July 2007

Newsletter, July '07

July 3, Valencia; Team New Zealand loses race 7 and the 2007 America's Cup to Alinghi (Switzerland) by 1 second.

Bloody Hell!!!

After this I'm in no state to do even basic things like continue breathing, let alone writing this newsletter. Being on the road during much of the final series, I didn't get to watch all the races, but did have on-line access to "Virtual Eye", a computer generated real time simulation of the racing which with its extra data on advantage lines, vmg and wind speeds was superior in many ways to TV coverage.  My objective (ha ha) view is that Alinghi had the marginally faster boat- by perhaps 1m in every 200m- but that NZ were the better team tactically. The NZ crew work was also superior in the early races but Alinghi improved to parity in this towards the end. Alinghi eventually won the series because they had enough of a boat speed edge to offset NZ's better tactical decisions, but the 5-2 score line flatters Switzerland and they could conceivably have lost.

So, congratulations to Switzerland- but please don't mention the sailing!- or the rugby for that matter, NZ's "invincible" All Blacks having lost 20-15 to Australia last weekend.

What's the good news then?  Well none, until these black clouds drift away from our national psyche.

But the America's Cup sailing has given me cause to consider fabric life.  While I was at Valencia earlier in the regatta, a comment was made that the performance of an America's Cup class foresail starts to decline detectably after just 10 hard tacks (changes in direction).  One upwind leg or even less!

Fabric life is a huge problem for top level sailors- as it can be for traction kite fliers.  Show kites are not as sensitive as high performance traction kites but their deterioration is more than enough to discourage careful owners from racking up enough hours in the air at events to compete by the kgm-hours measure.*

Which is, of course, begging the question; what flying life can be expected from a maxi show kite?

First of all, a definition; I define maxi kites as those weighing approx. 12kgms. Peter Lynn Kites Ltd scales each new design until it's weight is in the 11 to 15kgm range and defines these as maxis. Dimensions are then halved from this for midi's, halved again for mini's. Like for many standards of measurement this derives from something that's apparently unconnected, in this case airline baggage allowances.  At 15kgms it is possible to pack two maxi kites in one bag and stay under the 32kgm limit that used to apply for journeys to and from the USA. Now the standard bag weight has been dropped to just 23kgms, but the maxi kite definition has stuck. Kites large than maxi's are called super maxi's and (for Guinness record sizes), mega's.

Kites deteriorate because of 2 factors; ultra violet light (which causes degradation of the fibres, coating and dyes) and the km's run of wind that pass them, weighted towards stronger conditions. Generally for this though, I use the cruder measure of days flying.  Thrashing wind causes coatings to flake away, increasing porosity (but which, paradoxically, increases tear strength). It also abrades adjacent fibres eventually reducing fabric strength.

In my experience, actual damage doesn't cost kite life. It may, for those who are concerned with intangibles, make a kite less desirable to own but it won't effect its life and, after repairs, won't significantly effect the kite's appearance while flying. In a lifetime of kite abuse, the most serious damage I've ever done has taken little more than a day in the factory to repair- which is equivalent to less than 10% of it's value when new.

I have seen kite fabric fall apart because of UV, but with reputable fabrics, this takes perhaps 1000 or more hours exposure.  Much more rapid- and more annoying, is colour fading.  Fluoros are the worst- stay away from them for display kites that need to last, no matter what the graphics temptations are. Some other colours are also susceptible to fading, usually the lighter colours like yellow. There is no predicting this except by experience or actual testing- every fabric type from each manufacturer has it's own quirks. It's also useful to consider where a kite will be flown. In Australia or NZ, some colour fade can be detectable after just a week's flying, whereas the same kite would not show any signs until after at least a month or more in Europe (even in the Mediterranean).

I now find that the useful life of a maxi show kite is more than 300 flying days. At this it will still generally be presentable and suitable for all winds. Even just a few years ago, perhaps 150 flying days was the tipping point.  This gain has come from developments in construction and from the use of better fabrics, particularly those combining polyurethane and silicon in the coatings- usually at about an 80/20 ratio. This fabric stands wind damage better, appears to be generally more colour fast, is much more resistant to tearing and is easier to pack than harder finishes.  It's also water resistant. 

On a straight line depreciation basis therefore, each day of flying now costs a maxi kite owner  about NZ $25.  A typical 9 day event with 4 kites up for 8 hours per day costs $900.- and scores 480 kgm-hours/day, which is what I strive to hit when conditions allow.

Peter Lynn, San Fransisco, July 3 '07

* the kgms of fabric in the air multipled by the number of hours it remains there, per person.