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So what's with mast rake? |
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ellistine
Really should get out more Joined: 06 Mar 08 Online Status: Offline Posts: 762 |
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Topic: So what's with mast rake? Posted: 24 Oct 10 at 9:19pm |
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It's one of those things that I've just accepted. The tuning guide says we should have a more upright mast in the light conditions and a more raked back mast when it's windy. I can see why an upright mast might help in the lighter conditions but what's the thinking behind raking the mast back when it's windy? What are we trying to achieve?
All I know is today our mast was raked back further than it's ever been (partly from stepping the mast in a hurry and not rechecking the pins) and with the wind in the upper teens we were stonking along. Properly planing up wind and even won the race both on the water and on corrected and that's never happened!
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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: 24 Oct 10 at 9:42pm | |
Well I think its probably the same reason as in windsurfing, which is that in increasing wind, the centre of effort of the sail moves aft so raking the rig back re-addresses the balance over the Centre of Lateral resistance, it also depowers the rig a tad.
With boats that can retract their centreboard, that is also a reason to rake the rig back.
Also in strong wind the sail isn't always sheeted in as far, so the entire rig isn't in play, raking it back keeps the c of e over c of lr balanced, probably more important on single handers. |
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JimC
Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6649 |
Post Options Quote Reply Posted: 24 Oct 10 at 11:17pm | |
To be quite honest the more I think about it the less I understand it... There are all sorts of things going on on a conventional dinghy from jib sheeting angle to the effect of the spreaders. I have a hunch that CLR is the least of it, but could easily be wrong.
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blueboy
Really should get out more Joined: 27 Aug 10 Online Status: Offline Posts: 512 |
Post Options Quote Reply Posted: 25 Oct 10 at 6:14am | |
Yep. I've never read a convincing explanation as to why raking a rig depowers it. All I know is that it works. |
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blueboy
Really should get out more Joined: 27 Aug 10 Online Status: Offline Posts: 512 |
Post Options Quote Reply Posted: 25 Oct 10 at 6:19am | |
The trouble with that theory is that keelboats also increase rake in stronger breeze. Also Merlins, for example, rake the rig long before they start raising the board.
That's 100% the wrong way around. If you ease the main-sheet, the luff depowers earlier than the leech. Therefore CoE moves back, so to restore balance you'd decrease rake, not increase it. |
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Fearfull
Newbie Joined: 20 Mar 09 Location: United Kingdom Online Status: Offline Posts: 11 |
Post Options Quote Reply Posted: 25 Oct 10 at 4:44pm | |
I have always thought there are two main reasons why I rake:
1. Center of effort of the sail moves forward as breeze increases, especially as the leech is doing less and less, so I rake to move this back to where it was. 2. As I rake the angle the shrouds are at makes the mast bend more. This is more noticable in rigs with raked spreaders. 3. Less tendancy to nose dive! Third is a bonus reason. |
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lynn1221
Newbie Joined: 26 Oct 10 Location: US Online Status: Offline Posts: 1 |
Post Options Quote Reply Posted: 26 Oct 10 at 10:34am | |
All I know is today our mast was raked back further than it's ever been
(partly from stepping the mast in a hurry and not rechecking the pins)
and with the wind in the upper teens we were stonking along. Properly
planing up wind and even won the race both on the water and on corrected
and that's never happened!
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tgruitt
Really should get out more Joined: 02 Dec 04 Online Status: Offline Posts: 2479 |
Post Options Quote Reply Posted: 26 Oct 10 at 11:08am | |
RAKE! |
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Needs to sail more...
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ifoxwell
Really should get out more Joined: 05 Jan 06 Location: Hoo Online Status: Offline Posts: 669 |
Post Options Quote Reply Posted: 26 Oct 10 at 11:24am | |
I tend to agree I've always thought that the most significant factor is that raking the rig lets it all breath better, jib slot opens up, spreaders let the mast bend more etc etc. The flaw in this theory however is that raking still works for a single sail, unstayed rig... so basically what i'm saying is that I don't have a clue either! Ian
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RS300
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blueboy
Really should get out more Joined: 27 Aug 10 Online Status: Offline Posts: 512 |
Post Options Quote Reply Posted: 26 Oct 10 at 12:52pm | |
But the leech doesn't do (relatively) less. The luff does less as you either feather (jib) or ease the mainsheet while vang-sheeting. 2. As I rake the angle the shrouds are at makes the mast bend more. This is more noticable in rigs with raked spreaders.[/QUOTE] But plenty of boats can adjust bend separately from rake e.g. with lowers, ram or backstay. Yet they all rake to depower as well as increasing mast bend. I don't have an alternative explanation to put forward and I know rake works. I just don't buy these explanations. |
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