Testing, Testing

Testing is off course essential for the development of equipment. First of all you need to go out sailing to get new ideas. And these new ideas will also have to be tested properly before they are sold to customers. But there can be big differences how, what, where and who does the testing.

For testing new products, you have various stages. Many products can be tested in laboratory conditions, which give the best and very accurate comparisons. Testing in windsurfing can be very difficult as the conditions we encounter are always changing. Having laboratory like conditions are very useful, especially for testing new designs. The use of CFD (Computer Fluid Dynamics) have indeed given us this possibility. By simulating various critical situations in wave sailing, we can learn a lot about board lift and drag and fin lift and drag. Results come much quicker and far more accurate than you could ever realise even after years of testing in reality. CFD does not only give you lots of data on lift and drag of the board and each individual fin but it can also recommend what to improve. Still, despite all these possibilities, CFD is hardly used in windsurfing, only for slalom fins or foils, which are much easier as the effect of the board or water surface is not taken into account. We at Witchcraft have taken into account the effects of the water surface, the effects that a board is partly in water, partly in air and the effects of the board to the water flow underneath. We have also been filming under water to compare the flow with the CFD results.

As far as I know, no other brand has done anything like this ever. None of the bigger brands with a much bigger budget. Anyone who has tried our fins know that it certainly has paid off.

Then having laboratory like real life conditions is very useful to double check the CFD results. For stuff like lift, drag, grip, tight turning, keeping speed, the best is to have clean light wind conditions in such conditions a good sailor who is pushing, feels even small changes. The North Shore of Fuerteventura is known for its clean and predictable waves and at times perfect float n ride conditions unlike pretty much any location in the world. For this kind of testing it is also important to have very skilled riders who can reproduce the same turns over and over again and feel very well what the equipment is doing.

And for each comparison, it is essential to be changing just one parameter at a time. You hear sometimes riders say: “I tested fins with toe-in but they did not work”. So I said, these fins, did they just have toe-in or also have an asymmetrical profile? “Both.” So how do you know it is the toe-in or the asymmetrical profile? Any hydrodynamic expert can tell you that when you change the asymmetry of a fin profile this has an influence on the angle of attack and you need to add more toe-in than for a symmetrical fin. CFD also shows this. There is a lot more going on below a wave board than what you´d think. You even see surf fin manufacturers and/or universities, who spend a good bit of cash on research, testing just the fin in a water tunnel, without a board attached, thus not taking the effects of the board to the water flow underneath into account, so straight away you can throw all your results in the bin as the fin will behave differently when mounted under a board. Quite essential I´d say.

After this kind of important exploring research, you get into the more real world testing. A big argument by the “big” (big is relative these days) brands and their customers is always that their products are tested by pros and in the PWA. But is this really representative for end users? Pros who sail all over the world usually there where it is windy in that period and who have a far bigger quiver than most end users. Boards for on shore or side shore, for light, medium and strong wind, for jumping or riding. Sometimes even light boards for competing.
If boards, developed by pros, were so thoroughly tested, should they not look a lot more similar? How often have we not seen new models appearing on the market with a lot of hype but then being discounted by 50% after 6 months and disappear the next year?

The Formula 1 circus is a big comercial circus in a way. But there are things they do which eventually have benefitted the every day cars you can buy. By giving penalties for each time a team needs to change an engine or other parts, they force competitors to become more durable, by limiting the amount of fuel to be used they improve environmentally friendlier engines.

So if the PWA would take an example from F1, and, for example, allow for a 3 month period to experiment with a variety of equipment but then during the whole competition season put a maximum of say 2 boards and 5 sails to be used, both for competing and training. Then, like in F1, if a board change is wanted or needed, this would cost the rider points, then it would be a lot more similar to how end users use their equipment. This would give a great boost to development which would actually be beneficial for end users: more durable, environmentally friendly equipment with a bigger range.

