sailorman
Well-Known Member
Re: Leeway: Here\'s the only answer
Jimi he might be usin the Ole iron Torpsl /forums/images/graemlins/ooo.gif
Jimi he might be usin the Ole iron Torpsl /forums/images/graemlins/ooo.gif
Leeway
- Thread starter jrt
- Start date
markleuty
Well-Known Member
Re: Consider the keel as a sail as well ...
Hey! Freestyle, I've got one of those as well.
Always a major talking point whenever she's out of the water..
Mark
Hey! Freestyle, I've got one of those as well.
Always a major talking point whenever she's out of the water..
Mark
oldsalt
Well-Known Member
Re: Leeway: Here\'s the only answer
Nothing to do directly with the waves in theory. In waves, the boat is going slower, and may even stall, thus the keel is less efficient so there is more leeway. The leeway is not directly caused by the waves, it is caused by the boat going slower and a less efficient keel. A good helmsman will negate this effect as much as possible.
Anyway, I think we are spliting hairs, even ba' hairs...
Nothing to do directly with the waves in theory. In waves, the boat is going slower, and may even stall, thus the keel is less efficient so there is more leeway. The leeway is not directly caused by the waves, it is caused by the boat going slower and a less efficient keel. A good helmsman will negate this effect as much as possible.
Anyway, I think we are spliting hairs, even ba' hairs...
matelot
Well-Known Member
Re: Leeway: Here\'s the only answer
there's an awful lot of high horses around this afternoon. hang loose - if thats a safe thing to say given the demographic on this forum.
peace and goodwill to all the miserable old curmudgeons out there
there's an awful lot of high horses around this afternoon. hang loose - if thats a safe thing to say given the demographic on this forum.
peace and goodwill to all the miserable old curmudgeons out there
john_morris_uk
Well-Known Member
Re: Leeway: Here\'s the only answer
[ QUOTE ]
You, too, have misunderstood my post. I am not asking LadyInBed for clarification of the meaning of leeway, but for clarification of what he, or she, thinks is leeway. There is a rather large difference.
To save anyone else the trouble of patiently explaining this term to me:
I know what leeway is
I know how to apply it in navigation and pilotage
I know it still applies in the example I have given
I have known these things for around 45 years
I have taught a goodly number of people to apply these calculations in their chartwork
I apply them in my own chartwork
I am interested in the interpretation put forward by LadyInBed, which is acknowledged to be incorrect. Does LadyInBed still think of it as leeway, even when the accumulation of forces he or she mentions move the boat in a windward direction in relation to the course to steer, which is to say that the effects of leeway, which are, of course, still present, are weaker than the effects of tidal set.
Does that clarify matters? /forums/images/graemlins/smile.gif
[/ QUOTE ]My apologies if I misunderstood your post. In mitigation I wasn't the only one to think you were asking a question for yourself.
[ QUOTE ]
You, too, have misunderstood my post. I am not asking LadyInBed for clarification of the meaning of leeway, but for clarification of what he, or she, thinks is leeway. There is a rather large difference.
To save anyone else the trouble of patiently explaining this term to me:
I know what leeway is
I know how to apply it in navigation and pilotage
I know it still applies in the example I have given
I have known these things for around 45 years
I have taught a goodly number of people to apply these calculations in their chartwork
I apply them in my own chartwork
I am interested in the interpretation put forward by LadyInBed, which is acknowledged to be incorrect. Does LadyInBed still think of it as leeway, even when the accumulation of forces he or she mentions move the boat in a windward direction in relation to the course to steer, which is to say that the effects of leeway, which are, of course, still present, are weaker than the effects of tidal set.
