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Topic: Technical protest Posted: 20 Nov 19 at 12:10am |
C.8.2 Daggerboards, bilgeboards, double rudders, winged rudders and similar contrivances are prohibited
I would have said a fence was a “similar contrivance” in as much as it is an atypical modification to conventional rudder design. That said, it seems a pity to ban it and I would be interested to know if it actually improves things or whether the increased wetted area and interference drag are more of a hindrance. |
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fudheid
Far too distracted from work Joined: 21 Apr 11 Location: 51.53 N 01.28 E Online Status: Offline Posts: 241 |
Post Options Quote Reply Posted: 20 Nov 19 at 8:32am |
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Edited by fudheid - 20 Nov 19 at 8:35am |
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Cheers you
only me from over the sea...... |
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fudheid
Far too distracted from work Joined: 21 Apr 11 Location: 51.53 N 01.28 E Online Status: Offline Posts: 241 |
Post Options Quote Reply Posted: 20 Nov 19 at 8:34am |
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Cheers you
only me from over the sea...... |
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Granite
Far too distracted from work Joined: 12 May 04 Location: Scotland Online Status: Offline Posts: 476 |
Post Options Quote Reply Posted: 20 Nov 19 at 12:50pm |
Most fences I have seen on rudders have been flat plates paralell to the flow to stop ventelation down the rudder, so only have a positive effect at very high rudder angles, or possibly very high speed. Looking at the pictures of the rudder I am not sure where the fence sits against the waterline. It looks like it could sit just above the water and be used to deflect the water cleanly away from the rudder/stock. Avoiding disrupted flow across the stock and some potential drag. Although it also looks like the bit of blade above the fence has a sharper leading edge which I think is wanted at the surface to cut the water cleanly putting the fence below the water. Whatever it does the height of the blade is going to be critical in its performance. I think it would need some very complex CFD to be sure that it is having the desired effect and not adding drag. For the rules I suspect they forgot about fences which had probably been seen before on a lot of boats. Although this rule is interesting: E.2.1 RULES The hull appendages shall comply with these class rules or the class rules in force at the time of initial hull certification. It could potentially mean you could fit full sized wings on to the rudder of an older boat |
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If it doesn't break it's too heavy; if it does it wasn't built right
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