WindFlyer said..
WARNING: more hands-on and facts-based commentary below.
duzzi said..
After five pages of posts frankly I am growing doubtful.
Weight? Weight saving is very hard to quantify, because we do not know the weight/m^2 of the material, and we can only compare manufacturers total weight. And that is unreliable and rather useless. All it takes is to use a thin mast base protector, or a different length and number of battens, or a thinner mast sleeve, and you change plus/minus 200 grams in places that have nothing to do with the material used in the sail.
not quite. i have two issues with your argument.
the first is the implied premise that it's all about the weight. i realise it's fashionable around here (and internet fora in general) to have a large dose of cynicism about brands and their marketing, but to imply that sailmakers are heavily compromising on critical components affecting stability (like batten choices and luff sleeve materials) to make a "lightest" claim is a bridge too far. no sailmaker i've ever talked to subscribes to that premise. certainly light weight is a design/construction objective, but one that is balanced against range and stability (performance objectives) and durability.
the second is the notion that the "material used in the sail" is uniform throughout. looking at any wave film/ply sail, it's quite evident that a variety of materials of various thicknesses and weights are used. looking at a "membrane" sail, it is also evident that the load bearing fibres are laid out in different densities in different parts of the sail. and looking at a 3Di sail against the light, one can also discern different layups of the materials in different parts of the sail. to summarise, the weight per surface unit of the materials are different throughout the sail.
so sail designers/makers try to balance the materials they use in the locations they need to meet their performance and durability objectives while trying to minimise weight. and batten and luff sleeve choices are critical element of this effort. so yeah, at the end of the day it is "the manufacturers total weight" that we're riding. as for quantification, reliability and usefulness, i'd offer these measured these data (from sails i had laying about):
* North Wave 3Di 4.7: 2.26kg
* Severne Blade Pro (membrane) 4.7: 2.97kg (~700g advantage to the North)
* Duotone SuperHero 4.7: 3.41kg (~1,150g advantage to the North)
[for kicks i looked up the specs of two other membrane sails, a hypothetical 4.7 SV S-1Pro (interpolated to 2.6kg) and a 4.7 Duotone SuperHero M (2.75kg), but as i don't have those available i didn't measure them].
with respect your comments on some details of construction:
* mast protector: the North mast protector is similar in feel to the Duotone, if a bit less extensive; both are more substantial in feel compared to the Severne
* battens: the number is a choice of the sailmaker to meet their objectives; but in all three cases rod battens are used (not sure whether some are glass or epoxy, but i may look into this just for fun).
* mast sleeve: the North has by far the thickest and stiffest luff sleeve of the lot (very obvious when trying to rig). it is clearly evident that the material allows North to build a beefy luff sleeve without incurring a weight penalty (particularly on a wet sail).
by the same token, it is apparent that the material allows North to make other weight-saving choices: for example, the leech of the sail above the boom is finished "cut" instead of having to have a band of stitched tape; the batten pockets are "built-in", etc.
duzzi said..
Performance? I just don't see why, or heard any reason why, a 4.7 3D sail, in which at least 1 square meter is regularly stitched window material, should be performing better than any other sail on the market. What exact advantage would the material give? Especially in a sail that is designed to de-power quickly, and for which stability in overpowered conditions is a secondary concern?
first, let's get some facts straight.
* the (measured) size of the window is nowhere near a square metre. it's actually not quite 0.6m (and nearly identical in size as that of the SV 4.7 Blade Pro, as membrane sails also have stitched windows).
* if stability in overpowered conditions was a secondary concern, then North failed miserably as the sail is incredibly stable in overpowered gusty conditions. i can't think of a wave or bump & jump sail that has been in the same league in terms of stability. (and yes, it does depower quickly too).
now for your question of what (performance) advantages would the material give. pretty much everyone i let try my membrane Blade Pros finds the feel of the material and weight of the sail to make it a "game changer". but hey, don't take my word for it, just read this quote from another poster in this same thread talking about them (emphasis mine):
SurferKris said..
I have a few of the Severne Blade Pro sails, 4.2, 4.7 and 5.3 from 2016. I bought them used in 2018 and these are the best wave sail I've ever had or tried. Yes, they are a little more sensitive/delicate compared to a thick monofilm sail, but it is well worth it. The cloth gives a little different feeling (compared to monofilm) and the low weight makes a big difference in marginal conditions. It has certainly changed my view of lightwind sailing in waves.
so, the (measured) weight of the North is lighter than the Blade Pro by about 2/3rds of a kilo, and the feel is both more direct and soft (and stable). where's the performance advantage? it's in what
YOU can do with that feel and weight differential (
SurferKris has said what it is for him in the case of the Blade Pros).
as i said, the feel is not easily described, but is best experienced. and as i also said, it's not for everyone, so it may very well not be for you.
duzzi said..
Cost? well, there the disadvantage is clear.
off the mark here.
there is no like for like product in the market now for an apples to apples comparison, so the costs have to be seen in perspective. and to do so i'll carry on with the three sails i've measured.
so for 2022 USD prices, i get:
4.7 Duotone SuperHero: 899 USD
4.7 North Wave 3Di: 999 USD
4.7 SV Blade Pro: 1,450 USD
let's also bring in the masts into the picture, using an EU-made 100% carbon mast across the board (Duotone 400 Platinum SLS $819, North 370 Skinny Pro $499, Severne 400 Red $810). that give us sail/mast prices of:
1,498 USD for the North combo
1,718 USD for the Duotone combo
2,260 USD for the Severne combo
sure, you can go for the North Ultimate mast ($669, or $270 extra) for top of the line performance. then at 1768 USD you're at a push with the Duotone (where you can also put down another $250 extra for a Platinum Aero mast)
so, i'm not seeing the clear disadvantage in cost to the North you mention. even in apples to oranges comparisons. if we were to say, for the sake of argument, that the North in feel/weight/performance is equal to or no better than a Blade Pro, it certainly has a significant cost advantage.
i'm sure there are other film/ply sail with their mast combos out there that can produce a lower overall price.
but as i said, the North is not for everyone.
