Especially in the top and towards the clew weight is key cause due to the leverage-effect you feel every gram a multiple times in your hands. Because of the quite limited amount of materials available though the only way to reduce the sail weight is by reducing the thickness of the materials. The secret is finding the sweet spot of lowest possible weight but without sacrificing durability and longevity/sustainability.
Modern Windsurf sails consist of the following raw materials:
(1) MAST SLEEVE MATERIAL
Rough woven Polyester fabric. The rough structure gives it a maximum abrasion resistance against impact from the outside (e.g. board contact or contact during rigging) as well as from the inside (through the mast).
Plastic film made out of Polyester available in clear- or colored versions. This hard plastic film has a very low stretch (for maximum performance) and doesn‘t absorb any water (dry weight = wet weight). Attention: monofilm isn't very UV-resistant. Therefore keep your sail out of direct sun light when not sailing. Also monofilm isn't very abrasion resistant.
(3) XPLY LAMINATE
2 thin layers of monofilm and a pattern of threads (out of Polyester or Dyneema) are glued together creating a sandwich laminate. The additional threads are supposed to function as a rip stop in case the film gets punctured (e.g. falling into the sail with your harness hook first). When using the same total thickness as monofilm (= same low stretch, same UV- and puncture-resistance) XPly is 30% heavier due to the additional adhesive (and threads).
Before discovering monofilm original Windsurf sails were made entirely out of Dacron. This woven fabric offers a very good abrasion resistance but is very stretchy plus elongates (means it grows with each use). Therefore nowadays mainly used for reinforcement patches to protect the monofilm and XPly panels in the high abrasion areas of your sail (foot, clew, top and outside of batten pockets).
Dacron material with a self-adhesive side. Therefore it doesn‘t require seams when put on top of the film plus prevents water from getting in-between the film and the abrasion patches (= lower wet weight).
Wanna know more details or looking for DUOTONE sail spare parts - here you go
Made out of glass- or carbon fiber either as solid version with smaller diameter (= stronger) or tube version with larger diameter (= stiffer). For a better understanding the mast is like the backbone of your sail whereas the battens act like the ribs of your sail keeping the profile in place. Same as the mast also the battens have individual profiles (thinner tip, thicker tail) matching the profile of the sail.
Simple rule: the more battens the more stable (= faster + bigger wind range) the sail becomes. But also the heavier the sail becomes as battens account for approx. 40% of the sails total weight. Therefore handling/wave-oriented sails usually come with 4-5 battens whereas performance oriented sails usually come with 6-7 battens.
As a second guideline smaller sail sizes require fewer battens than larger sizes.
Usually there is a certain gap between the batten tip and the mast. This is necessary so that the batten can shift from one side of the mast to the other when sailing back and forth. A camber can be seen as a kind of connection between the batten tip and the mast filling out this gap.
This leads to much better aerodynamics as the cam enables a smooth transition between the thick mast into the thin sail body. In addition since the cam is braced against the mast the batten stabilises the sails profile much more effectively (sail becomes more stable = faster).
The downside is that the rotation from one side to the other becomes much harder. Plus the cambers need a certain space which requires a wider mast sleeve. This makes (water)starting much harder as the wider mast sleeve absorbs more water. Therefore cambers are mainly used on performance Freeride or high-performance Slalom sails.
A sail with a lot of foot roach reduces the gap between the sail and the board (close the gap) which makes it more efficient/performance-oriented.
On the other hand a high cut foot with less foot roach improves the handling especially for all kind of ducking moves.
A deeper sail profile gives you more power and performance in general.
A flatter profile on the other hand improves the handling as the distance of the flat profile is much shorter when shifting from one side to the other.
BOOM- AND LUFF LENGTH
Together with the sail size all dimensions increase. Means in general the larger the sail the longer the boom- and luff lengths become.
Sail size vs. body weight
Simple rule: a heavier sailor needs to take a larger sail size to get planning in the same wind compared to a lightweight.
Rough indication for the biggest sail size: to get going in the same wind a 10 kg heavier guy requires a 1 sqm larger sail.
First you should define the biggest and smallest sail size you will need to cover all wind speeds you wanna sail in. This mainly depends on your body weight (see above).
Let’s take an “average” 75 kg sailor and let’s assume this guy wants to sail in “any kind” of wind.
- The biggest sail size this guy would need is something like a 7.3. With a capable 100-120 litre Freeride board this size would get him planning in approx. 8-10 knots.
- His smallest size would then be a 3.7. On a 70-80 litre (Free)Wave board our guy should be fine up to approx. 40-45 knots.
Second thing is to define the sizes in-between. Important to know: the wind pressure (which you feel in your hands) raises in square in relation to the wind speed. Therefore the smaller the sail size the smaller the size increments need to become. For large sails, the gap can be up to 1.5 sqm, while for very small sails it can go down to 0.3 sqm.
Taking all of this into account a typical quiver for our 75 kg guy could look as following:
7.3 - 6.0 - 5.3 - 4.7 - 4.2 - 3.7
Taking the “10 kg = 1 sqm” rule (see previous point) in consideration a typical quiver for an 85 kg guy could then be:
8.3 - 7.0 - 6.0 - 5-0 - 4.5 - 4.0
You have bought all parts from the same brand but if you rig according to the specs printed on the sail it still feels somehow ackward.
Unfortunately every product has tolerances in production. And the bigger a product becomes the bigger the tolerances become. Therefore tolerances on a smartphone are hardly visible whereas tolerances on Windsurf equipment are non-deniable.
- The tolerances on the mast length are approx. +-5 mm.
- The tolerances on mast extensions and booms are approx. +-3 mm.
Furthermore, there is unfortunately still no standard among brands on how to measure the length of booms and extensions.
- On a sail with all its panels the tolerances over the whole luff length can add up to another +-5-10 mm.
In addition, even with monofilm sails the luff stretches in the first 3 times you use the sail due to the massive downhaul tension.
Adding up all these tolerances you start realising why the absolute numbers printed on your sail (especially the luff length) can only be an indication to adjust your mast extension- and boom lengths.
To achieve the correct downhaul tension please make sure to only rely on the VTS (Visual Trim System) markers in the top of every DUOTONE sail.
Always keep in mind there are exactly 2 things either of them potentially killing at least 30% of your sails performance:
1. The wrong mast (see first point under MAST BASICS on every mast page)
2. Wrong/insufficient downhaul tension