jamming.

[Drek4]

Originally Posted by Jammer

Many excellent posts upthread.


A fact not mentioned is that some sailors believe that laminate sails are a particularly good match on boats with in-mast roller furled mains. They are thought to be less prone to jamming.

Thank you for your reply.
Looks like Laminated sails do have an advantage with furling systems.

[wingssail]

Originally Posted by Drek4

Thank you for your input and interesting information.
If the sails for powerful winds are so much more heavier than normal sails, could this affect the stability of the sailboat?
Never thought there was such a huge choice of sails.

Absolutely! Weight aloft is detrimental to stability. It was this characteristic of laminated sails (more than their shape holding ability) which led to laminated sails being developed in the first place. Otherwise top end racing boats could simply buy a new (heavy) Dacron sail every few months, replacing them before the shape changes, and probably save money.

But for all boats, racers most of all, light weight is worth the premium.

[markiobe]

Originally Posted by Drek4

Thank you for your input and interesting information.
If the sails for powerful winds are so much more heavier than normal sails, could this affect the stability of the sailboat?
Never thought there was such a huge choice of sails.

Short answer: yes.

Longer answer: there is no situation where weight up high is a good thing. One of the advantages to laminate/film sails is they are typically lighter for a given size than a woven cloth. This gives significant sailing advantages as well as making them easier to handle. This is not just for racing, less weight up high will reduce heeling moment and reduce hobby-horsing, both of which are relevant to cruising sailors! This issue is the reason why hydranet is only a kind of halfway house, it keeps its shape much better than Dacron but is really heavy.

Weight up high is also the main reason for carbon masts and dyneema standing rigging. Racing boats (where the class rules allow) will go to the trouble of tapering halyards so that the line is as thin as possible up high and only thicker where they are going through cleats/clutches etc.

[pjShap]

A simple example of elevated weight: Removing 100 pounds centered 30 feet above the deck is equivalent to putting 500 pounds on the rail of a 12-foot beam (rail is 6 feet out from the centerline).

[Adelie]

Originally Posted by wingssail

Absolutely! Weight aloft is detrimental to stability. It was this characteristic of laminated sails (more than their shape holding ability) which led to laminated sails being developed in the first place. Otherwise top end racing boats could simply buy a new (heavy) Dacron sail every few months, replacing them before the shape changes, and probably save money.

But for all boats, racers most of all, light weight is worth the premium.

Reducing weight aloft is great for racing it allows a boat to reef a little later than competitors and maintain a slightly higher speed a little longer. But the OP is cruising.

One could argue that the speed advantage might be a safety consideration but let’s say you consistently gain 0.1kt (probably an overstatement but let’s be generous), that’s 2.4nm/day which not really enough to outrun bad weather unless you were already close to a protected harbor.

But then you might argue that the reduced weight aloft increases stability is a safety advantage because it increases capsize resistance in breaking waves but that’s WRONG.
Following the 1979 Fastnet race research showed that sailboats without mast had vastly more stability, had a greater Angle of Vanishing Stability and were much more susceptible to capsize. Blew everybody’s minds, highly counter intuitive.

Ultimately they realized that stability is a static phenomenon (even when the boat is moving) and capsize is a dynamic phenomenon and roll moment of inertia is a primary consideration. Turns out that the mast contributes about 50% of the roll inertia despite only being 2-5% of the mass.

In this case the weight of the sails should not affect capsize resistance either way because by the time you are in survival conditions with breaking waves you should have regular sails secured with storm sails up.

It falls on the OP to decide if the marginal gain in speed is worth the added cost.