Does that clarify matters? /forums/images/graemlins/smile.gif
[/ QUOTE ]My apologies if I misunderstood your post. In mitigation I wasn't the only one to think you were asking a question for yourself.
sailorman
Well-Known Member
Re: Leeway: Here\'s the only answer
Jonnie did you used to have a sideline sellin hot chestnuts a few yrs ago /forums/images/graemlins/grin.gif
Jonnie did you used to have a sideline sellin hot chestnuts a few yrs ago /forums/images/graemlins/grin.gif
grumpy_o_g
Well-Known Member
Re: ... and that\'s not true either
Taking the analogy of leading slats on an aircraft (which may not be valid as the distance is a lot less) the air flow is sped up by a Venturi effect as the higher pressure air under the slat is forced through the narrow gap between the slat (foresail) and wing (mainsail). I'd always assumed that the effect was similar from the windward side of a fore-sail.
Regardless of the speed of the airflow, the fact that the foresail trim can be critical with regard to the mainsail can be seen from the ability to backwind the main comparatively easily, even without an over-lapping Genoa. Less now it seems, but it was common practice to de-power the main by over sheeting the Genoa. I used to do it on Enterprises sometimes.
I'd have thought the the slot effect of tandem keels would be less as water is so much denser. The water would deflect less and return to a parallel laminar flow but that's a real guess.
Taking the analogy of leading slats on an aircraft (which may not be valid as the distance is a lot less) the air flow is sped up by a Venturi effect as the higher pressure air under the slat is forced through the narrow gap between the slat (foresail) and wing (mainsail). I'd always assumed that the effect was similar from the windward side of a fore-sail.
Regardless of the speed of the airflow, the fact that the foresail trim can be critical with regard to the mainsail can be seen from the ability to backwind the main comparatively easily, even without an over-lapping Genoa. Less now it seems, but it was common practice to de-power the main by over sheeting the Genoa. I used to do it on Enterprises sometimes.
I'd have thought the the slot effect of tandem keels would be less as water is so much denser. The water would deflect less and return to a parallel laminar flow but that's a real guess.
Litotes
Well-Known Member
Re: Leeway: Here\'s the only answer
[ QUOTE ]
[
[/ QUOTE ]My apologies if I misunderstood your post. In mitigation I wasn't the only one to think you were asking a question for yourself.
[/ QUOTE ]
No problem, but I did rather think I had made myself reasonably clear in my first answer to Jazz (who commented - we still don't understand it...? or words to that effect.....)
My answer:
"Oh, but I think we do. I'm just interested in the boundaries of LadyInBed's definition, which is acknowledged to be incorrect. "
[ QUOTE ]
[
[/ QUOTE ]My apologies if I misunderstood your post. In mitigation I wasn't the only one to think you were asking a question for yourself.
[/ QUOTE ]
No problem, but I did rather think I had made myself reasonably clear in my first answer to Jazz (who commented - we still don't understand it...? or words to that effect.....)
My answer:
"Oh, but I think we do. I'm just interested in the boundaries of LadyInBed's definition, which is acknowledged to be incorrect. "
Kurrawong_Kid
Well-Known Member
Re: Ouch Ouch Ouch ....
Aha! Those who work sail at weekends, those retired try to fit shorepower midweek! Ask Steve if we've been seen!
Aha! Those who work sail at weekends, those retired try to fit shorepower midweek! Ask Steve if we've been seen!
sailorman
Well-Known Member
Re: Ouch Ouch Ouch ....
You will need a meter then /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
You will need a meter then /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
DownWest
Well-Known Member
Re: ... and that\'s not true either
Yes and no, slats are more about keeping the airflow on the surface of the foil at low speeds. The problem of wings is that one needs one profile for takeoff and landing and another,much slimmer, one for cruising at high speed. The slats lower the stall speed (along with the flaps). Boats use some of this to increase the angle of attack of the combo of fore/main. As in sail closer to the wind. Of course, pinching too tight causes more leeway.............
A
PS Jim B is much better at explaining this than I.
Yes and no, slats are more about keeping the airflow on the surface of the foil at low speeds. The problem of wings is that one needs one profile for takeoff and landing and another,much slimmer, one for cruising at high speed. The slats lower the stall speed (along with the flaps). Boats use some of this to increase the angle of attack of the combo of fore/main. As in sail closer to the wind. Of course, pinching too tight causes more leeway.............
