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Medway Maniac View Drop Down
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    Posted: 11 Mar 14 at 11:34am
Originally posted by JimC

Originally posted by Medway Maniac

A una (single sail) rig is more efficient than a sloop upwind (better lift/drag, although thrust/heeling moment is not so different)

Highly contestable statement I think

Which bit(s) do you find contestable, Jim?  At least one naval architect agrees with me http://www.sailingcatamarans.com/rigs.htm - see para 2 (not that aero engineers have much time for naval architects - far too many fudge factors in their maths!)

It's only a matter of time before NickA tells us of his V3k singlehanding, I guess...


Edited by Medway Maniac - 11 Mar 14 at 11:34am
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GarethT View Drop Down
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Posts: 714 		Post Options Post Options   Quote GarethT Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 11:40am
Didn't the Olympic singlehander have a jib (Firefly), but was too much like hard work so they downgraded to the physically less taxing Finn?
 
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Medway Maniac View Drop Down
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Posts: 2788 		Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 11:42am
Originally posted by Rupert

Jibs - yep, terrible things. Glad the AC boats put jibs on so the crew had something to do...

Yes, but they are pretty vestigial.  And A & C class cats used to have jibs, but no more.  The difference is that the A.C. things are allowed gennakers for when conditions permit.
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Posts: 403 		Post Options Post Options   Quote GybeFunny Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 11:48am
Originally posted by Rupert

Jibs - yep, terrible things. Glad the AC boats put jibs on so the crew had something to do...



Did you not see the race where one of the boats Jibs fell down and they cut it away and threw it overboard and still went on to win? In interviews they sailors admitted they had trialled the boats with no jibs and found it made little difference to straight line speed but was very useful in maneaouvres such as the bear-away.
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Rupert View Drop Down
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Posts: 8956 		Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 11:54am
I suppose having a jib or not isn't just to do with efficiency. It is to do with balance, breaking the sail area into useable segments, keeping the Cof E lower for a given sail area, adding sail in light winds in a way that is removable easily and quickly, even helping a boat come through the wind without getting into irons.

At the speeds that most dinghies go, though, I cannot see that the jib is going to make the boat slower compared to putting the area into the main, so for many singlehanders it will be ease of use which is the main factor in the decision.

The IC can be una rigged, I believe. The last time I paid attention, I don't think they had proved faster, but I may be out of date on that.

There is another high performance singlehander which has a jib. The Swift Solo in the USA.
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Medway Maniac View Drop Down
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Posts: 2788 		Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 12:11pm
Another factor is the adjustability of a una rig.  You can flatten and sheet it out when overpowered without concerns of backwinding and still needing to incorporate twist to accommodate the flow off the jib.  That message was driven home to me when a Contender simply flew up on us when we started dumping power in the Fireball on one occasion; fully powered up there had been little in it.

Fully powered-up upwind I suspect there is very little in it, as I said originally.
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Rupert View Drop Down
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Posts: 8956 		Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 12:30pm
The only bit I objected to really on the first post to bring the subject up was the idea that the jib was only there to give the crew some input. There are advantages to each arrangement, and I'm sure in a wind tunnel that unarig comes out ahead. Not so sure about the really strong winds - I guess it will depend upon both the boat and the situation, but there are times when being able to keep the jib driving while the main is flogging will be helpful.
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Medway Maniac View Drop Down
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Posts: 2788 		Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 12:33pm
Originally posted by Rupert

The only bit I objected to really on the first post to bring the subject up was the idea that the jib was only there to give the crew some input.

It's not a conclusion I came to happily!  But yes, there's more to the pleasure of sailing than just going quicker.

Edit:  I can think of a few singlehanded sailors who regard getting rid of the crew as a way of increasing their pleasure! (though I'm not in agreement there)

Just realised we're on the RS Aero thread!


Edited by Medway Maniac - 11 Mar 14 at 12:38pm
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Hector View Drop Down
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Posts: 750 		Post Options Post Options   Quote Hector Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 12:44pm
Originally posted by Medway Maniac

 

Just realised we're on the RS Aero thread!

About time somebody did.
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Posts: 284 		Post Options Post Options   Quote scotsfinn Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 2:46pm
One sail works ....Two sails are better than one though, especially with the dangly contraption on the Icon ....... and what is wrong with hi-jacking threads anyway Wink
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