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Old 22nd January 2007, 02:28 AM   #1
jeroenmarcia
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Default iSonic 115 tuning (for Ian)

Hi Ian,

I Have an iS 115 for one year now. I Use it with RS6 8.4 and 7.2 and i weight 80kg and use the standard fins supplied with the board.

I use 26 inch lines and sail on a lake which can be choppy from time to time.

42 fin with 8.4
34 fin with 7.2

Can you give me some recommandations and tips about tuning this board in combination with these sails and my weight ?

- Footstrap positions ?
- Mastfoot position ?
- Other fins (brand, size) ?

Thank you for you answer,

Jeroen
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Old 23rd January 2007, 06:19 PM   #2
Ian Fox
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Default RE: iSonic 115 tuning (for Ian)

Hi Jeroen,

I guess the first comment is that the ST115 is not really the "ideal" board for tuning with a powerful 8.4m like the RS6. Yes for sure it's sailable with bigger fins and sails - but it's definitely taking the ST115 well outside the typical (6-7m) sweetspot range for that model.

Outboard slalom straps settings will be generally prefereable wth both these sail sizes (as well as matching the sail type to sailing style/stance) - in lighter and flatter conditions you will squeeze a little more top end from the board with the outboard rear straps, but ionce the wind and chop is up, one position FWD (Front and Rear straps) generally allows the rider to hold a more calming stance over the ST while still keeping a good amount of drive/power going thru the board.

Mast track for 7.2m would be typically 50-60% FWD, for the 8.4m the same, or a little further forward could help induce a little earlier planing, but in general don't go too fwd with the mastfoot to maintain a good combo of speed and free, responsive ride. If the board is really starting to fly away (too much fin/sail/chop) then moving the track forward more can help, but it's not really curing the problem efficently, rather just an interim dampener to get you thru..

Fins depends a lot on the ride style you're seeking; it's definitely valid to run race or slalom fins on the ST (especially when the sail choice doesn't really assist in SuperX or freemove style riding) and you wil definitely find the more upright race fins more efficent (for a given size), help a little in holding ST efficency when running tight upwind etc and/or marginal conditions and genarlly well behaved in speed in straightline, but the race fins don't quite maintain such an "easy" handing thru the jibes etc as the more raked freemove/freerace type fins. Sizes in turn vary a little with the fin (make / model) but for powered 7.2, a 34 is a good typical size (think range 32-34-36); for the 8.4, well I really try and keep a smaller fin on the ST115, so for that maybe consider to try a race fin around 40cm as a good allround option. 42 is definitely possible, but again well past the ideal sweetspot for ST115. (in a lot of ways, you are tuning the ST115 much more like an iS115/111, which would probably meet this sail size range better than the the ST).

Anyway, it's about having fun and hopefully you are getting plenty!
let us know if you want more info.

Greetz ~ Ian

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Old 23rd January 2007, 07:01 PM   #3
Meindert
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Default RE: iSonic 115 tuning (for Ian)

Hi Ian,

In you're reply you mainly talk about the ST115? Is this a type error?? Because Jeroen is talking about a iSonic 115....
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Old 24th January 2007, 03:47 AM   #4
Erich
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Default RE: iSonic 115 tuning (for Ian)

for sure it's no typing error because all that was said in Ian's reply referes to the ST 115 (if I'm not totally mistaken). Obviously Ian mixed up the St 115 with the IS 115 in the original post.
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Old 24th January 2007, 08:28 PM   #5
Meindert
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Default RE: iSonic 115 tuning (for Ian)

Maybe Ian could tell us something about tuning the 2006 iS115 with RS:6 8.4 and 7.2??? (i have the same combo)...

Thanks Ian!

Meindert
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Old 25th January 2007, 04:36 AM   #6
Ian Fox
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Default RE: iSonic 115 tuning (for Ian)

Now there's a mistake ! Please accept my apologies, Jeroen (and others), that was definitely a iS vs ST mix up on this one.

So, to talk about the iS115 with 8.4/7.2m..

(Actually, that is even an easier reply, too !!)

Footstraps : For 8.4m lightwind speed, and as long as you don't experience any major control issues over chopconsider to use the very back positions on the Front and Rear straps (subject to height/strap pitch). For really powered or choppy 8.4 and most 7.2 conditions, you will likely find the mid strap position a more verstaile setting as it allows a more "calming" stance over the board thru the chop, which is usually no less speedy (often more..) but in most cases easier for the rider to stay on the power - and in most cases gives a more fluid jibe with a more engaging action on the rail in the entry/mid jibe.

Mast track. For 8.4m speed, you can use 50-60% forward (this one depends also on the rider height/boom height, so don't be worried if your ideal seems a little one way or the other, but in general the basic mid position is still close to the best for 8.4, and definitely for 7.2m, the mid (50%) or even just behind if you really want to tweak for more top end speed (if the water/chop allows for that). Again, in both cases if you are REALLY struggling for control, it's ok to force the situation by moving the foot 1-2cm forward, but in general (if everything else is close to good) it should not be necessary.

Fins : Typically using more than 42cm doesn't add significant early planing, and becomes quickly a law of diminishing returns when considered against top end speed and control (which usually suffer noticeably above 42cm).

It can definitely be worth considering a smaller fin for powered 8.4m conditions, as well as a larger fin for "marginal" 7.2 conditions - in this situation the size choice can also be influenced by "practical" factors. One additional fin at 38cm would cover the "overpowered" 8.4 conditions, as well as doubling for "marginal" 7.2m. For pure downwind or speed in powered/overpowered 7.2, you can consider a 32cm, but keeping in mind the mid size iSonics generally perform best with a moderate (not excessive nor too minimalist) amount of fin for the conditions. Of course, it's possible to go crazy and have every fin at 2cm gap, which is nice - but in most cases excessive. The stock sizes are very capable and in typical sailing range well spaced to cover most of the effective range of the board/s quite well.
Make and model of fins is influenced by rider style/preference, as well budget and availability, but in general for iS in this range look for medium stiff fins (in this size range), with fast foil profile and low rake angles.

