q for ian diffrence downforce code red and warp 2007

[erik]

Hi ian,

I sailed code red 1 and gonna sail warp 2007.( with isonics 2006)
I heared that the warp has more downforce in compare to the coder red.

Does this mean that i can place footstraps all the way back with the warps, because the warps push the nose more down?

with the code red i had to place footstraps in middle hole and baseplate almost in front, otherwise the sail wanted to push me to the nose and i didn't feel in balance.

greetings

erik

[Ian Fox]

Hi Erik,

Code Red 1 is a moderate downforce sail, I really don't know the Warp 2007 so well. Usually the downforce also varies (somewhat) with sail tuning.

For the trim, with Warp the first adjustment would be to move the mast plate back. Moving the straps back can (may, relates to chop etc) help also, however going too much back on the straps in chop reduces the rider;s ability to calm the board and keep the power on.

Cheers ~ Ian

[Roger]

Hi Ian,
Can you define "downforce" here?
How is it measured?
Who measures it, or is it a "feel" sort of thing?
I know that horizontal wings (on aircraft and racing cars/boats) can be used to create "down force (race cars and boats) and "upforce" (aircraft), but I'm puzzled as to how a vertical foil can produce "downforce"?
If we rake our rigs too far upwind, then I can see an "upforce" component (the same with laying the fin over a bit by lowering the lee rail) but "downforce" escapes me.
Roger

[Ian Fox]

Hi Roger,

"Downforce" is not my word, but commonly used to describe what I refer to as "dynamic weight", that's to say, a sail(rig) in use, under load imparts a load (downforce...) onto the board greater than it's static (actual component) weight.

As the mastfoot is the pivotal leverage point of the rig, you can see that the forward vector of the sail's "lift" loads on the mast track, itself also part of a lever (or leveraged point) in the boards longitudinal trim. Jim would define it better.

Different sails - and even different tunings of the same sail - influence that loading, which in turn (can be used to) influence or optimise the trim of the board. Varying the mast foot or strap location, you're adjusting the leverage "length" of rig (or rider/straps), in turn trimming (balancing?) the balance beam (board).

It's all a subtlety, but so is fin flex- and what a deal that turns out to be.

Cheers ~ Ian

[Ian Fox]

PS : In theory you would measure it with a load cell under the mast base and go out blasting, in practice that would get a bit wet and probably spoil the results so a more practical but non finite "measure" is in fact, the trim of the board.