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Ssssslow boats in tide....... |
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 Topic: Ssssslow boats in tide.......Posted: 08 Nov 10 at 3:25pm |
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I personally would like to advocate locally adjusted PYs but the "personal handicap" arguement against is a strong one IMO. There are probably dozens of factors that can skew the PY at different locations but tidal effects seem to be one of the major issues, and, (possibly) one of the easier ones to deal with without resorting to personal handicap......again, your views on this would be gratefully received. I've done a few sums and compared 9yrs of average tidal results against non tidal (comparing PY groups) and the results suggest that the closer boat speed gets to tide speed the bigger the handicap they suffer.....The slow boats get clobbered, no suprises there. The sums I did were crudely suggestive I've taken a look at the HISC tide adjusted PY and am not sure that they've got it quite right...(The views of those who race at HISC would be appreciated) They've adjusted across the board but I reckon it just the slower boats that need a tweak. http://www.hisc.co.uk/2010_handicap_description.pdf Local tidal adjustment of PY is something I thought I would look into over the winter months, an ongoing project. Has anyone else tried to adjust for tide? or looked at it? or got an opinion? |
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Black no sugar
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Joined: 04 Dec 04 Location: Somewhere between Brighton and Lancing Online Status: Offline Posts: 3941 |
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Posted: 09 Nov 10 at 10:32am |
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In our club, we have our own "Lancing Correction Factor" that we use for about half of the series in the calendar.
Our results guru explained the logic behind it in this document: http://www.lancingsc.org.uk/downloads/lcf_full.pdf
To see the adjusted handicaps compared to PY in our club, have a look at http://www.lancingsc.org.uk/lcf_text.html
As a Topper sailor, I can say it works very well in light winds with reasonably flat water and tide. Add big waves to this and the Toppers don't stand a chance but that's due to a lack of pointy end rather than handicap adjustment!
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Rockhopper
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Joined: 16 Nov 07 Location: Eastry Online Status: Offline Posts: 642 |
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Posted: 09 Nov 10 at 12:20pm |
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at our club we sail in the afternoons on saturday and morning on the sundays so each day the tide is going in different direction which in turn levels out the adjustment needed some times we have up to three knots of tide which in you are say a topper is hard going but they still seem to do ok we dont have any really fast boats at our club the fastest one a rs 600 the rest seem to be vareos 2000s 200 and lasers and the odd topper.
So as for tide adjustment we dont bother but i think of next year we going to have personal handicap so mine in my vareo will i expect go down to 1015
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Retired now after 35 seasons in a row and time for a rest.
2004 national champ Laser5000 2007,2010,National Champ Rs Vareo |
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Posted: 09 Nov 10 at 12:36pm |
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Well I'll be.....Hadn't seen Mikes calcs before but I have exactly (well, nearly) the same graph on my spreadsheet....The closer a boat speed gets to tide speed the curve goes up exponentially. Thanks for the link BNS, I shall ponder.
One arguement at the club is "what they loose uptide, they get back downtide".....unfortunately that is not the case
 We have some very good Topper sailors, a shame their skills aren't reflected in the club results.
I've been trying to compare results of tidal handicap opens with non tidal, the results I have are very suggestive, unfortunately I don't think I have enough data to solve the issue though.....do you think the RYA would share theirs
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blueboy
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Joined: 27 Aug 10 Online Status: Offline Posts: 512 |
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Posted: 10 Nov 10 at 9:51am |
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I'm a HISC member: I sail in a handicap class some of the time and OD others (some events we get a class start, some we don't). I think it's a mistake to get too worked up about handicaps and handicap racing. The reality is that it's a rough science and it's either your conditions or it isn't, especially where handicap bands are wide. There will always be races that benefit fast boats or slow boats, especially in tidal waters. You see the same in yacht racing. That said, the HISC handicaps seem to work for us. We don't see particular classes as dominant or the opposite. We don't however have many very slow boats like Toppers doing general club racing. Chichester Harbour entrance isn't a very friendly place to sail such boats. Edited by blueboy - 10 Nov 10 at 10:08am |
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craiggo
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Joined: 01 Apr 04 Location: United Kingdom Online Status: Offline Posts: 1810 |
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Posted: 10 Nov 10 at 1:14pm |
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It depends entirely on the course. We have long distance races at our club that massively favour the slower boats, as generally they arrive at the furthest mark up river, as the tide turns and are therefore in a favourable current for the whole race. The fast boats get to the far end of the course before the tide turns and then spend half the leg back slogging against the last of the flood.
Around the cans the effect is less noticable although, downwind legs against the tide will always favour boats with kites. It must be remembered though that tactically positioning the boat in areas of weak tide makes a huge difference. At some point it is often worth ignoring the wind shifts and focus on the tide to get to the next mark quickest. As Blueboy says handicaps are a rough science, and it wont always be right, but if you run different courses throughout your season the advantages and disadvantages should even out. |
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Posted: 10 Nov 10 at 2:14pm |
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I think it's a mistake to get too worked up about handicaps
Agree but I like tinkering, also for me, it's about making the best of a bad situation.
The fast boats get to the far end of the course before the tide turns and then spend half the leg back slogging against the last of the flood.
I see your point but this sounds like a fairly unique race
 the advantages and disadvantages should even out.
That looks like the intuitive answer, unfortunately it's not the case. In the channel a boat spends about half the sailing season pushing and half being pushed. A slow boat looses a bigger percent of it's speed pushing and it has to do it for longer (compared to a fast boat), the speed is only partly regained when being pushed. Overall average for a season in tide a topper has between approx 8 and 10% extra penalty compared to a fast boat. Edited by GK.LaserII - 10 Nov 10 at 2:19pm |
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blueboy
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Joined: 27 Aug 10 Online Status: Offline Posts: 512 |
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Posted: 10 Nov 10 at 2:48pm |
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Well FWIW, the huge Round the Island Race for yachts also almost always favours slow boats because they start later, go slower and therefore carry favourable tide for longer, whereas fast boats slog against tide most of the way around. Also starting later, they usually get more breeze. Something like 8 times out of 10 the Gold Roman Bowl (IRC overall prize) goes to a boat in the slowest class. So maybe not an unique as all that for distance races to favour slower boats. |
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Posted: 10 Nov 10 at 3:40pm |
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Granted....There are probably a few big ones like your example. For coastal club dinghy handicap races it would be pretty unusual though, I say coastal club because I'm doing this to sort out a tidal local PY for us even though our club probably won't use it.
Even in club races there are loads of variables that alter the penalty for pushing/pushed so thats why I checked and compared some results from various locations, to see what was actually happening. That checking confirmed the penalty for slow boats in tidal waters.  Edited by GK.LaserII - 10 Nov 10 at 3:41pm |
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craiggo
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Joined: 01 Apr 04 Location: United Kingdom Online Status: Offline Posts: 1810 |
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Posted: 10 Nov 10 at 10:08pm |
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Having been responsible for the returns at our club for pretty much 10years, I've seen the impact of tide after all we do sail on the seconds most tidela stretch of water in the world!
We hold a series of long distance dinghy races where we see this effect. Its rare that fast boats win unless the wind direction is unusual or there are large fluctuations in wind strength. For normal round the cans racing we do see everything averaging out. It would be interesting to see what Portishead & Clevedon SC do. Interestingly Portishead Cruising Club who host the annual Holms race in the Bristol Channel apply a regression formula developed by a guy called Geoff McBroom as an additional correction on top of the standard handicap results to account for the fact that the slower boats are in more favourable tide for longer. This correction has been successfully applied in recent years resulting in a more varied outcome, wheras historically its was always a slow boat race. |
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