longer boom is proportionally inefficient if you are looking at
power plus manoeuvrability rather than power for a given
leverage the sailor can hold. With a lower aspect ratio you
can physically hold more power but we don´t need to go
full tilt on a wave board and you need proportionally more
area. With an higher aspect sail your stance is more upright
in a manoeuvre ready position and when you use the sail to
help manoeuvring, it has more effect as well. This is why
the Slayer has a higher centre of effort and the Karma has
it lower.
67
How long was it before you reached the
end point and a sail design you were
happy with?
What key points did you want to address
and why?
As I had been on one brand for +10 years, I had become to
appreciate their wind range. These sails have a lot of seam
shaping without batten rotation. This gives a lot of grunt in
super light winds and a stable shape in high winds. But you
can’t make the shape disappear, so on the wave it can’t
depower, it gives more drag and the rotation is quite hard.
Most other wave sails are pretty flat without wind and getting
their shape only from batten rotation, so you need more wind
to bend the battens to get shape. If you set a flat sail really
full (like in the photo above) the battens need to rotate a long
way around the mast, making it harder to flip the sail and the
sail becomes unstable. As a flat sail only gets its shape
stability from the batten profiling, they are overpowered
sooner as well. There was nothing in between really that uses
both seam shaping and batten rotation. Some brands do
have some seam shaping but only around 20% I was used to,
so there still is a surprisingly big gap in between.
So I was willing to sacrifice some of the wind range in favour
of handling and wave riding and we started reducing the
amount of seam shaping bit by bit. Going along I was
expecting to lose some low-end grunt but funny enough it did
not – on the contrary it was getting even a little better, which I
could not place at first. During the testing I was also videoing
the sails behaviour on the water from both sides to watch it
back in slow motion. It was when comparing with pictures of
my previous sails that I noticed that sails with a lot of seam
shaping do not have a smooth profile on the leeward side of
the sail, where the mast sleeve is attached to the sail – there
is a kink. The leeward side generates two thirds of a foil.
To increase the wind range even more, the seam shaping
we use is S-curved, locking the shape forward and we used
less outhaul tension to make the sail twist off more
harmonically, like most brands do.
The outline also became something in between, the foot
and clew cut up higher to have more clearance like various
known wave sails but with the slightly higher aspect ratio of
my previous brand. Wave sailing is not about top end speed
but to have the best combination between enough power to
be planing and a very good handling – for which a higher
aspect ratio is better. A sail gives lift by bending air and the
amount of air (luff length) that gets bend is more important
than for how long (boom length). Or in other words: You get
two thirds of the power from the first third of the sail so a
About three years and 30 prototype sails before we went to
the first production. More if you count the three batten proto
sails we made as well. They were working very well but simply
not as all round and durable as the four batten Slayer.
And in terms of hours testing; can you
put a number on that?
Hardly, no idea really, we just go sailing and don’t really see
that as ‘work’. Two years of testing between 5-7 people
would make like 2000+ hours?
How do WC sails differ from others?
As explained, for the amount of seam shape we are half-way
between my former brand and other brands. But from testing
the smaller sizes in Pozo and Sotavento, we found we did not
want too much power in the small sizes and having to rig even
smaller. Sail sizes can get too small too, you want to have
some size in your hands to work with, so we made the smaller
sizes increasingly less powerful and the 3.7 and 3.3 are
getting pretty flat with more batten rotation. In the end the
biggest size has about 60% of the seam shape of my previous
brand and the 3.7 and 3.3 just 25%. The amount of seam
shaping morphs through the range so to speak and basically
gives a bigger range than the numbers indicate.
Using both seam shaping and batten rotation gives the best
of both worlds, a big wind range, both natural and tuneable
still with a very smooth handling and rotation. It is easy to
find the right angle of attack and, as battens themselves
want to become straight, it is still easy to depower or rotate
the sail. You see some brands moving also into this
direction, which in a way is reassuring.
Any plans to tweak Karma or Slayer
design? If so, how?
At the moment we have been concentrating on reducing
weight whilst keeping durability. We were already using
symmetrical batten pockets and a kevlar reinforced frame
layout. By using very strong seam tapes we could now get
rid of the dacron seam reinforcement tapes and actually
end up stronger with greatly reduced seam creep. The top
two battens on all sails are now narrower to reduce weight
at the top, the Karma has a slightly thinner scrim in the
leach, and the Slayer now has a full 100% Dyneema mast
sleeve, which is not only three times as strong but also 40%
lighter. The sails are not the lightest out there but not the
heaviest either and for sure the most durable.
uk
WIND
SURFING