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Old 18th December 2015, 08:32 AM   #1
Mattsurf
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Default Isonic IS90 get the right fin

The IS90 is possibly the most fin sensitive board I have ever used - get the wrong fin and the board doesn't gybe well, and doesn't feel at all comfortable at speed.

Following Remi's advice on this site, I bought a range of Drake R2R DW fins; 30cm, 32cm, 34cm and 36cm. Overall I have been very pleased with the fins. However, I would make the following observations; I almost always use one fin smaller than the recommended size for the sail and it really improves control and gybing to use a smaller fin in this board.

Recently the wind has been pretty epic - I have been using 5.2m and 5.7m race sails for my past 4 sessions in winds consistently over 30kts and gusting well over 40kts. I have been immensely impressed by the board in winds right at the top of its wind range; using the smallest 30cm fin, I have had no control problems, maybe it is because I am now familiar with the board, but I am confident pushing to go as quckly as possible.

In summary, the IS90 is a wonderful board, but only if you get the right fins
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Old 18th December 2015, 07:12 PM   #2
Marko CRO169
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What other fin size - sail size combos have you found as best?
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Old 18th December 2015, 09:51 PM   #3
Mattsurf
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Quote:
Originally Posted by Marko CRO169 View Post
What other fin size - sail size combos have you found as best?
5.2 is excellent with a 30cm R2R
5.7 goes well with 30cm R2R
6.3 goes really well with a 32cm R2R
7.0 goes well with the 32cm or 34cm R2R
7.8 is surprisingly nice with 36cm R2R

I weigh 85KG and 175cm tall
my sail selection - North WARP F2013
winds gusting 36kts+ 5.2
Winds gusting 32kts 5.7
winds gusting 28 kts 6.3
winds gusting 23kts 7.0

2 second v-max speeds in small chop with 6.3, 5.7 an 5.2 always around 36kts

My favourite sail on the board is either the 5.7 or 6.3 as they pin the front of the board down better than the 5.2, but now getting more used to the 5.2 setting the sail 2cm further forward and raising the boom a little helps pin the board down in mega wind

Just changed sails to 2015 GA Vapours for 6.3 and upwards - but not been on the water yet due to using 5.2 and 5.7 all the time!
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Old 21st December 2015, 11:33 PM   #4
mark h
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Hi Matt,

Which year is your is90 and wood or carbon? The is90 is the only board that I might be tempted to change my beloved W58 for?? I have seen a few impressive is90 speeds posted on gp3s.com so it's certainly a fast board.
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Cheers - Mark H

The toys:
Speed W44 - Speed W49 - speed W53 - speed W58 - iS76 - iS107 - iS130 - F161.
North Warps: F2012/F2013 5.2m, 5.7m, 6.3m, 7m, 7.8m, 8.6m, 9.6m, F2006 11m.
F-Hot fins (slalom). Tectonic Nomads (speed)

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Old 22nd December 2015, 08:05 AM   #5
Mattsurf
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Hi Mark, I have the 2014 Is90 carbon. Speaking to other people with the 2015 board, the characteristics are pretty similar, and both 2014 and 2015 board are equally fin sensitive

I have yet to use it in perfect speed conditions, however, it does feel very quick - hitting 2s peak speeds of 35-36 kts is pretty easy with 6.3m, 5.7 and 5.2m sails.... however, I am not getting faster speeds with the smaller sails, however, I suspect that is more down to technique and lack of practice on the small stuff.

I had the Is87 wood before and initially found the Is90 alarmingly quick/difficult to control - but that may have had something to do with the Vector Rockit 32cm fin that did not suit this board at all (and it was a beautiful fin on the Is87).

In one respect that Is90 reminds me of my old 1998 Thommen 270; when sailing broad it has incredible directional stability - when sailing under full power I find it almost impossible to bring it back up wind without sheeting out. last weekend, a kite surfer came upwind accross me as I was overtaking on a broad reach (technically he was entitled to do this) - I found it impossible to take avoiding action and went straight into the back of him

I have no doubt that the Is90 is quicker than the Is87 wood, however, my personal vmax is still 36.9kts on a 6.3 on the Is87
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