Posted: Wed May 11, 2005 3:01 am
Moe, et. Al
Ya kind a put a lot of points in your paragraphs and diagrams.. but since I am back from a nice windy trip to Neah Bay.I guess I have it all fresh in my mind,.. and a tired butt and wet boat for some reason.lol someone really needs to come up with an exercise regimen for cockpit bound sailors.
I have seen many things in the last couple of weeks.and even the murrelet with the turquoise back feathers.. heheheheh;) when I went in to Seattle to get some more goodies, (Even FM knows where to get good service in Seattle) (and no I dont work for them or receive any kickback for stating the truth.. BWY Is a great outfit to deal with..Between Bill at B4sale and BWY.. I am reasonably comfortable breaking anything on my boat. ) and I need a heavy storm jib.
Like many here On my X I use a Vang and a Boomkicker, for leach tension.and boom support., the M boats I have looked at are interesting in their methods of attaching the kicker and the vang tail to the base of the rotating mast.to keep them free.
To improve pointing and handling, I do mainsheet though railing clips.and it does funky things to the boom and sail footwhen pulled hard and upwind... (on the front railing this ends up pulling the boom into a small bow..and deepening the fill of the sail) which aerodynamically will result in more lift, and a little more drag..for that extra half a point one pics up on ground track.
Angle of attack is the critical element here.and a point where the Ms (even with their short traveler) have an advantage. Two reasons I really like sheeting to the windward rail are 1) improvement of the angle of attack and, 2) in upset conditionsI have another 15 to 20 degrees of boom travel available to ease off the wind (Ok, OK, those of you who know me know I end up dumping sheets way too oftenlol) while still maintaining some semblance of control on the boat. (but I have a much more controllable boom7 unloaded 1 to 2 points before it swings out of range)
One of the things that I have trouble with my sailboats is that I keep thinking of the mast/sail combination as a fixed wing configurationwrong analogy. ( I learned to fly after I learned to fall, but in flying they teach only the FAA way..) Sailboats dont fly like planes, they fall like kitesconverting altitude/wind to forward distance traveled., sailboat main foils are designed that as soon as you are heeling you are warping the wing(by adding some of the twist Moe refers to).. ( and moving the stall line) also because the captured air in the sail does not want to stay in the pocket and will move to the closest lower pressure area..in a sailboats case, that is normally slightly rising along the leech..as our telltales show us. The upper sail is twisting into the wind (losing lift and stalls first) If someone really wants to compare to an airplane flying.. the closest approximation is in a turning descent with no power on.
There have been many designs of rigid ribbed and composite rigid sails which have even AOA throughout their height but with heeling, spill velocities , and weight aloft, the gains from these structures generally are not worth the corresponding increase in hull strengths and weights (all of which ends up above CB and CG)
Getting back to Moes major comment if the tightness of the leech allows the top to luff first then the sail is not presented evenly to the apparent wind on the sail. Sheeting to luff the leech evenly will obtain more lift out of the top of the sail, and allows more power to be obtained out of the wind in a close beat..
For a reach I still occasionally use the rails (instead of just the pedestal ring), but like most everyone.. I sail to the aft telltales (the belly of the sail) so as to stay on reach.
And the more windward the boom is sheetedthe less downward force on the boom, and the deeper the sail. I cant find it in Chapmans/ royces.at the moment.but there is something that says the greatest thrust on the sail is a result from the greatest differential pressure between the two sides of the sailand this occurs at sail conditions with the greatest sail depth over the largest area, for a given sheet tension.
Moral of the story
When beating, If you can sheet more to windward, you can maintain better control, reduce heel, fill the sail more, and effect a greater change when releasing sheets.without causing the boat to round up so far in a recovery.
JMHO
|>arren
Ya kind a put a lot of points in your paragraphs and diagrams.. but since I am back from a nice windy trip to Neah Bay.I guess I have it all fresh in my mind,.. and a tired butt and wet boat for some reason.lol someone really needs to come up with an exercise regimen for cockpit bound sailors.
I have seen many things in the last couple of weeks.and even the murrelet with the turquoise back feathers.. heheheheh;) when I went in to Seattle to get some more goodies, (Even FM knows where to get good service in Seattle) (and no I dont work for them or receive any kickback for stating the truth.. BWY Is a great outfit to deal with..Between Bill at B4sale and BWY.. I am reasonably comfortable breaking anything on my boat. ) and I need a heavy storm jib.
Like many here On my X I use a Vang and a Boomkicker, for leach tension.and boom support., the M boats I have looked at are interesting in their methods of attaching the kicker and the vang tail to the base of the rotating mast.to keep them free.
To improve pointing and handling, I do mainsheet though railing clips.and it does funky things to the boom and sail footwhen pulled hard and upwind... (on the front railing this ends up pulling the boom into a small bow..and deepening the fill of the sail) which aerodynamically will result in more lift, and a little more drag..for that extra half a point one pics up on ground track.
Angle of attack is the critical element here.and a point where the Ms (even with their short traveler) have an advantage. Two reasons I really like sheeting to the windward rail are 1) improvement of the angle of attack and, 2) in upset conditionsI have another 15 to 20 degrees of boom travel available to ease off the wind (Ok, OK, those of you who know me know I end up dumping sheets way too oftenlol) while still maintaining some semblance of control on the boat. (but I have a much more controllable boom7 unloaded 1 to 2 points before it swings out of range)
One of the things that I have trouble with my sailboats is that I keep thinking of the mast/sail combination as a fixed wing configurationwrong analogy. ( I learned to fly after I learned to fall, but in flying they teach only the FAA way..) Sailboats dont fly like planes, they fall like kitesconverting altitude/wind to forward distance traveled., sailboat main foils are designed that as soon as you are heeling you are warping the wing(by adding some of the twist Moe refers to).. ( and moving the stall line) also because the captured air in the sail does not want to stay in the pocket and will move to the closest lower pressure area..in a sailboats case, that is normally slightly rising along the leech..as our telltales show us. The upper sail is twisting into the wind (losing lift and stalls first) If someone really wants to compare to an airplane flying.. the closest approximation is in a turning descent with no power on.
There have been many designs of rigid ribbed and composite rigid sails which have even AOA throughout their height but with heeling, spill velocities , and weight aloft, the gains from these structures generally are not worth the corresponding increase in hull strengths and weights (all of which ends up above CB and CG)
Getting back to Moes major comment if the tightness of the leech allows the top to luff first then the sail is not presented evenly to the apparent wind on the sail. Sheeting to luff the leech evenly will obtain more lift out of the top of the sail, and allows more power to be obtained out of the wind in a close beat..
For a reach I still occasionally use the rails (instead of just the pedestal ring), but like most everyone.. I sail to the aft telltales (the belly of the sail) so as to stay on reach.
And the more windward the boom is sheetedthe less downward force on the boom, and the deeper the sail. I cant find it in Chapmans/ royces.at the moment.but there is something that says the greatest thrust on the sail is a result from the greatest differential pressure between the two sides of the sailand this occurs at sail conditions with the greatest sail depth over the largest area, for a given sheet tension.
Moral of the story
When beating, If you can sheet more to windward, you can maintain better control, reduce heel, fill the sail more, and effect a greater change when releasing sheets.without causing the boat to round up so far in a recovery.
JMHO
|>arren