Now that there is no PWA this year, I get the impression more people are starting to see there is more than the PWA and the brands involved.
I would say this would be a good opportunity to reset the PWA, to change these rules for the benefit of the future. And such a set up would certainly be a lot more interesting for Witchcraft to join in. But I doubt they will even consider this. The PWA is more a marketing tool for them than a way to actually improve development.

In Slalom sailing, is the end user a fully muscle packed pro, who sails full power with a heartbeat of 180 just for 10 mins? Sailing just down wind legs of a few hundred of meters and each time having to jibe and accelerate again? No, far from that. But with the pros being forced to use production equipment, equipment ends up being tuned for the pros and not the end user. Nowadays with GPS any sailor can compare their speed with others on the beach, swap boards and try again.

Another problem such brands face is the delay in feedback from end users. The usual process is that a new shape needs to be handed in by the end of December. After that, moulds are made and first samples are made to be tested. Then when everything is approved, production needs to start to be able to deliver new models in shops in August. From then, the first end users (often national team riders or fan boys) who bought them only have a short time left to deliver feedback and let that flow into the new models. This period is far too short for any thoroughly testing. Magazine tests will usually not appear till spring and in the end do not count. No matters what magazines say in their tests (if they say anything meaningfull at all), it is the end user that counts.

Custom brands usually have a much more direct contact with their customers. Especially if they are based in locations with a high frequency and wide variety of conditions, there will be locals with a high skill level as well as with a medium or lower skill levels but who just love to windsurf. And the shaper and workers at the factory will also be able to test their own creations frequently. And these locations will have many locals who especially moved there to live for windsurfing. And will be a known windsurfing holiday destination where visitors also provide feedback, even if it were just to see how other equipment works and lasts. Frequently having to do repairs on other brands stuff can also be informative, even if it is just to see what doesn´t work……

But you also see custom factories appearing in places far from frequent and a variety of conditions. With all respect but if you are a keen windsurfer and an ambitious shaper or sailmaker, would you not want to move to a location where you can test frequently in a wide variety of conditions? One of the benefits of the EU is to be able to move materials and people to such locations. But you still can´t transport good windsurf conditions elsewhere…..even less to the middle of Europe.
And it simply is a lot more fun too to live somewhere like that rather than being stuck somewhere hours away from some infrequent mediocre conditions. And without being able to test frequently and thoroughly, development can only happen at a fraction of the speed. With the only other option left is to try to copy what you can but this means you will always be running behind without even really having a clue whether it is good or bad what you are trying to copy. It would not be the first time that brands, desperate for something new, go the wrong way and others still follow. In recent years Stubbies or 3 batten sails come to mind.

And basically all these things count for sails as well.

Witchcraft moved from Terschelling, a dutch North Sea island (not that bad at all for windsurfing) to Fuerteventura in 1993, simply to windsurf a lot more frequently in better conditions.
Terschelling 1987:

Fuerte 1996:

Here on Fuerte we have a wide variety of all kinds of conditions, right in our back yard and a good variety of local riders, including the people making the equipment, getting a lot of added and
direct feedback. We regularly have clean laboratory like conditions but also choppy waves, long soft waves, hollow waves, on shore waves, off shore waves,  close out waves, Jaws like conditions, flat water or B&J. We have light winds and high winds plus added conditions at Sotavento, Lanzarote or Pozo. We have shallow waters, rocks, sand and UV light attacking equipment during sailing and rigging. Material wears down 4 times faster here so you know lots faster what is good or not. All this forced us to quickly improve loads right from the beginning and has continued to do so over all these years.
I am sure that even a small thing like the slot box would not have made it into production if it had been tested by the locals here. Various have tried to set up business here but only lasted a few years and in the end couldn´t even sell their stuff for 1/3^rd of the price. And for sure not materials like Carbon-Kevlar or even more stupid constructions like putting thin Dyneema over carbon. Even if your engineering skills lack and can´t figure out before hand why this is a bad idea, after one time being washed on the rocks and having to repair it yourself, would have made it clear it´s a worse solution than plain glass fibre at a fraction of the cost and it would never have ended up with an amount of customers who were told they bought something strong “as it has Dyneema”.

