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jeffers View Drop Down
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Posts: 3048 		Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Topic: Technical protest
    Posted: 19 Nov 19 at 10:02am
So the answer is that is isn't legal and should be removed then......
Paul
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gbrspratt View Drop Down
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Posts: 170 		Post Options Post Options   Quote gbrspratt Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 10:33am
Thanks for digging that up. That's a pretty clear answer on that one!! I'd be interested on your thoughts about fences on rudders and if you think they currently fit within the rules?
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Posts: 440 		Post Options Post Options   Quote ian.r.mcdonald Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 10:48am
With it easy to up spec a new Merlin over £30k, I would expect the concentration to be on racing.

But somehow I cant avoid being impressed by the continued drive to buy more bits!
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423zero View Drop Down
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 11:22am
General discussion on Merlin site
Robert
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 11:32am
Taken from latest rule book

C.8.2 Daggerboards, bilgeboards, double rudders, winged rudders and similar contrivances are prohibited
Robert
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fudheid View Drop Down
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Posts: 241 		Post Options Post Options   Quote fudheid Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 1:28pm
Originally posted by 423zero

Taken from latest rule book

C.8.2 Daggerboards, bilgeboards, double rudders, winged rudders and similar contrivances are prohibited

is a fence not a similar contrivance? there's no mention of fences in the ERS. so a fence is a contrivance? as it primarily used to affect leeway and/or produce vertical lift?


Edited by fudheid - 19 Nov 19 at 1:31pm
Cheers you

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JimC View Drop Down
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Posts: 6661 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 2:37pm
No, a fence has nothing to do with leeway or lift. Its purpose is to modify the boundary layer round the foil. The use on rudder blades is typically to attempt to reduce ventilation - sucking of air down from the surface - which causes the rudder foil to stall and the boat to lose control.
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Posts: 170 		Post Options Post Options   Quote gbrspratt Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 3:42pm
Originally posted by JimC

Originally posted by gbrspratt

   It originates from Merlin's and putting a halyard bag in between the kicker/boom/mast.


I see. Well that's easy enough and common enough. Attempted rule bending by logic chopping is nothing new: "if I can dream up a way to call extra [sail area|hull length|corrector weights|something else] a [something different] it must be legal".

Of course that's nonsense. If it quacks like a duck it counts as a duck. Just because its a halyard bag doesn't mean it isn't also sail area.



Is this not also true with a fence/wing/foil?

Definitely looks like a duck....
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fudheid View Drop Down
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Posts: 241 		Post Options Post Options   Quote fudheid Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 3:47pm
Originally posted by JimC

No, a fence has nothing to do with leeway or lift. Its purpose is to modify the boundary layer round the foil. The use on rudder blades is typically to attempt to reduce ventilation - sucking of air down from the surface - which causes the rudder foil to stall and the boat to lose control.

Ok so if it doesn't have anything to do with leeway or it isn't creating lift; what if the rudder is angled so the fence is at an angle to the flow of water does it creat lift then?
so it must be one of these as it is a contrivance of somesort? Fences are not  listed in the ERS so as a 'fence' it can be big as long as it is not producing lift (the national 12 rudder wing is not primarily about lift it is changing the flow of water off the stern - not lift?):
(d) FIN A fixed hull appendage primarily used to affect leeway or directional control. 
(k) TRIM TAB When a rudder(s) is used, a movable hull appendage, attached at the aft, or fore edge of another hull appendage.
(l) WING A hull appendage attached to a keel, bilge keel, canting keel, fin or bulb, primarily used to affect leeway and/or lift. (m) FOIL A hull appendage attached to a centreboard, daggerboard, bilgeboard or rudder, primarily used to affect leeway and/or produce vertical lift. 


Edited by fudheid - 19 Nov 19 at 3:53pm
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423zero View Drop Down
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 19 at 4:22pm
Fence is not a performance enhancer, it is a fit and forget item, purely for maintaining steerage, much the same as a release cleat on rudder or a centre board that knocks back, plus a myriad of other boat damage limiting useful inventions.

Edited by 423zero - 19 Nov 19 at 4:25pm
Robert
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