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PY / Top Speed formula? |
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Mark Jardine 
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Joined: 12 Mar 04 Location: Milford-on-Sea, United King Online Status: Offline Posts: 1028 |
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 Topic: PY / Top Speed formula?Posted: 13 Mar 13 at 2:35pm |
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Hi all
We're looking at starting a new competition, like the old 'Speed Freaks' which we last did in 2007, but I'd like to normalise the top speed according to the PY of the boat. I'm wondering if anyone (well, specifically I'm thinking of JimC, Peaky and Daniel Holman off the top of my head) could come up with a formula which would normalise theoretical top speeds to give a 'score' when an average speed over 30 seconds was entered. I of course know that this isn't going to be 100% equalised, and some boats will be treated better by any formula we create, but it would be a great basis for a 'fun' competition (with some very good prizes) if we could do it! I might well have a solution to getting reliable GPS data over 30 seconds, so don't worry about that bit. Many thanks in advance! Cheers, Mark |
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JimC
Really should get out more
Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6662 |
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Posted: 13 Mar 13 at 4:09pm |
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Well, I guess you want to convert speed in knots into time to do a nominal distance so that's what, (60/V) * 60 to get the distance to do a nominal nautical mile in seconds if my brain hasn't turned to mush.
Then treat the resulting number with the normal PY formula of ET/PY*1000 = CT to get a corrected time. Finally convert corrected time back to knots to get a corrected speed, so, that's, what, 3600/CT. So 3600/((((60/V) * 60)/PY)*1000) Now that formula can be considerably simplified, but I'll leave that as an exercise for the next poster (grin) Edited by JimC - 13 Mar 13 at 5:15pm |
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Rupert
Really should get out more
Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
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Posted: 13 Mar 13 at 4:26pm |
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Sounds like fun - but then I own a slow boat that is rubbish upwind but is a flying maching on a really windy reach - now I just need to move into the 21st century when it comes to things like GPS...
As for the next poster simplifying the equation - next, please! |
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Bootscooter
Really should get out more
Joined: 15 May 07 Location: United Kingdom Online Status: Offline Posts: 1094 |
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Posted: 13 Mar 13 at 4:35pm |
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*stares blankly at screen*
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tgruitt
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Joined: 02 Dec 04 Online Status: Offline Posts: 2479 |
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Posted: 13 Mar 13 at 4:37pm |
My brain has fallen off. |
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Needs to sail more...
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alstorer
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Joined: 02 Aug 07 Location: Cambridge Online Status: Offline Posts: 2899 |
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Posted: 13 Mar 13 at 4:41pm |
CT= V / (1000xPY)
Although I'm looking at that and thinking I may be wrong and need to investigate your original formula
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-_
Al |
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iGRF
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Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6499 |
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Posted: 13 Mar 13 at 4:46pm |
Just get the Strava app for your iPhone.. er you do have an iPhone don't you? Don't worry your son will show you.. I bet he'd love the idea of getting that sled wound up across the water on a windy day.. Strava is an app the roadies use, I love using it on the sea next to where they ride, it really freaks them out. Especially when they can't come and get a KOM (King of the Mountain) it's like a rider challenge you could do it on your water set a course between two fixed buoys and challenge each other.. |
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Neptune
Really should get out more
Joined: 08 Jun 09 Location: Berkshire United Kingdom Online Status: Offline Posts: 1314 |
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Posted: 13 Mar 13 at 5:00pm |
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sounds dangerous, i reckon you could drive a slow underpowered boat way beyond any normalised breeze that would have the inshore lifeboats thinking again!
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Musto Skiff and Solo sailor
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SoggyBadger
Really should get out more
Joined: 26 Oct 10 Location: The Wild Wood Online Status: Offline Posts: 552 |
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Posted: 13 Mar 13 at 5:04pm |
Me too. His original formula has 3 opening parentheses and 4 closing parentheses so there's a (likely) typo there but correcting that gives CT = V * PY / 1000 |
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Best wishes from deep in the woods
SB |
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winging it
Really should get out more
Joined: 22 Mar 07 Online Status: Offline Posts: 3958 |
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Posted: 13 Mar 13 at 5:10pm |
Rupert, I got one of those new fangled puck thingies for my birthday. I could bring it to Whitefriars and we could data for all the cvrda boats! |
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the same, but different...
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