savageseadog
Well-Known Member
There are in fact hundreds.
Laminate sails v conventional dacron
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There are in fact hundreds.
r_h
Well-Known Member
Last season we did roughly 4,000 miles on Zest (36ft, 5000kg) including a round trip to the Azores; max wind approx 40 knots.
The OneSails double taffeta laminate blade jib is still almost indistinguishable from new.
The Elvstrom main of a similar spec which dates from 2007 (but was little used in the previous ownership) is showing some wear, but still looks to have a considerable life ahead of it -- good enough that we plan to use it for this year's two-handed round Britain and Ireland Race -- overall we'll probably put a similar mileage on the sails this season as we did last year.
Having said that, we are very careful to look after the sails well, avoiding flogging, fluttering leeches etc and reefing in good time.
As others have said, the choice is down to your priorities - if you will always motor sail to windward with a mainsail often flogging, then a laminate sail will be a waste of money. Equally, for 3,000 miles of downwind work in the trade winds I'd just use old Dacron sails and save the decent ones for times that they will make a bigger difference.
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estarzinger
Well-Known Member
Realize that most all laminate cloth is built on a film layer(s) (PET or PEN, like "mylar" brand for example). That film is more sensitive to both flutter and to UV than dacron fibers are. That is common across most laminate cloth. The most common failure mode is the film fails rather than the fiber fails - this tends to happen either along a leach " flutter riser' or where the film gets crushed under the reef clew points.
I may have missed it, but I did not notice in the thread the two main differences between woven dacron and laminate dacron. First, woven sails are (typically) made in cross cut designs (except a few warp oriented fabrics), which laminates are almost all made in radial design. The Radial design better orients the fibers to the loads, but causes significant extra waste and labor and more transitions (which may or may not age poorly depending on how well the sail is designed and constructed)
Second, woven cloth is pretty strong and low stretch (just dependent on the fiber properties) in the 0 and 90 directions but will stretch along the 45 degree direction. There are two ways to reduce this. The better way is with a tighter weave. The less good (but cheaper) way is by adding resin fillers to the cloth. This resin helps when they the sails are new, but falls out of time/use. Hood used to make the best tightest weave in the industry on some looms they had in Ireland that were originally designed to make very high count cotton sheets and pillow cases. These looms were very slow (and thus somewhat uneconomical) but made terrific cloth. If you look at the Vektran test results you will see that the cloth scores quite high, but if you look at the results closely you can see it is because of the wonderful weave and the Vektran is doing almost nothing. Laminates reduce the 45 degree stretch because the film is isotropic (equally strong in all directions), so laminates typically rely on the film strength for the bias stretch and because the sails are radial they can then put more fibers on the 0 direction. Thus they are stronger and lower stretch for the same weight. But, as I mentioned just above, the film becomes the most typical failure point.
North Sails (relatively) new 3di cloth is (one of) the first to create a 'laminate like' sail but do away with the film. They build the sail basically with pre-preg carbon fiber (and other fibers) tapes that jut glue to each other rather than to a film base. This has turned out to be a bit heavier than a film base sail but does not have the film weakness. It is expensive and feels crappy (like poly tarp) but performs well.
KellysEye
Well-Known Member
> Hood used to make the best tightest weave in the industry on some looms they had in Ireland that were originally designed to make very high count cotton sheets and pillow cases. These looms were very slow (and thus somewhat uneconomical) but made terrific cloth.
Agree. We bought Hood after getting different cloth samples and putting a bright light behind the cloth and looking at it through a magnifying glass. The amount of fibre to glue was way ahead of any other cloth. There was no stretch after 10,000 miles a mere day sail to you and Beth ;-)
Agree. We bought Hood after getting different cloth samples and putting a bright light behind the cloth and looking at it through a magnifying glass. The amount of fibre to glue was way ahead of any other cloth. There was no stretch after 10,000 miles a mere day sail to you and Beth ;-)
TradewindSailor
Well-Known Member
I've just had a quote from North for a cruising genoa. They gave me samples of NorDac Radian 8.1 (Dacron), NorLam 7.0 XW, and NorLam SRP65. The salesman discounted both laminates as they had a propensity to discolour due to mildew although he said that they would hold their shape longer, but their overall life would be shorter than Dacron.
I'll shop around a little more .......
I'll shop around a little more .......
Robin
Well-Known Member
=snooks;4617669]The ideal compromise is Hydranet. Not that it's a compromise at all
Dacron longevity with the non-stretch properties of laminates. Only downside is the cost.
