Fins on a Raceboard - why not right-angled?

[jaros]

Hi,
Why are the fins on the kitesurf raceboards not installed at 90 deg. angle, like they are on the windsurf formula boards? Both boards ride flat (I guess) so why the difference?
Greetings,
Jaros

[Peter_Frank]

Hi,
Why are the fins on the kitesurf raceboards not installed at 90 deg. angle, like they are on the windsurf formula boards? Both boards ride flat (I guess) so why the difference?
Greetings,
Jaros

Okay - I thought a lot of the race boarders would immediately answer your question - but apparantly not...

And I think this is because there is not really full agrement on what is best

Raceboards are NOT ridden flat !

Compared to a TT, yes, it might seem flat.
But for a raceboard rider it is NOT flat.

For pumping into planing, flat is the way, true. But when planing, a slight angle seems to give better control and the least drag - also according to my personal experience.

You can not compare to a Formula board - as they have the mastfoot pressure to give a completely different animal

So maybe we are better off with a bit longer "edge" in the water, when planing, thus a slight angle will give this ?
Dont know for sure - but it seems like that.
We have a slight upward pull the windsurfers dont have to the same extent, so we would like to reduce wetted area not only by planing at the fin and tail, but also by making the board "narrower" and still using the fins (?)

----

On the runs, some ride flat, others ride slightly edged for speed and control.

But upwind, they have a slight angle (edged).

So some think that having the leeward fin fully straight, and the leeward lifting a bit, will work best.
Others think that the "cant" should be low or zero, for max efficiency...

But both types are used by the very best in racing, so it seems that there is no general take on what is best

On the runs the cant angle means a lot for control - but which is best and why ?

I talk to some of the very best riders nationally and internationally - so thats why I can say that noone really know what is THE thing to use.

Almost like thruster versus quad fins on waveboards ? Well, there you can at least FEEL the difference - here it might be even smaller...

But like on waveboards, the board should be seen as a whole unit - shape and foot strap position and fins as ONE - so many different constellations would work equally well maybe.

Just some of my knowledge and thoughts....

Peter

[marshall10488]

ok this is from what i understand from someone trying to teach me how to use a race board correctly and why they designed it how they have (they design their own race boards)

To get a race board to go up wind you need to...
1. flaten the board off. any edge increases drag and slows you down, therefore lowring your angle into the wind.
to flatten the board off you need to push your toes in (opposite to TT riding)
2. lean forward. get your weight over your front leg more.
3. pull bar back. pull the bar towards the back of the board
4. slide you back leg out. try and push you back leg away across the water to point the board upwind more.

this is how i have understood what he has told me about ridding race boards. more then likely he will jump in soon and call me a retard and explain it better.

but on some boards they have 0 deg toe on fins

[Peter_Frank]

ok this is from what i understand from someone trying to teach me how to use a race board correctly and why they designed it how they have (they design their own race boards)

To get a race board to go up wind you need to...
1. flaten the board off. any edge increases drag and slows you down, therefore lowring your angle into the wind.
to flatten the board off you need to push your toes in (opposite to TT riding)
2. lean forward. get your weight over your front leg more.
3. pull bar back. pull the bar towards the back of the board
4. slide you back leg out. try and push you back leg away across the water to point the board upwind more.

this is how i have understood what he has told me about ridding race boards. more then likely he will jump in soon and call me a retard and explain it better.

but on some boards they have 0 deg toe on fins

Toe in is not the same as cant... But I know you know what we are talking about (cant angle - fins angled out to the sides from board surface down to the tip).

But the raceboards are NOT ridden flat, believe me, I know that for sure

As I wrote - flat compared to TT's of course, as they are almost only ridden edged - but still not flat on the upwind legs.
It might seem so flat, that you can not notice any angle (we are talking a few degrees only of course) - but there is an angle.

Interesting to hear what others think and have heard, yes

Peter

[jaros]

Thank you for your answers. I guess we will see receboards evolve a lot in the next few years. the 2010 are very different from 2009 from what I cn see from photos online. In real life I rearly see a raceboard around here.

