"TWIN-TIPS ARE SHORT ENOUGH AREN’T THEY - WHY DO WE NEED ONE THAT SPLITS IN TWO?" WAS THE SECOND QUESTION WE PUT TO MARK SHINN FOR THIS INTERVIEW. THE TWO-TIME WORLD CHAMPION AND CHIEF MECHANIC AT SHINN BELIEVES THEY’VE MADE A SPLIT BOARD IN THE SLICER THAT RIDES AND FLEXES AS WELL AS A ONE-PIECE PERFORMANCE FREERIDE BOARD. "WERE YOU ATTRACTED BY THE IDEA OF A TWO-PIECE BOARD FROM THE FIRST MOMENT YOU SAW ONE?" WAS OUR FIRST QUESTION: “DEFINITELY NOT!” HE REPLIED...
INTERVIEW: Jim Gaunt
Mark continued... At first I thought this was the classic case of technology for technology’s sake. A solution to a problem that doesn’t exist. The first split boards I tested didn’t perform very well and were fragile. I couldn’t understand why anyone would be happy to compromise their riding on vacation to save a few euros in baggage charges. Over time I realised their existence is justified, but the solutions I saw were flawed. Twin-tips are short enough aren’t they? Why do we need one that splits in two? There is a magic number: 158 centimetres. If you travel low cost or charter flights this number doesn’t really matter, but if you fly scheduled airlines this is the maximum size of a standard bag: length + width + depth. Exceeding this puts your bag into the realm of excess luggage and the charges can be huge. This was the classic example of why split boards came to life, but in reality the benefits stretch further.
If you own a small car, a two-piece board is more convenient, as it is if you travel by train, bus or taxi... What we wanted was a great kiteboard that splits; not a board that splits that you can kiteboard on.
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You’ve mentioned to me previously that this was a very difficult design to create successfully. Can you run us through the main issues? There are a couple of tricky things to solve in a good split board. The most obvious is to make a board that has great flex, good weight and doesn’t break. We wanted to make a board that feels like a normal ride and that meant dealing with the classic split issues of reduced flex in the centre of the board. The connection has to flex, yet be strong. We came up with the concept of making the split as a three-piece construction, utilising the centre part (connector) made of flexible but unbreakable PU. Having a connector that flexes would completely resolve the flex issue. Having a great idea is a long way from having a functioning end product! My team and I have learnt a lot about PU and moulding in the 18 months since we started the project. The S connection is obviously the key. Is there a secret to the depth of the S curves? When constructing any board we always avoid any mould or lamination straight lines that pass from one rail to the other. This is the weakest part of any board and adding construction lines in this direction is dangerous. Using the S connection means that a large part of the connector is orientated in the tip to tail direction, which is the strongest orientation it can be. The problem with this S connector is that in a traditional board the connector has the same lamination as the rest of the board and when you assemble the split the overlap means you end up with double the lamination over the connection. Let’s assume that the S shape is around 15 centimetres wide in a tip to tail orientation; that is a significantly stiff area added in the centre of the board. The concept of using PU is that we can have the best possible structural shape of the connector but that the laminate is not increased over a normal deck. As the connector itself flexes, we end up with complete structural integrity and yet also have a flex profile in line with a standard TT. Win - win!
How easy was the PU material to develop? Integrating the two different technologies (board pressing and PU moulding) presented some very special challenges and I lost count of the number of prototypes we made. The hardest part was ensuring a perfect fit of the board halves and the connector. PU is the name of a group of plastics and there are myriad versions, ranging from skateboard wheels, surf leashes, TT fins and even car parts. Working to find the right chemical properties was challenging before starting the manufacturing process. Injection moulded parts shrink during moulding and kiteboards also have a manufacturing tolerance. Combining the shrinkage and manufacturing tolerances to ensure the connection is as closely a fitting as possible was not easy.
In the end the PU connector has a very similar flex to the board itself and on the test bed we simply can’t see a difference between the Slicer and a regular TT.
How do you test a board like this? On the water testing is the same as any other board; you go kiteboarding – A LOT to see how it holds up. Before that we did a lot more static testing than we would normally do, with a 500 kilo test rig. We also set up durability testing, assembling and dis-assembling the board to ensure the board will function the way it is designed to for a long period of time.
Were you close to giving up at all? No, but there was a period I would have liked to! The investment in moulds and tooling for the project was significant and a lot of it had to be paid up front – without the mould and tools you can’t even make the first sample – so once we’d started we were committed.
I do remember making a six hour drive in October last year in temperatures around three degrees to test what should have been a final prototype. The board lasted ten minutes before failing, so I had the six hour drive home again to consider the problem!
I think 12 hours driving for ten minutes kiting might be some kind of a record!
Do you think more of us will be riding spilt boards in the future? Indeed I do. In the past I always found split boards too much of a compromise, but when you honestly can’t tell the difference on the water, why wouldn’t you want the convenience of a split board?