DW board potential track issue

Downwind Foil
22

Thinking more about this as I’m building a board and about to put money into a track placement… so here is my take on downwind track positioning.

Even on newly released boards, competent riders just end up with the foil right at the front nearly immediately. I rode a demo Appletree appleskipper downwind and a demo Axis hybrid downwind board and both I had the foil at the front of the box by the end of the first session

I have two thoughts and a theory :

  1. To paddle you need to stand near the middle of the board for optimum speed/efficiency, this needs to also accomodate where you stand when catching a wave, not just flat (adjusted ~forward/back depending on volume distribution),
    This is what restricts the track position

  2. When on foil you want your feet to straddle the lift point of the front wing, approximately (proxy to this is the backfoot being on or slightly in front of the mast). you will move your feet to find the optimal place,
    Unrestricted as you don’t have straps, can stand anywhere, ideally near the middle for balance

  3. Key then is having the foil in a position that means transitioning between 1 and 2, you don’t end up adjusting your stance. A poorly positioned mast is indicated by either
    a) too far back, needs steps back on take-off to get above foil
    b) too far forward and getting launched before getting up enough speed

Based on above, you’d ideally then want the range of your boxes to centre around positioning the centre of foil (technically 1/3 from front) under your feet, with adjustments based on conditions.

Interested in feedback, do you agree with this theory? With this in mind I want to put the boxes similar to FFB below, or even further forward?

***Caveat would be that you’re designing around a specific brand and fuse length, and could end up not working on a different brand, but that is more a problem for production boards

Pic for interest

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image531×914 85 KB

2 Likes
23

To me, the tracks positionning depend on the shape of the board, especially the tail (wide tail/more volume vs narrow pin tail/less volume) and also the wide point of the board. With narrow tail and wide point forward I think tracks work better far forward, it is more balanced.
I like tracks far forward, more glide, less swing weight. Back foot over the mast at hight speed going down but moving back foot forward the mast while gliding casual.

2 Likes
24

Hey–this solution looks pretty effective, strong and not too time-consuming. I’ve got an NSP sup foil pro 6’2" and feel like my Takuma 1440 is too far back, limited by the track. Even being able to mount it 2" further fwd would be a vast improvement, and probably make paddle-ups easier. How wide did you make your plate (how far did width go past each track, laterally? Thanks!

25

It looks like a bit over an inch out from the holes. You don’t happen to use a no limitz mast? The holes are spaced for that and could sell you mine?

26

Currently, I don’t have a NL mast. Takuma and Cabrinha…

Thanks!

27
  1. The centre of buoyancy of a board determines where the rider stands on the board.
  2. The centre of gravity of the rider then determines where the centre of lift needs to be.
  3. The centre of lift is where the front wing needs to sit.
  4. The mast then goes however far back on the fuselage it is setup, with the foil in the correct place.

That is the basic formula ( there are finer details but this will get you close )
The unknown in the equation for each designer to work out, for any given shape, is where the centre of buoyancy, relative to the riders centre of gravity, works best. That then comes down to prototyping and testing!

js.