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Another question, spinnakers , alt/assym/sym |
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Sam.Spoons
Really should get out more Joined: 07 Mar 12 Location: Manchester UK Online Status: Offline Posts: 3398 |
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Topic: Another question, spinnakers , alt/assym/sym Posted: 17 Feb 18 at 1:56pm |
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I do it quite often in the Spice but, obviously only in the lighter stuff (I can get wiring in 5 or 6 knots with 16 M2 up the stick, add a 22 metre kite and I can stay wiring downwind in similar). TBF the Spice is pretty docile sub F4 so gives a pretty stable platform. Coming from windsurfing you'd think it would be second nature but without the boom in your hands it's a bit like tightrope walking without a pole. It's not that hard though and while the Farr will be a bit more lively I'm sure you'll manage (and it's damn good fun).
Edited by Sam.Spoons - 17 Feb 18 at 1:57pm |
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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish" |
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turnturtle
Really should get out more Joined: 05 Dec 14 Online Status: Offline Posts: 2538 |
Post Options Quote Reply Posted: 18 Feb 18 at 1:20pm | |
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Rupert
Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
Post Options Quote Reply Posted: 18 Feb 18 at 4:37pm | |
Are you sure adding 12sq m of sail really only once 3 or 4 points off the handicap? That would suggest that either they are almost useless or that your prediction programme has a glitch. I'll go with the latter.
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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JimC
Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6649 |
Post Options Quote Reply Posted: 18 Feb 18 at 5:14pm | |
Spinnakers do make surprisingly little difference. But then when you analyse it in detail...
Supposing on a notional course you spend 100 minutes of your time beating, 30 mins reaching and 20mins running. (I'm making all these numbers up BTW) The extra windage, weight in the ends and up the mast etc make the boat 1% slower upwind, so you now spend 101 minutes beating. A run is a run, and it doesn't make that much difference how much rag you put up because each increment in speed is less apparent, so lets say 5% faster, thats now 19mins running. Finally we go 50% faster on the reach, which would be pretty impressive, so what, 20mins reaching. Total time round the course 140mins instead of 150 mins. What's that, under 10% faster round the track for 50% increase in reaching speed... |
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Sam.Spoons
Really should get out more Joined: 07 Mar 12 Location: Manchester UK Online Status: Offline Posts: 3398 |
Post Options Quote Reply Posted: 18 Feb 18 at 5:24pm | |
That sounds about right. FWIW I did some sums using the Int Canoe and Assymetric Canoe as examples as the old IC's had the same hull as the AC does now. The 2017 PN's are 893 for the IC and 866 for the Assymetric Canoe. Bearing in mind the IC has been a development class (with the all up min weight reduced from 87kg to 50kg) since 2009 after many years having a one-design hull while the AC has retained the one-design hull. The CA are suggesting pre 2009 ICs (with the same hull as the AC) have a PN of 920. That suggests that the difference the kite makes to the IC is nearly 6% (or roughly 10 mins in a 150 min race). The IC has a standard rig of 10 M2 and the kite is only limited by the mast and pole lengths, apparently most are around 23 square metres. That's still 54 points though not 3 or 4.......
Edited by Sam.Spoons - 18 Feb 18 at 5:28pm |
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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish" |
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Rupert
Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
Post Options Quote Reply Posted: 18 Feb 18 at 9:23pm | |
Under 10% I can well believe, and less for a boat like a Feva, which would struggle with the 50% reaching figure. Less than 1% would suggest a totally unsuitable hull form, maybe a displacement class where adding more sail simply puts pressure on everything. The Farr 3.7 certainly isn't that, even if it lacks the length and righting moment of the IC.
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Sam.Spoons
Really should get out more Joined: 07 Mar 12 Location: Manchester UK Online Status: Offline Posts: 3398 |
Post Options Quote Reply Posted: 19 Feb 18 at 9:26am | |
Yup, maybe more on long open courses and less on a river.
Any way you look at it on a planing hull adding 150% extra sail area is going to go more than 0.4% faster.
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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish" |
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JimC
Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6649 |
Post Options Quote Reply Posted: 19 Feb 18 at 10:16am | |
That was meant to be an extreme value. I very much doubt there are many classes that go 50% faster with the kite up. |
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Dougaldog
Far too distracted from work Joined: 05 Nov 10 Location: hamble Online Status: Offline Posts: 356 |
Post Options Quote Reply Posted: 19 Feb 18 at 11:07am | |
Jim C - I know that the IC scene is not my 'specialist subject' so the view I expressed in the reports were really just what I was seeing for myself, first hand. But after spending 10 days + out on a RiB in Tremadog Bay reporting on the IC pre-worlds/Worlds, I was more impressed by the performance of the new design ICs than I was by the ACs. With the exception of one day which was very light, most of the racing was conducted in what could best be described as a 'good breeze' and whilst the ACs were undoubtedly quick in a straight line downwind, the gains they made seemed to be wiped out heading back upwind. There were also big losses in time when hoisting and recovering, as many of these were accompanied by a swim or two...... I couldn't make a direct one on one comparison as the ACs did w/l whilst the ICs did triangle sausage and I stress again - I was looking at this as an 'outside reporter' but the performance of the Maas boats, Dragonfly and the Morrisons was - eye catching! D
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Dougal H
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JimC
Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6649 |
Post Options Quote Reply Posted: 19 Feb 18 at 11:15am | |
The new ICs and the ACs seem to be reasonably level round the racecourse. But a typical fleet of anything seems to be around 20% front to back, so its very hard to make comparisons.
Edited by JimC - 19 Feb 18 at 11:18am |
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