To get a race board to go up wind you need to...
1. flaten the board off. any edge increases drag and slows you down, therefore lowring your angle into the wind.
to flatten the board off you need to push your toes in (opposite to TT riding)
2. lean forward. get your weight over your front leg more.
3. pull bar back. pull the bar towards the back of the board
4. slide you back leg out. try and push you back leg away across the water to point the board upwind more.

Those are the same things I used to do on my windsurf to go better upwind!

[Peter_Frank]

Thank you for your answers. I guess we will see receboards evolve a lot in the next few years. the 2010 are very different from 2009 from what I cn see from photos online. In real life I rearly see a raceboard around here.

To get a race board to go up wind you need to...
1. flaten the board off. any edge increases drag and slows you down, therefore lowring your angle into the wind.
to flatten the board off you need to push your toes in (opposite to TT riding)
2. lean forward. get your weight over your front leg more.
3. pull bar back. pull the bar towards the back of the board
4. slide you back leg out. try and push you back leg away across the water to point the board upwind more.

Those are the same things I used to do on my windsurf to go better upwind!

Yup - or just to get planing - so it is very easy and natural for us "ex-windsurfers" riding a kitesurf raceboard

[gmb13]

Yep,

At the moment we are learning that a lot of the Principles from Windsurfing works well for Raceboards.

The most recent Board I designed was based mainly of Formula Windsurf Principles. Scoop, Rocker, Rail and Deckshape are all inspired by Windsurf Raceboards.

I personally try to keep the fins as close to a 0° angle if possible, but still need to angle the Front fins so that they don't interfere with the back fins.


I found that my Best VMG (velocity made good) is when I am pushing the Heelside rail and the board is board is almost being pushed onto the opposite rail. The Board is totally flat in this state.



--
Gunnar

[zerogee_ca]

How about placing the straps out on the opposite rail (toeside rail) and orientating them so that your heels are across the centerline of the board. Perhaps this could make it easier to push your toes to flatten the board. Is that a wacky idea or what?? Don't ask me how you would ride the thing though. Maybe it has been tried already. Excuse me while I have some more of what I am smoking right now...

[Peter_Frank]

How about placing the straps out on the opposite rail (toeside rail) and orientating them so that your heels are across the centerline of the board. Perhaps this could make it easier to push your toes to flatten the board. Is that a wacky idea or what?? Don't ask me how you would ride the thing though. Maybe it has been tried already. Excuse me while I have some more of what I am smoking right now...

Okay, we got some differing statements here now...

Gunnar - are you competing in racing or "just" sailing raceboards ?

No offense - I dont compete either, but talking with my three friends who are ranked quite well in the PKRA Racing.

Their take on this is, that the boards is edged just a tiny bit to windward most of the time upwind.

(I and we might be wrong though, I dont state anything for certain now...)

But of course, it also depends on wind strength - as higher wind tend to lead to somewhat different riding style for many.

I dont know - can also be extremely board/fin specific - thus we get these contradicting statements here
Quite interesting in fact
-----------------

Regarding the footstraps - well, actually no, the problem is the opposite now, they place the straps further to windward, in order to be able to hold the edge down, as the fins they ride are MUCH bigger than "we" (freeride) would ever like to use, and wider boards too.

Big fins means the board will trip to leeward easy and need pressure to be held down.

Again, very design specific also.

Some even put two back straps on the board, in order to be able to put pressure on the leeward edge. Just like on Formula boards.

On the first "small" (narrow) raceboards, one front strap were used, but havent seen many with this lately (or anyone in fact).

Still so much development going on, and you Gunnar, is maybe on one specific track where it is leeward edge that works, where others are going windward edge.

Will be exciting to see how it evolves - but anyway great that we have got all these lovely boards to ride now in light wind and for kite trips

Peter Frank

[gmb13]

I will be competing at the Worlds in Corpus and the rest of the PKRA Races this year.