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Pointing-so whats that all about? |
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JimC
Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6649 |
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Topic: Pointing-so whats that all about? Posted: 22 Dec 17 at 9:07pm |
the Minisail doesn't have the best rig, foils or hull shape for pointing high.
Edited by JimC - 22 Dec 17 at 9:08pm |
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Rupert
Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
Post Options Quote Reply Posted: 22 Dec 17 at 9:30pm |
Get some speed up, get the chine in the water and you can get the boat pointing if you need to. Generally better to crack off a few degrees for speed, though. A decent sail set well helps a lot.
Mind, a lot of "pointing high" is actually spotting the lifts. |
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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423zero
Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3406 |
Post Options Quote Reply Posted: 22 Dec 17 at 9:36pm |
Will the Laser like battened sail fitted to my Sprint allow it to point higher than the simple Topper style triangular sail ?
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iGRF
Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6496 |
Post Options Quote Reply Posted: 22 Dec 17 at 10:10pm |
The Mini sail is under foiled, needs a bigger centre board. It goes sideways if you try to point too hard.
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Rupert
Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
Post Options Quote Reply Posted: 22 Dec 17 at 10:20pm |
That's where digging the chine in helps, but yes, they go better with a bigger board.
The sail won't make it point higher, but the greater power will mean you can pinch at times and maybe bleed the speed more slowly. Generally, keep the boat moving. Off the start line, ensure you have space to leeward. If you pinch when going slow, you will simply go sideways, and the low rig will be stuffed in dirty air. Make sure you can tack off and tack back into a clear lane, then build speed before you point higher. |
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Post Options Quote Reply Posted: 23 Dec 17 at 10:18am |
It's worth splitting leeway from pointing. Pointing angle is heading relative to true wind and leeway is the angle between heading and course. Bigger boards reduce leeway, but don't improve pointing angle.
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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: 23 Dec 17 at 10:41am |
I'm not convinced that's really a desirable split. What we call leeway is simply the angle of attack the board must operate at in order to create enough lift to balance the sails. If a board is very undersize or badly shaped it may have to operate at a significant angle of attack to create enough lift, and that's going to be especially true of any foil that doesn't maintain good flow on the windward side, but its more about lift than anything else. Once you have a board that's operating with decent attached flow both sides then extra area won't make much observable difference in a straight line at normal speed. Board size is really much more a differentiator when coming out of a tack when the board has to operate at very low speed with a lot of side load. |
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423zero
Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3406 |
Post Options Quote Reply Posted: 23 Dec 17 at 10:47am |
Regarding Centreboard size, is it length or breadth ? Or is it in relation to size of sail ?
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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: 23 Dec 17 at 11:06am |
All and none. The centreboard has to provide enough lift to balance the forces coming from the sail. Bigger sail, more force. A long thin centreboard can do that, so can a short fat one. The long thin one will do it with less drag, but will be less tolerant of being given too much work to do, at which point it will stall out. The short fat one has more drag, but will continue to create lift (with ever more horrendous drag) at angles where a long thin one will simply give up.so a compromise must be made, and the best compromise will be different for different boats. |
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423zero
Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3406 |
Post Options Quote Reply Posted: 23 Dec 17 at 11:57am |
This is centreboard fitted to Sprint (long and thin ?) approx 38" long by 14" wide at widest point. Appears looking at depth of hull and sail size to be adequate, not noticed much leeway, probably need someone following to have a proper look.
https://photos.google.com/photo/AF1QipNk9rVDCqP_NCaoebt0cBIcRnrYDO4GT6AUNsyT |
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