You´ll struggle to find any location on earth offering such a variety of conditions within a short drive and amount of sailable days over a year’s time. Locations where up wind ability and early planing is very important to get on a wave first but then, once on the wave, turnability, control and keeping speed is also very important. This has also led to the development of our pre-twisted fins and the flex tail.
 
Our working hours and the short drive allow us to sail every single day there are conditions, which, with foiling and surfing included, is at least 300 days per year if you want to.

Then we also get feedback from an international team of riders of different levels. And sailing in different locations along the coasts of most European countries and travelling abroad. Using just one or 2 boards and one set of sails, just like most end users.

Plus, as we have direct contact with most of our customers, they also provide us with valuable feedback, they can contact us directly with any problem, question, suggestion or simply say how happy they are. In the end, a happy customer is the best promotion.

And maybe you may still think, well I do not sail that frequently in such demanding conditions. Well first of all, if you do not have such frequent conditions, any windy day is even more valuable and any day lost can´t be made up for, ever. Secondly having better developed equipment with a wider range simply gives more fun on the water. Thirdly having more durable equipment pays of in the long run, it has a higher resale value if you want to renovate, it allows you to plan equipment renovations better and you will not be forced to buy something quickly that is less value for your money and may not be exactly that what you were looking for. And last but certainly not least, it is better for the environment.

Mast box constructions

Today we are looking at different mast box constructions. Our standard mast box construction, the standard mast box construction of regular production boards and the construction of pre moulded carbon boxes into a PVC block.

Forces
The biggest force on a mast box is vertically from flat landings. Another force can be a pull force on the nut when tightening the mast foot and especially getting washed by waves. As a mast foot is made to bend, there are hardly any leverage forces like on a fin box.

For the vertical down force, it is important that the force is spread out over a big area of the EPS. This is achieved by making the area resistant to bending. And the best way to do this is by having a thicker PVC. The pretty much standard PVC reinforcement block around the mast box already spreads the force out over a bigger area. The wider and longer the block, the better the spread.
Though we have seen some custom brands where the boxes were just put into the EPS and nothing else, sometimes with glass, sometimes even just with resin. Steer clear of such boards.

Both Witchcraft and regular production boards place the PVC block before the sandwich. Like this the inner laminate under the sandwich continues till the box itself, with an overlap of laminate with the PVC block. Boards that use a pre moulded carbon mast box need a much bigger hole cut into the deck sandwich to mount the block after sandwiching. Here the inner laminate is cut through and just makes a blunt connection without an overlap, creating a weak point at this spot. For a sandwich construction both inner and outer laminate are equally important. This weak point is more prone to break when the PVC block is not extended long enough at either end of the mast box and the mast foot is mounted more towards either end and the mast foot does not sit fully on the PVC block any more. Normally an adjustment of a few cm already is enough so we like to keep the box short.

Then, apart from the PVC block, we also put a bigger area of double sandwich around the area of the mast box.

As the resistance against bending goes up exponentially with the sandwich thickness, a double thick sandwich is about 6.7 times as resistant. We also taper the double sandwich away so the inner laminate can be continued and does not need a second layer.

Here the view from our CAD/CAM program showing the reinforcment block and the double sandwich area and in the second all the blocks and inserts, which are all milled by CNC to the 0.1mm exact and saves a lot of measuring time. The asymmetric positioning of the mast box is on purpose as the back part of a mast box can´t be used. There are parts we do not show and also the mast box construction of the HDD and XHDD is very different than this but we don´t want to reveal too much to our competition.

Here is the cross section of a pre moulded carbon mast box:

Here is how the inside of a regular mast box construction looks like:

Injection moulded plastic boxes with a high content of glass fibre are slightly heavier than carbon boxes. We use a pretty short “(ST)RONG” box from Chinook which weighs 65 to 80gr.