Hope this clarifies it, but don't hesitate to contact us for further info or questions.

Cheers ~ Ian
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Old 8th May 2007, 03:12 PM   #7
Meindert
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Default RE: iSonic 115 tuning (for Ian)

Hi Ian,

Thanks for your reply and apologies accepted off course! Happy you're helping me (us) out. I now have some sessions with the iSonic115 and
RS6 8.4. I had one problem when sailing this combo. My front foot will
not stick in the footstrap. It is not a nice feeling.

I have tried the following:
- Lower the boom
- Masttrack 1cm to 2cm before the middle

This helped, but not sufficient, so tried to narrow the stance:
Rear footstraps in the middle and front footstraps in the back.

This helped, but when the wind is increasing the problem is coming back.

How can i solve this ? Wil a smaller fin help (i.e. 38 cm) or can i
solve this by changing my technique ?

Can you advise me ?

Thanks Jeroen
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Old 23rd May 2007, 11:38 PM   #8
jeroenmarcia
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Default RE: iSonic 115 tuning (for Ian)

Quote:
Meindert wrote:
Hi Ian,

Thanks for your reply and apologies accepted off course! Happy you're helping me (us) out. I now have some sessions with the iSonic115 and
RS6 8.4. I had one problem when sailing this combo. My front foot will
not stick in the footstrap. It is not a nice feeling.

I have tried the following:
- Lower the boom
- Masttrack 1cm to 2cm before the middle

This helped, but not sufficient, so tried to narrow the stance:
Rear footstraps in the middle and front footstraps in the back.

This helped, but when the wind is increasing the problem is coming back.

How can i solve this ? Wil a smaller fin help (i.e. 38 cm) or can i
solve this by changing my technique ?

Can you advise me ?

Thanks Jeroen
Hi Ian,

Can you please give a reply on the question above ? Has the problem of the front foot anything to do with length of people or more specific length of legs ?

Many thanks,

Jeroen
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Old 24th May 2007, 05:23 AM   #9
John1
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Default RE: iSonic 115 tuning (for Ian)

Hi.
I have a lot of experince with that as an owner of SB HS.

-Lower the boom
-More Downhaul
-more Outhaul
-Masttrack a bit forward
-Move the front footstrap a bit backwards, more power on the frontfoot

And the most important parameter:
-A sail with stable deep forward, draft profile

With regards,
John J
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Old 24th May 2007, 07:00 AM   #10
Ian Fox
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Default RE: iSonic 115 tuning (for Ian)

Right... As JJ has correctly noted, the usual cause of the front foot slip is an imbalance in the weight/load distribution betwwen the two feet (even if at the time it may not initially feel like that).

The typical telltale is the footslip trend increasing as the wind/power comes on (especially if the rider remains on the one sailing angle- for example beam reach B&F). In this case, the main "change" has been the increase in rearfoot pressureas the rider sheets harder on the backhand to compensate the extra sail load- but more importantly if the sail draft stability moves back under the increased load, the balance of the rig also moves aft and the whole trim has become not as balanced/centred.

Adding extra downhaul (beach trim) helps lock the draft forward and low, while adding extra outhaul (both beach trim or more importantly actively using a variable outhaul on the water) will help a lot in keeping the rig as balanced as possible for the conditions.

This is particularly important in lighter (big7-9m) conditions and with mid to larger slalom boards where the rider may experience a wider range of dynamic loads on the sail as they go from marginal conditions (light-moderate loads when the board is subplaning or at planing threshold ) to quite hi apparent wind loads when fully planing (in not too many more actual knots windspeed). In these conditions, the water can often be quite flat (minimal wind chop) which also allows for quite fast (c/w rougher conditions) open water speeds, so the total dynamic apparent (vector of the actual wind plus board speed) loads up the rig a lot more than sailing "slow" in the same actual windspeed.

On the water, modern slalom gear is more capable than just about any other style of equipment for changes in sailing angle (pinching hi upwind vs beam reach B&F vs broad downwind/speed) - also with resultant changes in overall apparent wind sail loads, and these changes also obviously effect the optimum sail trim - another compelling vote towards fitting and using a really effective variable outhaul in "big" slalom conditions more than about any form of sailing (except FW).

Noting also that often in modern 7-8+ m slalom conditions, the actual wind may be "light" or quite powered" for the same equipment, so a corresponding range of sail tune is more important (and more likely) than, say, in more always powered conditions when using a more standard (one trim fits all) sail tune may be more applicable.

This really be came apparent when the HS released, as a lot of people from other styles of windsurfing suddenly experienced this subtle but real difference of (relatively) high speeds in light/er) wind conditions.

Yes, you will also get a change/improvement by varying the other stance factors, (and ultimately some refinement of those may also be ideal) but predominantly (if your stance was initially correct/optimum) you are then dealing with the results (imbalanced stance) rather than curing the cause (imbalanced rig). In most cases, getting the ideal balance in the rig for the conditions will help improve your sailing and range quite a lot - and at least with the primary issue of the rig under control, the rider is then at the best position to fine tune their stance.

Rider height and leg length will ultimately factor into the best effective stance (strap pitch / boom height /harness length + hook height etc, )but again the level of variance based on leg length will be relatively minor in overall trim unless the rider is exceptionally tall (or short) or of very unusual leg length vs overall height.

Hope this helps solve the problems and gets you flying ~
.. across the water rather than into it !

Cheers ~ Ian
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