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PY adjustment for non-spin Mirror or Cadet
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rich96 View Drop Down
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Posts: 596 		Post Options Post Options   Quote rich96 Quote  Post ReplyReply Direct Link To This Post Topic: PY adjustment for non-spin Mirror or Cadet
    Posted: 04 Sep 22 at 2:25pm
To be fair you cant really compare that the effect of that horrible bolt on kite that they put on a boat that was already a handful (2 sails plus sliding seat on a single hander) to taking away a kite from  say a 400 (a 2 man boat designed to have a kite originally).

The AC inevitably died.
















Edited by rich96 - 04 Sep 22 at 2:26pm
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Paramedic View Drop Down
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Posts: 929 		Post Options Post Options   Quote Paramedic Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 22 at 3:30pm
The AC died out here but I believe its still going in the USA and Australia where they have the water to make it work.

But I agree with the sentiment, take the kite off a Fireball, Scorpion, Merlin, 400 or anything moderately fast that sails reaches and runs and its crippling, way more than 4%
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 22 at 6:38pm
In fact the UK was the only country where the AC got much of a following. Not, in my opinion unconnected with the fact that only the UK had Rob Michael.

There's very little useful real data available for kite versus no kite, but I note in Australia the difference between an NS14 and a MG14 (same rules except for a kite on the MG) is about 2%.

As a crude calculation to achieve say 10% faster round the cans on a boat that's normally say 25% faster through the water downhill than up the downhill speed needs to increase by about 40%. If we are talking about a pole kite boat that runs dead downwind such an increase is unobtainable on the run.

Edited by JimC - 04 Sep 22 at 6:48pm
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Rupert View Drop Down
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Posts: 8956 		Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 22 at 9:07pm
Given that PY is an average of all wind speeds, including too light to fly properly and too strong not to swim, plus all points of sail, the advantage of the much higher speed on a perfect reach in perfect wind is heavily outweighed by other factors.

I remember a race in a 2000 where we had 2 amazing reaches where we planed, gybed, planed flat out every lap, and beat all the single handers by a country mile. Balance that against all the races where I've been soaking low and being thrashed by Lasers down the run, and I can see why on average it makes little difference. Good game, though.
Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Paramedic View Drop Down
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Posts: 929 		Post Options Post Options   Quote Paramedic Quote  Post ReplyReply Direct Link To This Post Posted: 05 Sep 22 at 7:20am
I fully accept that a boat without a kite isn't going to get round the course at half the speed of the same boat with a kite. But unless its too light to go sailing it does make a significant difference and a symmetric most definitely gets your down a run faster than not having one, whether you sail it in two reaches or soak down.

We all strive for an extra 0.25% boatsepeed, 1% is very significant but I would suggest 10% without a kite is a decent guess for round the cans in a medium speed symmetric boat - that's 6 minutes in an hour. Obviously water size and windspeed comes into this too but I think in medium conditions on a decent course at my club i'd struggle to finish within 5 minutes of myself if I didn't use a kite - 5 minutes is probably 1/4 - 1/3 of a lap including a beat.

If you're sailing an inefficient assymenteric (Slower than a 400) the more running time you have the less difference it makes.


Edited by Paramedic - 05 Sep 22 at 7:21am
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seastate View Drop Down
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Posts: 4 		Post Options Post Options   Quote seastate Quote  Post ReplyReply Direct Link To This Post Posted: 05 Sep 22 at 9:25am
If sailing with a symmetric kite on a big course dead down wind is slower than coming up about ten degrees and gybing on the shifts. Soaking dead down wind only works on a very short leg or to do the last few metres on a big course without having to do two gybes.
Asymmetric kites will work downwind in lighter winds as long as there is room to sail where you want and gybing on the shifts, restricted waters or where there is a strong tide dictating where you go is when it fails.
I don’t even sail dead down wind in my current stead ( a single handler with shrouds) as sailing a bit higher and gybing on the shifts proves to be quicker.
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Posts: 3011 		Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 22 at 1:48pm
Originally posted by JimC

In fact the UK was the only country where the AC got much of a following. Not, in my opinion unconnected with the fact that only the UK had Rob Michael.

There's very little useful real data available for kite versus no kite, but I note in Australia the difference between an NS14 and a MG14 (same rules except for a kite on the MG) is about 2%.

As a crude calculation to achieve say 10% faster round the cans on a boat that's normally say 25% faster through the water downhill than up the downhill speed needs to increase by about 40%. If we are talking about a pole kite boat that runs dead downwind such an increase is unobtainable on the run.

The speed difference around the course is anything from 'next to nothing' up to 'twice as quick down wind, so about 15 or 20% overall.
If the kite means you plane and the others don't you're quids in.
If it means you can overtake on a dead run, it puts you clear ahead up the next beat.
Small changes in actual boat speed can sometimes be magnified by mark roundings and tactics.
Other times, a significant boost in speed down the reach doesn't make up for e.g. being a boatlength behind the leader at the first mark.

Sometimes in light air, not faffing with the kite is faster.
I once broke the kite halyard on a 400 early in a windy race, I don't think it changed our finishing position at all.

Years ago at a small inland club, we used about 2%, it worked as well as anything else.
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