The Chinook boxes we use have a high content of glass fibre inside the plastic which is injection moulded under high pressure. These boxes are very though and consistent in quality. There is also more material holding the nut. Chinook boxes have another useful little detail and that is a small notch at the back so that if the mast foot becomes unscrewed a little, it still can´t slide out which can cause some dangerous situations and loss of your board or entire equipment.

This time some differences that are not so small and all the more significant.
I often get asked why the rails on Witchcraft boards are quite a bit sharper than other brands. Then I ask why do they make them so round? Nobody really seems know. Maybe it is “because everybody does them like this” or shapers presume: “wave boards should have round rails”. I really don´t know, maybe no other brand has tried this. Like with our pre-twisted fin system. At least I have not seen any other brand try sharper rails and found round rails are better. Maybe it stems from the often very choppy wave @ Hookipa where you often see the riders bounce down the wave and the wave has a lot of forward speed so you do not have to carve as hard back to the wave. There are only a few other spots in the world which are similarly choppy, in Western Australia there are quite a few and a few other unusual spots like K-Bay in the UK. Most of the time this is due to having off shore reefs where the wind chop can run in a 90° angle to the ground swell. It may also be a back wash off the beach or an unusual rip against the wind. Even an high wind on shore spot like Pozo can be surprisingly clean compared to such side shore locations. Maybe it even stems from surf boards which are hand laminated without vacuum and  some “clever” board shaper found it is easier to laminate round rails and said “this is better for surfing”.

But is that so? First of all sharp rails plane lots earlier. You simply have a lot more planing area plus a clean release. See below comparison table for the average amounts of “tucked under edge” on boards we have measured. In the centre we have measured up to 22mm of tucked on some boards. So there can even be 12mm difference in tucked, meaning there is 24mm (!!!) less width in the planing area.

Here a few measurements on various boards: from left to right: bow, centre, front strap, fins

Tucked under edge comparison in mm:

Still when you have the board on the rail in the bottom turn, you feel the whole width which makes it harder to control and keep it on the rail. So with round rails you have a board that either planes less early or that is harder to keep on the rail.

In the front, the rails should be round, here the water has to be guided under the board and a sharp rail would cause more drag. Airplane wings are round in the front too. But from the centre back, we push down a lot harder on the board and even more so with the G-forces  in a turn. From here the water wants to escape this pressure so flows outward. Once the water is only flowing outward, there is no need for round rails.

Nowadays high tech CFD simulations are getting very realistic and provide very interesting information for a shaper. It allows a shaper to “see” under the board and get information on the water flow and water pressure under the board. Information that was previously pretty much impossible to obtain. Our CFD simulations also show that in the back half, the water flows outward and the second image shows the pressure distribution which causes a board to turn.

And the clear waters of Fuerteventura also allow for under water filming: 

Especially in slow motion you can see a lot more that other wise happens too fast.

Secondly sharp rail also go up wind better so you can get more waves or jumps. A round rail in the back sucks a board down in the water before it releases and stalls sooner when the speed drops.

The Rudder Effect
Then another important effect is for turning, sharp rails in the back half of the board also turn better. When you enter a turn, the taper of the outline works like a rudder. If you draw an imaginary line through the widest point of the planing area (so not of the outline) and the edge of the planing area under the back foot, this line makes an angle with the centre line. So when pushing just a little bit on this rail, the rail “guides” the board in this direction. The bigger the angle of this imaginary line with the boards centre line, the bigger the effect. By weight placement you can also vary the amount of rudder effect, lean more forward and the entry point is more forward leading to a smaller angle with a smaller rudder effect thus less reactive. And by sailing more on the back foot the angle becomes bigger and the board more reactive.
The outline taper is a great tool to tune the character of board for different conditions or types of sailors. I give a board like the Reaper more outline taper to make it more reactive in small waves in spite of its flat rocker line. And the Wave V5 has less because it has more rocker and needs more control in bigger waves. These shape differences are also supported by the foot strap positioning of different shapes.
Here a comparison of the Wave V5, Chakra V3, Reaper against a Stubby:

Also the sharper the rail, the bigger the rudder effect. If you do not have grip with the front wheels of a car, you can´t turn. So the bigger the “rudder effect”, the more reactive the board will be. The only down side can be that a board can become too reactive, for example bottom turning when it is choppy. For this reason, easier going shapes board like the Chakra or to be sailed in smaller waves with more chop like the Reaper have a bit rounder rails than the Wave (V3, 4 or 5), which is made for cleaner waves. What you usually see when waves get bigger, the area in front cleans up when the wave takes shape and gets steeper. Even on shore conditions are usually not so choppy when the wind gets stronger and the  waves get bigger. When sailing in a straight line, rails do not make a difference in handling chop. Also the lower control in chop can be dealt with by using less rocker for example and have an even bigger wind range.

So both these features help to enter the turn, Then once we have entered the turn, we engage more rail and the rocker takes over the main role for turning. By leaning back or forward you can use more the taper or the rocker to adjust the turn.
Here is Will craking a tight bottom turn:

Grip
Grip is king, an F1 car on wet grass would be all over the place. After all, we are sailing on water, not tarmac, ice or sand so high grip is still relative.
When having the board on the rail, a  sharp rail also has many benefits: Less rail slip, more grip and drive, more precision. You can sit higher on a steep face, get more speed out of a wave and keep more speed through the turn.

Like the Boards.co.uk test team already wrote in 2007 when testing the Witchcraft Wave : “the rail bites beautifully and accelerates you hard into the wave”.

And www.windsurf.co.uk in 2011: “On the wave it has a versatile carving style and it is able to hold its speed incredibly well through the turns”.
And a high grip is also very usefull when cranking top turns:

And when you keep the board flat or look for some foam, it is still easy to lose the tail, as Will is demonstrating here with a lip slide and a taka:

Wind range.
Apart from for turning, having more outline taper also gives a bigger wind range, you can adapt the needed planing area better to the amount of wind power there is. Wider in the front to get planing and the faster you go the more you can reduce the wetted area to have more control and top end speed once planing. Boards with parallel rails miss out on the increased wind range and reactivity of a tapered outline.

Our back yard is the North Shore of Fuerteventura where, within a 10 minute drive from our R&D centre, we can find many world class wave sailing conditions. We have spent over 25 years of testing in some of the toughest conditions you can find, repairing damaged boards and developed composites engineering techniques to perfect our constructions. When you have demanding conditions at your door step you get to see frequently what works and what doesn´t and learn a multiple times faster than in locations without such conditions. Throughout our boards you can find intelligent but still very logical and practical solutions, using the specific qualities of the various materials there where they are needed most.

Witchcraft is famous for the “bulletproof” HDD (Heavy Duty Dyneema®) constructions. Not in the least because of this video: The Witchcraft Hammertest. Also visitors to our rental centre and custom board factory on Fuerteventura can do these tests themselves and many already have.

Dyneema® is also known as UHMWPE or Spectra. We have been working with the fibre since 1994 and know all the do´s and don´ts of this high performance fibre. Till today there is no stronger fibre.

Here some images of boards that were battered on rocks without any hole:

Dyneema has some very good properties such as tensile and impact strength but also not so good properties such as compressive strength, sandability or bonding to resin. Over the years we have found ways to solve these problems  and still come out with a better board. We have tried various high tech treatment methods till we found the right one and have our Dyneema specially made to our specifications.  Another trick is to use each material there where their properties are most needed.
See comparison table of properties*.
Since the properties of Innegra are far worse, we do not use it. But also Aramid (Kevlar, Twaron) does not bring any advantage over Dyneema so we don´t use that either.