Back to the OP. Cruising laminates retain their shape longer, but last around 8 years. Dacron could last twice as long, it can be recut when it goes out of shape. But as soon as they are put up they start to stretch and it's an irreversible process. The more you sail in stronger winds the more they stretch. The more you leave them under tension (boom out haul and genoa halyard), the more they stretch. As Dacron stretches the draught of the sails increases. In gusts the draft increases more (from fore aft stretch and top to bottom- made worse with stretchy halyards) so the boat heels more and you slow down. Cruising laminates don't stretch, and to make the most of it you'll need low-stretch halyards, something like dyneema.
So as a rough guess after around 3 years bog standard Dacron sails would lose to laminates, and go down hill from there.
It's also worth pointing out there are many different grades of Dacron, from the OEM sails that are as cheap as chips so the mfg can honestly say a "sail away price" to high performance variants, a tighter weave with a hight thread count and weight, some with thicker threads, or in the case of Hydranet, dyneema threads interwoven into the fabric.
+1 from the other serious fan of Hydranet. Even our nice new in-mast main is Hydranet, made by Crusader in Poole and shipped to us in the USA in just 4 weeks, thanks guys!
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Amulet
Well-Known Member
I do not believe that is the case. The barrier is the sharp increment in energy associated with wave generation when you reach the speed where you have to climb up your own bow wave to go faster, not skin friction. All of the improvements suggested will improve performance when conditions don't allow you to reach hull speed, and will diminish the power required to reach hull speed, but you still face the same discontinuity in energy required - to go faster you have to plane or wave-pierce. (You do get transient bursts of speed in surfing a following sea, but I'd say they are not a sustained feature of cruising sailing - unless you cruise a lot more energetically than me!)
onesea
Well-Known Member
Not arguing with the physics, modern boats (particularly light racing boats) produce less bow wave create less of a trough so have less of a bow wave to climb up. They can also have more efficient lighter rigs with more righting ability for less given weight. On a modern light weight boat I do not believe the barrier is as sharp as it used to be. This gives more ability for occasional busts of rule breaking speeds, modern boats certainly do this more readily faster and for longer periods than older boats.
You just need to see modern boats racing to see that its not that unusual to break the rule, its happening more frequently faster and for longer periods. Modern sails and modern design lighter cruising boats mean that this is gradually becoming in reach of cruising folk (Pogo 10.5 etc).
Amulet
Well-Known Member
Yeah, I think you're right - effectively almost coming on to the plane I think - even some of the big beasts I was watching in the Sydney Hobart, where they were hitting 25-30 knots in patches. It seems to me to be pretty edgy stuff, but I'm an old geezer and happy to plod along at displacement speed.
srah1953
Well-Known Member
But they are "not breaking the rule". They are planing, like a dinghy. Pogo's are built to plane, lightweight with a very broad stern. Otherwise the "rule" still holds. Unless a boat is built to plane it is stuck with the displacement limits, except, obviously, when it's surfing.
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grumpy_o_g
Well-Known Member
1.34 x root of LWL is not a rule, it's just an oft used figure that fits many traditional displacement hulls. The other extreme is a multihull with it's very fine bow entry and big LWL to wetted beam ratio - you can replace the 1.34 with 2.34 (or more) on a fast cat design. Designs with long counter sterns such as the Spirits Yachts increase their waterline length when they heel so they often "cheat" the formula too.
Having a design that has a hull speed of say 1.6 x root LWL doesn't mean that you will be able to reach hull speed with same amount off power that another design needs to reach it's lower hull speed either so a faster design may well need a bigger or more powerful rig to actually go faster (so I'm told).
Having a design that has a hull speed of say 1.6 x root LWL doesn't mean that you will be able to reach hull speed with same amount off power that another design needs to reach it's lower hull speed either so a faster design may well need a bigger or more powerful rig to actually go faster (so I'm told).
Jamesuk
Well-Known Member
Dacron or EPEX nothing in between is worth it
Amulet
Well-Known Member
I thought the speed at which you end up stuck behind your bow wave was an invariable function of LWL - could be wrong. You can break through the barrier by planing or wave piercing. My understanding is that cats with narrow hulls can cut through the bow wave rather than climbing it. I have read that this effect kicks in at waterline beam less than 1/11 or 1/12 of waterline length, though where that magic number comes from beats me.
Don't think it breaks the rule, just changes the lwl to up the hull speed.
Is this actually possible? I didn't know it was, but have to admit I don't understand the origin of the 1.34 magic number. I thought it was an immutable consequence of lwl and speed, and that planing or wave piercing were your only barrier breaking options. (Not trying to be a smartass, just trying to understand, and glad to be corrected.)
