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woody 
Newbie 
Joined: 12 Dec 05 Location: United Kingdom Online Status: Offline Posts: 7 |
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 Topic: Mainsail Centre SheetingPosted: 18 Jan 06 at 10:58pm |
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Is centre sheeting on those classes that originally were designed with aft sheeting, a good and viable development for the class, or is it just a trend that has been developed from other classes that already have centre sheeting. By centre sheeting I mean that the mainsheet still runs to the end of the boom and then is roved back along the boom to a central position so their is little or no advantage that I can see. Please enlighten me.
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Black no sugar
Really should get out more 
Joined: 04 Dec 04 Location: Somewhere between Brighton and Lancing Online Status: Offline Posts: 3941 |
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Posted: 19 Jan 06 at 12:01am |
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Hi woody I don't know what class you're referring to, but there's been a lot of discussion here and on other fora about centre-main sheeting for Toppers. Here are the links to a couple of threads from other places http://www.gbrtopper.co.uk/forum/display_topic_threads.asp?F orumID=2&TopicID=172&PagePosition=2 http://dinghyforum.gamalan.net/topic.asp?TOPIC_ID=144
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Blobby
Really should get out more
Joined: 07 May 04 Location: Australia Online Status: Offline Posts: 779 |
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Posted: 19 Jan 06 at 5:27am |
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Personally I find centre sheeting infinitely more comfortable than aft sheeting and it is worth converting for that alone. It makes it much easier to tack and gybe facing forwards too.
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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: 19 Jan 06 at 5:40am |
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You've got to be amused at the way folk want to ignore the only hard data on the subject bacause it disagrees their preconceptions. Tells you a lot about human nature.
When I did the trial analysis I was surprised how it came out - I was expecting there to be no discernable difference. It makes me want to consider transom sheeting on my own boats, and if I were sailing a confined water roll tacking boat that would be the way I would go. Ask a National 12 sailor. Obviously for a fuller evaluation you need a lot more data, but it tells you a lot about how much hassle this sort of thing is to do that this is, I believe, the only trial of this kind that has ever been done. You would expect that the more tacking there is in proportion then the greater the superiority of aft main would be, but as we've already seen expectations can be quite wrong. However the most important thing to learn from this study is how tiny boat speed differences are compared to the differences between the performance of each sailor in individual races. Another lesson people don't want to learn! Edited by JimC |
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Blobby
Really should get out more
Joined: 07 May 04 Location: Australia Online Status: Offline Posts: 779 |
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Posted: 19 Jan 06 at 7:31am |
ConclusionEvaluation of the results obtained at the test event indicate that there may be a tiny performance difference between Toppers equipped with transom mainsheets and with the experimental centre mainsheet system, and that the centre mainsheet system was fractionally slower. The difference noted was approximately 20 seconds per hour, but there it seems possible that this was mainly due to the sailors being less familiar with the centre mainsheet system in use on a Topper. The difference noted was only marginally statistically significant and was tiny compared to the actual variation in finishing times in each race, which was about 2 minutes 40 seconds per hour This is your conclusion I believe - and certainly the comments on the other fora say Centre main is slower in light winds as you can't get the weight forward. Bear in mind though that this is talking about a centre-main system where the sheet is run off the boom down to a ratchet on the deck. Centre-main off the boom would seem to achieve the best of both worlds...more comfort and not in the way of moving forward. Certainly in my 29er I can tack "aft mainsheet style" when sitting on the mast bridge in the light and "centre-main style" in a breeze. But I agree completely that people ignore fact in favour of pre-conceptions. |
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Stefan Lloyd
Really should get out more
Joined: 03 Aug 04 Online Status: Offline Posts: 1599 |
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Posted: 19 Jan 06 at 8:23am |
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Jim, I've had a look at your report and your statistics. As you say, there is a 38% probability that the means of the centre and transom statistics are identical. Unfortunately, this is not a statistically significant result. It is common to look for significance at the 95% or 99% levels to demonstrate that two populations have different means. I'd also have a problem with the design of the experiment. It's not really very surprising that a group of sailors did better with the system they are familiar with, versus an experimental one. To demonstrate that one system was intrinsically faster than the other, you would need groups of sailors equally practiced with both. Finally, there is the question of causality. Why should one system be faster than the other?
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Simon Lovesey
Far too distracted from work 
Joined: 30 Nov 04 Location: United Kingdom Online Status: Offline Posts: 349 |
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Posted: 19 Jan 06 at 9:51am |
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The Mirror Class are investigating the introduction of an optional Centre Main and would welcome any feedback from other classes http://www.ukmirrorsailing.com/cgi-bin/forums/topic.asp?TOPI C_ID=4153
I fully agree with Jim's comments, we have spent the last two years testing new Bermuda rigs with the aim of modernising the Mirror, although not 100% scientific we have not seen any obvious performance differential, but people still get very hung up that there may be performance advantages of certain rigs, refusing to believe that the most performance differences come from the actual sailors. As many previous threads have discussed extensively one design classes need to evolve, this may or may not lead to performance gains, but the benefit of keeping a class popular will usually outweigh any downsides of change. Simon Edited by Simon Lovesey |
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m_liddell
Really should get out more
Joined: 27 May 05 Location: United Kingdom Online Status: Offline Posts: 583 |
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Posted: 19 Jan 06 at 10:59am |
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Centre mainsheet sheeting is now almost universal on all modern boats for a number of reasons: You can sheet in much faster by using your tiller hand and sheet hand to sheet in. this makes a massive difference at the leeward mark where boats like the enterprise were a pain. You can see where you are going while tacking and gybing! It is much easier to hike using the 'dagger grip' used on the tiller extension sailing centre main boats *note some of these points are valid only for non-twin wire boats. As a side note, I've found beginners find aft mainsheet easier to learn initially. Edited by m_liddell |
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Bogg Inne
Newbie
Joined: 19 Sep 05 Location: Burkina Faso Online Status: Offline Posts: 23 |
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Posted: 19 Jan 06 at 12:23pm |
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my kiddlys sailed Toppers through transition from aft to centre sheetin , there was a marked difference in their performance and ability to sail the boat in strong winds and overall they felt much happier in the setup ,imho a good move. Biggest difference was for my youngest and smallest @ <8 St became competitive too in stronger winds.
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If it ain't broke - break it
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woody
Newbie
Joined: 12 Dec 05 Location: United Kingdom Online Status: Offline Posts: 7 |
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Posted: 19 Jan 06 at 6:58pm |
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I can'nt see that it helps you to hike harder or enables you to sheet in quicker as on aft sheeting you can use your thumb to grip the sheet and grab much more sheet in one movement as opposed to lots of small grabs. While your sheeting in using this method it also makes it difficult to steer at the same time where on aft sheeting you can do both at the same time. As regards the possible development of the Mirror to accommodate centre sheeting, this is exactly what I'm on about. Is this really neccasary or just a trend that is driven by so called modern standards. Are we just sheep following the crowd?.
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, i.e. the Topper Discussion Forum and the Dinghy Sailing forum. They both come to roughly the same conclusion, but I leave you the pleasure to find out yourself! 
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