Stiffness
Now what is very important when combining different fibres is to compare stiffness and elongation at break of each fibre. The stiffer the material the more force it will take. When you want to combine materials, the stiffness should be as similar as possible so the co-operate OR you take care the stiffer material alone is strong enough. For this reason a material like carbon-kevlar is pointless. You think you have the best of both worlds but in the end you only have 50% of each. The carbon will take the most force but there is only 50% of it. When that breaks there is only 50% kevlar left and even if that wouldn´t break, the board still needs a repair which is very difficult with the carbon and kevlar woven into each other. When you have a block of concrete of 100kg and a  steel cable that can lift 90kg, what will happen if you add an elastic that can also lift 90kg? First the steel will break and then the elastic. Had you used either steel or elastic that can pull 100kg by itself, things would have been fine. For this reason simple glass is just as good as carbon-kevlar but lots cheaper and easier to use and repair. Carbon-Kevlar (or carbon-Dyneema or carbon-Innegra) only serves marketing, you think you buy something high tech and durable when in fact you do not.

Here is also a nice explanatory video on the subject: Why you SHOULDN’T wrap Fiberglass in Carbon Fiber!

So what we do is to use a full laminate of Dyneema, both on the deck and the bottom, overlapping on the rails. To be able to finish the board, the Dyneema needs to be covered with carbon or glass. As glass has a much more similar stiffness to Dyneema and is twice as impact resistant as carbon we use glass. The main part of the problem of the lower compressive strength of Dyneema is solved in a secret way. And then on top of that we reinforce the areas that are under high compression loads with carbon. The bottom is especially under high compressive load when landing flat. See image below of the forces on the bottom of a slalom board in chop (image 1). The forces when landing flat with a wave board are similar but higher. The bottom sandwich is compressed from the front and back and the water pushes up. As long as the bottom sandwich stays stiff and does not flex, the forces are spread more equally (image 2). The more the sandwich can flex inward, the less favourable the situation gets and the load on the outer layer increases quickly. (image 3)

Hence the main cause for breaking a board is when the bottom can flex inward and finally the outside laminate creases. Carbon UD is the best material to resist compression and creasing.

With carbon we are always taking care that WHERE we use carbon, we use ENOUGH to take the whole load and that where it stops we make the transition very gradual, to avoid sudden differences in stiffness which create weak spots when the whole board is flexing like upon flat landings. Like this the high impact areas such as the nose and rails are just Dyneema or double Dyneema covered with glass. Carbon is the worst material for impact. Also keeping carbon away from these areas means we still allow for some flex in the board, absorbing peak loads. As the saying goes: What bends doesn´t break. If you look well, you can see the carbon UD on the deck and bottom on this board below. The deck does not need much as a compression load is rare and lower.

Repairability
In the whole of the board construction we always think of repairability as well. No matter how impact resistant a board can be, rocks are harder. Since a board made out of rock would be slightly on the heavy side, we have to live with the fact that damages still can occur but we try to limit the damage and make it easy to repair by keeping the damage superficial as much as possible.
Where carbon is needed for its higher compressive strength, it is placed on the outside so that if it damages, it is easily repairable. The Dyneema underneath will still prevent further damage inside. Delamination of Dyneema can occur as the available resins today are simply not as strong as Dyneema. However delamination is easily repaired by injecting a bit of resin with a bit of heat to make the resin more liquid.
We use a sandwich material that is especially for dynamic loads and has memory, between 80°C and 100°C it comes back into its old shape, allowing for dents to be heated out.
The nose is also made with Dyneema under the sandwich and 6 layers of high grade glass fibre to prevent impact damage of the mast. Some people seem to think that if you can hit a board with a hammer, it should also resist a catapult on the nose. However a rig weighs +7kg with a lot of leverage when hitting the nose and a good RDM mast has 4mm thick pre-preg carbon with a round shape. The impact between mast and nose can become so big that something has to give. Either the nose or the mast. Take your pick. If the mast breaks you will have to swim back and the damage is far more costly as masts can´t be repaired and usually leads to damage of the sail as well.

The result: The Witchcraft HDD construction is the best construction for wave boards money can buy. It can´t technically be improved, even if you would want to pay double. And this also means it is the best for the environment and your wallet.

