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Upwind Problems |
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graeme_wilson
Newbie Joined: 19 Feb 13 Online Status: Offline Posts: 4 |
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Topic: Upwind Problems Posted: 20 Feb 13 at 1:56pm |
Did you get a reply to this ? would like to know myself
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Post Options Quote Reply Posted: 13 Sep 12 at 1:27pm |
How many times do old threads need reviving? Seems to be a specialty of yours DFF?
One way or another, I hope the OP's problem has been sorted by now! |
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G.R.F.
Really should get out more Joined: 10 Aug 08 Location: United Kingdom Online Status: Offline Posts: 4028 |
Post Options Quote Reply Posted: 13 Sep 12 at 1:17pm |
It's probably tide. Are the instruments GPS based?
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DFF
Newbie Joined: 22 Aug 12 Online Status: Offline Posts: 19 |
Post Options Quote Reply Posted: 13 Sep 12 at 11:49am |
All my money would be on the IRC break this boat sails in: you are against 33 ft - 40ft all and sundry most likely and they will :
1) go faster upwind due to pure water line legnth- tweaks to rig get you quarter of a knot , 8 feet on the water line give you a knot! 2) give you masses of wind shadow and disturbed flow as they sail ahead of you due to 1: try sailing out to the right hand side of the course asap, even start behind the transom of a bigger boat at the committee boat end and tack away as soon as you can to the RHS.
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Crewing on a Melges 24, against my better judgement...
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NickM
Far too distracted from work Joined: 27 May 09 Location: United Kingdom Online Status: Offline Posts: 328 |
Post Options Quote Reply Posted: 03 Feb 12 at 6:51pm |
I once sailed in a Sonata that had a slightly sideways bent mast and it behaved exactly as you desibe: much faster and higher on the tack towards which the mast was bent. Have you looked up your track to check it is straight?
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bert
Really should get out more Joined: 23 Apr 05 Location: norwich usually Online Status: Offline Posts: 584 |
Post Options Quote Reply Posted: 03 Feb 12 at 2:43pm |
"all my money" would be on the question being answered ----- last year
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Phantom 1181
AC-227 IC 304 blaze / halo 586 |
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nathan
Posting king Joined: 26 Apr 04 Online Status: Offline Posts: 143 |
Post Options Quote Reply Posted: 03 Feb 12 at 1:40pm |
All my money would be on dodgy instruments... |
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Isis
Really should get out more Joined: 01 Sep 05 Online Status: Offline Posts: 2753 |
Post Options Quote Reply Posted: 03 Feb 12 at 11:48am |
Im willing to bet your observed change in speed and TWA is an instrumentation setup or calibration issue. Remember that even when everything is central you have things like wind sheer which affect readings from tack to tack. On high end instrumentation its possible to dial all this out so that your numbers are identical, but many people prefer to leave it as it and calculate the shear offset in their heads as you go.
If you are sure its a boat speed issue then making sure the rig is central and in line with the keel is the first priority. If you cant get the boat out the water then measuring from the mast tip to the toe rail on each side as suggested above is a reasonable approach but never assume anything is truly symetrical. Its more important to have the mast in line with the keel than to have it perpendicular to the deck. There are any number of other things it might be related too but the rig being out is the most common and easiest to sort out so its worth starting there. |
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rb_stretch
Really should get out more Joined: 23 Aug 10 Online Status: Offline Posts: 742 |
Post Options Quote Reply Posted: 01 Nov 10 at 5:06pm |
Have to say I've never had a keel boat where both tacks were identical, despite checking everything was central. It is very difficult to calibrate the wind to be spot on, often waves are not always directly in line with the wind and then you have tidal effects......almost impossible to account for it all. |
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nmartin
Newbie Joined: 01 Nov 10 Online Status: Offline Posts: 2 |
Post Options Quote Reply Posted: 01 Nov 10 at 1:09pm |
Thanks for the advice - I'll double check the cars and measure how central the rig is.
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