Old 21st August 2007, 04:11 PM   #1
ned_321
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Default GPSSS - iS76 vs iS87

What (if any) is the advantage of iS76 over iS87 for GPSSS speedsurfing?
I want to improve performance in the windrange 6.2 SqM and smaller. Compared with the iS87 the iS76 is smaller overall, but the tailwidth is larger (!!!).

I already read these threads, but do not want to "pollute" them:
http://www.star-board.com/forum/showthread.php?t=2429 (101 or 96)
http://www.star-board.com/forum/showthread.php?t=2521 (76 vs 52)

I currently have the iS87 and am very pleased with it. I had the iS50 for while before (combined with S95 for less windy days).
But IMO the number of “ideal” days for this board is too small for practical useage at real-world spots (mostly Strand Horst NL in my case). And for some strange reason that small number of “ideal” days seems to coincide with non-moveable work obligations.

Topspeed and acceleration of iS50 are very good, but not good enough to compensate for slow starting speed at the beginning of the 10second run.

So I changed iS50 for iS87. Since then put all of my PB’s on the iS87 (69.14 average / 74.2 display). So why change a winning team?

When I got the iS87, there was a “hole” in the range between the iS50 and iS87. I would have preferred a board a bit smaller. I am NOT interested in running anything larger than 6.8 on my smallest board; I have a iS101 for lighter winds.

But now there is something between the iS87 and iS50: the iS76.
The question is: is this board a significant improvement over the iS87 for GPSSS speedsurfing?

I am interested in improving GPSSS performance in the windrange 6.8 and down. Mostly used sailsize is 6.2, and ofcourse smaller than that for really windy conditions.

What worries me a bit is the trend towards wider and wider tails. This is nice for average speed (buoy to buoy) but not beneficial for all-out speed (GPSSS). Generally speaking this favors massive sailpower to generated speed, and defavors “glide”.

This started in the larger iSonics; but now also is happening at the iS76.
Tailwidth of the iS86 is a full cm wider that the iS87.
And tailwidth of the iS76 is still larger (0.3 cm) than the iS87 (!!!).


I am considering to change the iS87 for the iS76.
But the increase in tailwidth (0.3 cm wider c/w iS87, for a smaller board) makes me doubt. Is the iS76 also a "victim" (from a GPSSS point of view) of the trend to favor average speed over topspeed?
Other shape details to compensate for tailwidth effect?
How do iS76 sailing characteristics differ from iS87?
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Old 21st August 2007, 07:12 PM   #2
Ian Fox
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Hi Menno,

One of the clear feedback messages about the iS87 in GPSSS use is how effective and accessible this board is to use for speed racing. This has been openly proven and complimented by some well known riders, including some not associated with Starboard like Martin van Meurs. Your own experiences and PB's indicate just how practical a board iS87 that can go, and maybe concerns about accessibility to conditions to make best use of a full blown design like iS50. But of course we all want to find ways to make better results - and take it (speed) to the next level.

As you know, that extra couple of kts of top end on GPSSS doesn't come so easy, and suddenly each of the little factors become significant. So to improve the new iS for GPSSS use (and for this discussion ignoring it's other design role/s as an extreme hi wind big rider slalom board, and/or a mid-hi wind slalom for lighter riders), one of the key criteria was to retain as much of the positive of the iS87 and yet find ways to improve the top end speed/control potential. Really what is delivered in the iS76 is a iS87 tail block with a slightly improved (top end) tail rocker married to a smaller, narrower overall but still very practical and safe front and mid section. Considering the sweetspot for GPSSS speed use is around 5.5-6.5m, this will be a very competitive "big" board in anything below "record" (iS50 ??) conditions on Horst etc.

Current hot buzzword around speed discussions at the moment is "efficiency" and the iS87 is big in that. In iS76, it potentially can be even higher.. Glide may not be so irrelevant in aiming for hi efficiency top speed runs and strangely enough even "average " speed should not be discounted, especially if you are looking for the magic 500m where in 20 seconds a lot of "averaging" factors come into play. Or 5 x 10 where you need a good 5 solid runs to make the average, and one blinder can be washed away with 4 other "average" runs.

So your question " is this board a significant improvement over the iS87 for GPSSS speedsurfing?"

Answer : Depends how you define significant. For an 88 kg rider in marginal GPSSS conditions, iS76 may not represent a significant improvement over iS87. If a GPSSS meet was held and decided in marginal conditions, then for a heavy guy, switching to iS76 might not give any advantage at all. But as conditions improve, for that same rider who had reached close to the practical limit of something a little larger (like, say iS87) and wanted the potential to take his GPSSS results higher, while still retaining a serious amount of the "practical" side that the iS87 has proven, then yes, it could be considered to be reasonably significant. And the significance of that is that it is much more likely that the rider has an even better chance to raise his/her PB higher when it's iS76 sweetspot conditions than iS87.

Same question asked another way : On a GPSSS PB day will iS76 have a significant chance to improve PB over iS87 ?

Answer : Yes.

Same question asked another way : Would it be be easier to do a 40.0kt 5x10s on iS76 than iS87?

Answer : Yes.

I am sure that very soon Martijn will have the first samples in Holland, and the speed meets will be a very good place to put the test.
We look forward to the results.

Cheers ~ Ian
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Old 9th September 2007, 07:29 PM   #3
martin van meurs
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Hi Ian,

The IS87 is a very nice board indeed. With a topspeed of 44,4 and a 500 meter of 41,7 (record on Dutch waters) with a TR3 6,3 and a Boogie Z30 fin this board proved to be pretty quick indeed. It most certainly is one of my favourite boards. I am really looking forward to give the 76 a shot at strand Horst to see if it's even faster. As soon as Martijn recieves the new boards I will give them a fair test.
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Old 14th September 2007, 05:06 AM   #4
Grant
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With a potential top speed of 44.4 knots who needs anything faster than the 87 ·(recreational sailors that is)? Those speeds Martin has achieved are simply amazing! I am pushing my speed limits with this board now - best so far is 35.56 knots in small chop (breaking 40 m.p.h. has been a goal of mine). If I can find some really flat water and big wind I am really going to push it and this board gives you the confidence to really try hard - a big plus! At 35.5 knots the board feels like it's in fourth gear with two more gears to work through - definitely a very fast and a very practical fun board.

Cheers,

Grant

Last edited by Grant; 14th September 2007 at 05:11 AM.
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