Dyneema is not always Dyneema.
As Dyneema has gotten a very good reputation for impact resistance we also see other brands using it now but often in such a way it completely misses the point. We had one board in for repair with various holes from small impacts which had visibly a full but thin carbon BIAX laminate on the deck and bottom. But the owner said it was Dyneema and he was wondering why it got holes so easily. It turned out it did indeed have a layer of Dyneema covering the carbon but it was very thin, about 1/3rd of what we use. Dyneema is not rubber, any impact will get passed on to the carbon 1:1. With the hard and brittle carbon underneath, this thin Dyneema still could not absorb the little impacts and got punctured. Also in places where it wasn´t punctured but had received compression dents of the mast, the thin carbon underneath had broken, which could not be repaired without removing the covering Dyneema over a bigger area, which then can´t be repaired again because of its poor sandability.
In such a lay up, the use of Dyneema is actually making things worse, it would have been better without Dyneema. Just with carbon it would have been as strong but lighter, cheaper, easier to make and easier to repair. Or even having it made with simple glass fibre would have been more impact resistant, with the same weight, as strong, lots cheaper, easier to make and easier to repair.

So if you see a board that says Dyneema but looks like it has full carbon, don´t buy it. Even if we have spent 20+ years to give Dyneema the reputation it has today, if used by inexperienced people in the wrong way, the outcome may actually be worse. Dyneema is not always Dyneema.

Our back yard is the North Shore of Fuerteventura where, within a 10 minute drive from our R&D centre, we can find many world class wave sailing conditions. We have spent over 25 years of testing in some of the toughest conditions you can find, repairing damaged boards and developed composites engineering techniques to perfect our constructions. When you have demanding conditions at your door step you get to see frequently what works and what doesn´t and learn a multiple times faster than in locations without good conditions. Throughout our boards you can find intelligent but still very logical solutions, using the specific qualities of the various materials there where they are needed most.

One example are our fin boxes. Experience shows that the biggest forces on a fin box is when hitting bottom. And experience tells us that sooner or later prtty much anyone will hit the bottom with their fins.  When we started using multifins we thought we can sail in shallower waters and still hit the bottom.
The best way to place a fin box is to first place the reinforcement block together with the sandwich so there is a big connection area between block and sandwich with laminate in between. This even saves time. Also the harder sandwich sheet then sits directly against the box without the slightly softer reinforcement block in between.  After the reinforcement blocks and bottom sandwich, the cavities for the boxes are milled by CNC, this saves a lot of measuring time and is accurate to the 0.1mm and 0.1° of toe-in angle.

The Chinook Strongbox US box we use is made of very tough plastic reinforced with a high percentage of glass fibre. Glass fibre is twice as strong against impact as carbon and the high pressure injection moulding technique used ensures the fibres are in every corner and the automated production process is failure free. The thicker walls of the Chinook Strong box also provides a bigger area to take the impact from hitting the bottom. We mount the boxes with various layers of high grade glass fibre which is then smoothly guided over into the bottom sandwich for the best load distribution.

As a comparison here is also a carbon slot box, pre moulded into the reinforcement block before mounting into the board. The box needs to be placed after the sandwich, for which the hole cut into the sandwich needs to be a lot bigger. The carbon box is lighter but carbon is also very brittle and does not handle impact well. Carbon is especiall brittle where it is making a sharp corner. Reinforcing with Dyneema or glass is pointless, as carbon is a lot stiffer, it will take all the force and the glass or Dyneema will not do anything until the carbon is already broken. Also the weight saving is done by using a thinner wall, causing the area to take the vertical load from hitting the bottom to be much smaller. The screws of slot boxes are also not ideal to take the load from hitting the bottom. The angle is far from ideal plus there is little material to stop the screw from breaking out.

Then you also get the more products from factories aimed at bigger quantities which often do not work as accurately. This can lead to production mistakes likes this where the fin box and reinforcement block are more or less floating inside the reinforcement block. This is likely to break easily when hitting the bottom but it may be hard to get guarantee after hitting the bottom, if you are still within the guarantee period at all.

