Author Topic: Relative speeds...  (Read 3069 times)

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Offline JimC

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Relative speeds...
« on: November 21, 2014, 03:58:13 PM »
I've been asked to write something on handicap racing for the Canoe nbewsletter (dunno why me, I never manage to win any races) and it occurred to me that a useful point of comparison would be with the Cherub as regards relative performance on courses etc. Trouble is my days long predated GPS logging, so I'm not entirely sure what numbers we really did.
In the IC, on a lightish airs day, I seem to run at around 4 or 5 knots upwind, 5 or 6 deep downwind, and around 9 or 10 crosswind (the old one design hull seems to top out about 15). Which is interesting in itself, because if you asked me I'd have said that the beating was faster than the runs, but the GPS says I'm wrong.
Anyway, obviously the Cherub is going to be very very different, and I'm sure some of you have done enough GPS logging to be able to give me some ideas about what the relative numbers are. Any thoughts?

Offline Clive Everest

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Re: Relative speeds...
« Reply #1 on: November 21, 2014, 05:13:17 PM »
Hi Jim,
We used to have great fun racing the 600s against the Canoes at Hayling back when there were a lot of each.
We would swap places every leg and the result was never clear until the finish.
We were sailing off scratch handicaps.
Racing another 600 was boring. A 3 boat length lead was safe.

It was a similar story racing 14s against FDs at Eastbourne. If they were at the gybe mark on a triangle course as we went round the windward mark we could catch them.
They could do a beat and a very slow reach quicker than we could do a beat.

For the Cherub performance there is some good data from Trackers on the club web sites for the Datchet Flyer last year and the QM open.
The QM data has more boats but the trackers were very unreliable and the wind varied between 5 and 20 kts with 40 deg shifts.

In a decent breeze we were doing 7-9 kts upwind and 12-18 downwind.

The Ellway paper on designing the E5 has some good data as well, recorded from the Lee's sailing Atum at the nationals. From memory he estimates that a cherub will do 0.7 x TWS upwind and 1.2 x TWS downwind up to about 15kts of wind.
The new boats are less on - off. markedly faster upwind in light to medium and downwind in light conditions. In a blow a slug is still fast.

Clive

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Offline Will_Lee

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Re: Relative speeds...
« Reply #2 on: November 25, 2014, 09:48:43 PM »
This 2007 nationals report ( http://www.uk-cherub.org/doku.php/news/20070722 ) links to a lot of the GPSAR tracks of the races. Dont know if the links work any more.