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scotsfinn View Drop Down
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Posts: 284 		Post Options Post Options   Quote scotsfinn Quote  Post ReplyReply Direct Link To This Post Topic: R Speculation
    Posted: 11 Mar 14 at 2:51pm
Icon single hander
Originally posted by scotsfinn

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
Largs Sailing Club. D-Zero GBR 57, B14 744
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blaze720 View Drop Down
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Posts: 1635 		Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 6:03pm
Come on Martin ... lets move across to the Icon thread then ... and when there pray tell us what  is the local handicap for single crew + single sail ?  If the balance is reasonable I might try it myself - sail area is almost exactly 10m and beam is just about 1.94m 

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Chris 249 View Drop Down
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Posts: 2041 		Post Options Post Options   Quote Chris 249 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 14 at 7:12pm
Originally posted by Medway Maniac

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...

What works on cats often doesn't work on monos. For example, there have been numerous attempts to get a big wingmast working on monos but very few of them have made the grade, and then only in a couple of classes that appear to be in a similar performance range.

Aeronautical legend Mark Drela has pointed out that what counts in sailing rigs is the lift/drag ratio of the entire unit, not just the rig. The hull on a mono has very high drag, therefore a rig with very high lift is what is needed - reducing rig drag is of much less relevance as it's such a small component of the overall drag.

In comparatively low drag hulls as seen in multis, rig drag becomes much more important and apparent wind also comes into it. This was really brought home to me by playing around with different windsurfer rigs and boards - the high drag/high lift longboard rigs don't work on a slalom board and vice versa. 

It all means that a rig that works on a cat or a Moth does not work on a skiff or normal hiking singlehander.  Cat rigs have been tried on ICs and many other mono classes, without success. In my very slight personal experience the handling difficulties are significant. 
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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 8:12pm
Agreed, the optimum rig will depend upon the boat-speed relative to the windspeed insofar as this determines the average apparent wind angle.  But I think the statements I made still hold true for slower boats.
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NickA View Drop Down
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Posts: 784 		Post Options Post Options   Quote NickA Quote  Post ReplyReply Direct Link To This Post Posted: 14 Mar 14 at 2:15pm
"It's only a matter of time before NickA tells us of his V3k singlehanding, I guess..."

if you insist  Smile

The 3000 is total cr$p with only the main sail up; overtaking solos is hard work.  Mostly because the balance is wrong and it's always fighting to head up wind (as does an RS700, in my limited and novice experience!).

Pointing ability aside, a sloop rig gets more power lower down the mast, so more drive per heeling force.  Also the interaction of jib and main is supposed to improve the performance of the main by accelerating wind across it.  On the Javelin (FD, 5o5 etc), which have huge genoas, the slot effect makes a huge difference as if you get it wrong the boat is a dog and if you get it right you're planing up wind.  According to Bethwaite this is why uncleating the jib makes such an unexpectedly large difference to the boat forces ..... not that I've noticed that on the V3k where I often un-cleat the jib from out on the wire before a tack without falling in backwards.  So two sails might be more efficient from a power point of view - but the jib might have to be an unwieldy size to make enough difference.

The other biggy is that on a unarig you only have to play one sail through gusts, which unless you have a crew (and a very good one), doesn't happen effectively with two sails .... except on a Swift Solo.

Also  -  if the manufacture can sell you a boat for £5000 odd quid but only has to provide one sail, fewer cleats and blocks and certainly no self tacking track, they make more money!


PS:  "As to the chine shape, Nick, the leaflet says: "the chine has a small lip (or land) in order to reduce spray drag and for precise positioning of the computer cut PU foam panels during construction"

I was standing under a 49er at the National Maritime Museum yesterday and noticed that it also has (quite pronounced) "lands".  Though in other fast boats, neither the i14, MPS, RS800 nor 18ft skiff have them ...still a bit of a mystery to me .... but I am a 'trician not a hydrodynamicist.


Edited by NickA - 14 Mar 14 at 2:44pm
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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: 14 Mar 14 at 3:11pm
That's all very subjective and speculative, Nick.  But until we get a class that allows the choice of any rig you like with no holds barred, and just limits righting moment*, we will never get proof one way or the other.

With an aft- raked Tasar daggerboard, the V3k is actually well-balanced when sailed on mainsail alone, but is, as you say, dog slow without the kite up.  Try sticking a bigger, e.g. Contender, rig on, maybe? 

[*as I've pointed out, even classes like the IC which allow a fair bit of freedom still limit mast height and total sail area]
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 14 at 6:19am
Aero video

How do you embed?
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Ruscoe View Drop Down
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Posts: 1514 		Post Options Post Options   Quote Ruscoe Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 14 at 7:09am
Got showed that vid last night, couple of points.

1) the sticker is coming off the foils.
2) it's just the boat reaching everywhere, with about 3 seconds of upwind.  
3) at 59 seconds ish, when the video is slowed to show the bow lifting off a wave, I notice they cut to another seen as it looks like the bow is going to burry into the back of another wave.

I guess in fairness they are not going to develop a promo video of the worse bits are they, I can understand keeping the bow out the back of the wave.  But for the love of god, show the boat going up wind.....


Whilst I know it's a promo to sell more boats, any boat looks good on a broad reach in a nice blow.  Especially when the helm exaggerates their pumping action.

Over produced and edited. Shame, just my opinion.


Edited by Ruscoe - 21 Mar 14 at 7:15am

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Alistair426 View Drop Down
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Posts: 201 		Post Options Post Options   Quote Alistair426 Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 14 at 8:21am
Originally posted by Ruscoe

  But for the love of god, show the boat going up wind.....

...in light of the comments (following Northants Demo Day and quoted hereon) that the boat, being so light and carrying little momentum, loses speed rapidly when headed/feathered, it might struggle a bit in the Hayling Chop and not make pleasant viewing.  Wink

The Aero is never going to be fast enough to plane upwind so one of its USPs (super-lightness) might be a drawback. You'll have a stream of punters queuing up and saying 'if you add 20Kg, I'll have one'!  LOL

Or I might be wrong.  Embarrassed
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L123456 View Drop Down
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Posts: 500 		Post Options Post Options   Quote L123456 Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 14 at 8:27am
What boat does not look ok downwind in a bit of breeze ... Would be good to see some upwind. 

Boom looks too angled up to me. 
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