Haka ST 90L – personal review

Haka ST 90L and Slayer 4.2m2 offshore Levante in Valdevaqueros – Tarifa

Last summer arrived my fresh Haka ST 90 liters. After one season I feel like wanting to share my personal opinion about it. I will not tell about the technical matters, but about what I feel on the water so give a personal feeling release.

Haka ST 90L and Karma 4.7m2 small waves in Canos de Meca.

My profile: I’m an experienced windsurfer and windsurf coach since 25 years on high skill level. I used to freestyle in combination with waves, so I windsurfed with freestyle boards 90-100 liters in waves for many years. The past 10-15 years I focused only on wave windsurfing on small and larger wave boards, with some remains of freestyle moves in between.

I weigh 76-77 kilograms and my height is 182 centimeters.

When I hesitate about what sails or board to use, I mostly choose for a smaller sail on a larger board, so the 90L had a lot of sessions in many conditions from 5.3m2 in very light wind, 4.7m2 light in larger waves 2,5 meters in Tenerife to even 3.7m2 gusty with small waves in Tarifa. I experienced a lot of different conditions on several spots.

Haka ST 90L and Slayer 3.7m2 in Bolonia

My general opinion and feeling: with the larger volume for a waveboard, 90 liters sounds a lot, but it works in so many conditions. The stability with 5 knots is difficult, but once you get 10-12 knots you can float and start to make some speed and height. Despite the pretty small fins, it starts planing extremely fast from 15-17 knots in combination with the powerful Karma 5.3m2 sail that gives an incredible push and a fast acceleration, so I can windsurf as fast as when the kiters start not losing their height. Giving pressure on the feet and pumping the Karma give an amazing energy shot! Sailing the Haka ST 90 liters in combination with 4.7m2 Karma and 4.2m2 Slayer with waves 1 – 2,5 meters always works incredibly good. In wind drops I just need to stand a little bit more straight above my gear to keep the planing. In stronger gusts it’s just the opposite, it never loses the calm and fast contact with the water. Side, of, on, strong and constant, gusty, any wind, … for jumping you just need to push a little bit, it easily accelerates so flying is a true pleasure on any wave size or direction. This is very important to me, because jumping is my number one thing. Same feeling for waveriding. Once you are used to the board and knows where and how many pressure to give, this board gives a boost in 1 meter waves to big and pushy waves in onshore wind. It turns smooth or fast down the line and is performant to take aerials and very aggressive short turns on any lip. Even when there are no waves, I like to sail around for performing my windsurfing lines towards the wind and downwind, and the Haka ST 90 liters give me an impressive upwind and downwind performance, especially with the small wave fins and in combination with the powerful Witchcraft sails. Working on my body positions give me the feeling of windsurfing in a slalom or race event, cruising and enjoying the sun or the scenery. And this exercise helps me out to perform better in the waves.

Haka ST 90L and Karma 5.3m2, choppy waves in Normandy

Any less points? I don’t feel the inspiration to take out with my older freestyle moves. Popping up and sliding are more difficult, but I don’t mind because I look for more waveriding and jumps. If you look for a more performant board with freestyle capacities, it’s better to take the Reaper or Ouija. When the wind is above 35 knots and pumping harder it still works pretty well, but I start to make mistakes and a smaller board is much better.

Haka ST 90L and 4.2m2 Slayer, powerful big waves in Wissant – France

Conclusion : Wauw! The 90 liters Haka ST is incredibly performant and ready to use in so many ways. It gives a lot of possibilities for windsurfers in flat, choppy, small and big waves.

I really love it and would like to let it try to everybody. Everybody that tried the board for so far, had the same feeling. It gives an impressive dimension towards comfort, fun and performance in windsurfing!

Fabrice Devos

Haka ST 90L and 4.2m2 Slayer Wissant – France

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