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Old 1st September 2008, 05:07 AM   #1
mim
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Join Date: Jun 2008
Location: Switzerland
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Default Spin-out on S-Type 137...

Hi,

I had my first spin-out experience yesterday. And I have a few question on a gear setting, fin size and type.

Board:
S-Type 137 (2007) with standard fin 480mm (freeride flow), foot straps are inboard, mast foot half way back.

Sail:
Severne NCX 7.0, less downhaul (3cm less than specified), less outhaul (1cm less than spcified)...I really am big, I do not have the proper technique to get plannig without a lot of power in the sail and I really enjoy to be overpowered (btw. 7.0 is currently the biggest one...the right reason for underhauling! , I will buy a 8.5 but things go not fast all the time).

Wind:
average 15 knots, gusts 22 knots, small chop (up to 40cm).

Sailing style:
Get planning downwind, feet in foot straps (the board turns extremely up wind) --> sail in wind, pump a little bit get it again planning full speed downwind --> increase the back foot pressure to keep speed and go upwind (I lay my body towards the nose and sheet in the sail completely).

Result is a massive spin-out, me heading downwind with nose oriented upwind. I only can manage the desired direction when it is sligtly downwind, otherwise I get spin-out.

I did not see this before because this was the first time I used both footstraps and I could thus sheet in completely.

Do you think this could be solved by a longer fin, or maybe another shape?
I tried to change the trim slightly (like harness lines and body position and I tried to reduce the back foot pressure as well, this works a little bit but I do not get upwind, which I like a lot, and that is not good...)

I am opened to everything you advice me .
Thanks for any reply.

Ciao Michal.
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Old 1st September 2008, 06:07 PM   #2
Ian Fox
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Hi Michal,

Please check out the comments I posted down the bottom of the discussion at

http://www.star-board.com/forum/showthread.php?t=3857

and then feel free to ask or discuss any further questions too..

Yes, there are some differences but the draft control issues are relevant to your case also
(so rather than retype all that..)- the issues of downhaul/outhaul relation to draft control(especially under heavy wind or rider loadings)

Some additional factors in your case can be the relatively large size/volume/width of the 137 (c/w say , smaller slalom boards as discussed with iS101) plus the softer rail on the SType all tend to increase the reliance/work on the fin for directional stability. You may also find some further benefit to trying to run more off the wind INITIALLY to get up speed before loading the fin, especially when piching to windward.

The FreeRide Flow is generally an OK fin but also maybe more suited to cruisy, playful riding c/w hi load sailing, and making use of a more upright fin can give better lift vs size efficency, however with a 7.0 NCX you should not really need a whole lot more fin that 480 (and could normally get away with less in ideal 7.0 sail range)

Cheers ~ Ian
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Old 1st September 2008, 09:40 PM   #3
mim
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Join Date: Jun 2008
Location: Switzerland
Posts: 196
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Hi Ian,

thanks for the reply.

Well I do not have a problem sailing downwind (al least no spin-out).
But as I am speeded up and apply more pressure on the back foot, tilting my body forward and sheeting the sail in, the spin-out comes.

I am not sure if the underahuling have an effect. The problem is that when I rig it correctly than it will have a sligthly less power and for me it will be even more difficult to get it planning.

The harness lines and boom position:
On my Severne sail the bomm height is about 140cm (on the boom cut-out mark) and the harness lines I do not have exactly in the center of power. I shifted it up to 3cm (max..) backwards towards the leach (it is because I can put the sail more forward into the wind that way and stay a bit more on the back what make it easier for me to enter the footstraps later). And with this arrangement (harness lines a bit back) makes it for me easier to pump the sail which I have to do pretty intensively when the wind is not really strong or gusty.

I am probably too aggresive, and I go fot the upwind direction too early and to fast...but that what makes the sport so nice.

In case this is a technique issue (probably this case) could the bigger fin improve the stability even in the early planning phase (giving me more support). A pro-rider does not need it probably, but I still want to have the fun without spin-out.

PS: The fin choice is what makes the sport really interesting...I like small detailse especially when they affect the ride so strong. I know that the bigger fin will not be so fast as the smaller one and it will also give too much uplift, but it still can be managable...

I know you do not have the feeling that I need a bigger fin, but in the case I go for a new one...what is the option:

freerideflow 500, 520?
slalom 500, 520 or 480 (just the different shape)
freeride swift 500, 520

Thanks a lot.
PS: sorry I am not used to write such a long prose...
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Old 2nd September 2008, 12:01 PM   #4
Ian Fox
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Hi Mim,

From the other discussion the main focus was really on the (very real - but often under rated) importance of draft control in reducing spinout, most especially in hi "load" sailing.

Please try to rig the sail with (at least) moderate downhaul and outhaul settings, rebalance any harness line settings (as these will almost certainly vary in a hi out/downhaul setting mode compared to low out/downhaul) - and re-try the equipment in the 15-2kts you've described. It may not totally cure the problem (especially if you're going for hi upwind angle very agrressively etc) BUT it will almost certainly help quite a bit!

The key here is that you really need to lock the draft movement in the sail firmly (into the ideal /design position) and using low down/out haul can be a disaster in this respect in modern hi tension sails. And although you may think that doing this will cost you alot of bottom end power, it wont make a significant early planing difference (especially the downhaul - unless really OVER downhauled) but it will really help the balance of the whole rig/board/rider under load once planing)and obviously cutting hard upwind at speed tends towards overloading the back of both rig and board- so everything you can do to withstand/delay the draft moving back, the better.) You might even find that the correctly tuned sail is a little easier to actually pump (etc) the whole package onto the plane too - yes, I know this might sound like extra technique required - and might be ! Or add some more sail, like 8.5m but tuned correctly..

Yes, you can try a bigger or different fin as an "easy" solution as well - and while it technically is maybe not the best it is somewhat practical - and easy to try (borrow from a friend / shop etc to try , at least!) In these conditions I would suggest the best mix for ST137/7.0m is not to go too much deeper (as in my experience the ST really doent like to be max/over finned too much) - but rather go for a more efficent upright race fin in 48 (max 50) cm, which is really all you should need in anything like 7.0m conditions.

(I'm calculating your rider weight in the range 80/90kg+) ??

Anyway, please try it and see how you go !

Cheers ~ Ian
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Old 2nd September 2008, 12:59 PM   #5
mim
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Join Date: Jun 2008
Location: Switzerland
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Hi Ian,

I will try what you suggested. I'll rig the sail properly and I'll go to check it in the desired wind range.
You underestimated my weigth a bit I am 95kg, but I suggest that make not a big difference.

the bigger sail is sure what i want to go for...but it's not that cheap and thus easy to get for me.

Just as remark:
I do not think that the sail is etremely under underhauled since there is a loosen leach in each window down to boom. But I will try to downhaul the sail on the recommended luff and let's see.

The last openned question is the mastfoot position:
Somebody told me that that going a bit backwards improve early plannig and top speed. Shifting it forwards improve the upwind property...

is that correct? And what would you recommend (till now I have it half way back)? Should I start with centered position (I guess yes)?

Thanks.
ciao Michal.
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