A
PS Jim B is much better at explaining this than I.
Salty John
Well-Known Member
I can see how a simple question like that would make you sit up and think!
As I'm sure you've realised since posing the question on here, leeway is the difference between the course steered over the water and the course achieved over the water.
I suppose the person who asked the question in your class was thinking in terms of how leeway might be minimised by steering - if the boat is simply being made to turn away from the desired course, why not just compensate? Of course leeway can include helmsman's error - one helmsman might be better at sailing close to the wind than another, for instance, but the resultant divergence from the desired course is still leeway!
In the end, leeway is simply the difference between the desired course over the water and the achieved course over the water. Nothing more, nothing less.
Tidal set, which I'm sure you also realise, will cause your steered course to differ from your course achieved over the ground.
As I'm sure you've realised since posing the question on here, leeway is the difference between the course steered over the water and the course achieved over the water.
I suppose the person who asked the question in your class was thinking in terms of how leeway might be minimised by steering - if the boat is simply being made to turn away from the desired course, why not just compensate? Of course leeway can include helmsman's error - one helmsman might be better at sailing close to the wind than another, for instance, but the resultant divergence from the desired course is still leeway!
In the end, leeway is simply the difference between the desired course over the water and the achieved course over the water. Nothing more, nothing less.
Tidal set, which I'm sure you also realise, will cause your steered course to differ from your course achieved over the ground.
grumpy_o_g
Well-Known Member
Re: ... and that\'s not true either
Yes, agreed and I understand what you're getting at but remember they keep the airflow on the surface by accelerating the airflow over the upper surface. This keeps the transition point further aft. Some aircraft simply use bleed-air from the engines to provide an accelerated airflow over the upper surface for low speed.
Technically something that changes the shape of the aerofoil at the leading edge without introducing a slot between it and the main-plane is a leading-edge flap, not a slat.
If you simply change to a fuller shape you're more likely to actually cause the airflow to break away at very low speeds - one of the reasons you keep the sail flatter in very light winds. Aircraft obviously don't have the luxury of that option as they have to keep the amount of lift produced by the wing more or less equivalent to the weight of the aircraft.
Yes, agreed and I understand what you're getting at but remember they keep the airflow on the surface by accelerating the airflow over the upper surface. This keeps the transition point further aft. Some aircraft simply use bleed-air from the engines to provide an accelerated airflow over the upper surface for low speed.
Technically something that changes the shape of the aerofoil at the leading edge without introducing a slot between it and the main-plane is a leading-edge flap, not a slat.
If you simply change to a fuller shape you're more likely to actually cause the airflow to break away at very low speeds - one of the reasons you keep the sail flatter in very light winds. Aircraft obviously don't have the luxury of that option as they have to keep the amount of lift produced by the wing more or less equivalent to the weight of the aircraft.
john_morris_uk
Well-Known Member
Re: Leeway: Here\'s the only answer
[ QUOTE ]
Jonnie did you used to have a sideline sellin hot chestnuts a few yrs ago /forums/images/graemlins/grin.gif
[/ QUOTE ]Huh? Lost me completely on this one. Must be my age?
[ QUOTE ]
Jonnie did you used to have a sideline sellin hot chestnuts a few yrs ago /forums/images/graemlins/grin.gif
[/ QUOTE ]Huh? Lost me completely on this one. Must be my age?
sailorman
Well-Known Member
Re: Leeway: Here\'s the only answer
you obviously still wear short trousers /forums/images/graemlins/blush.gif
you obviously still wear short trousers /forums/images/graemlins/blush.gif
DownWest
Well-Known Member
Re: ... and that\'s not true either
Hum, the slats I was thinking of were on a DH 82a, but the ones I see on Ryanair´s best are still similar? I remember one type of a/c that had rotating cylinders between the wing and the flaps to help the airflow stay attached. Bit too much thread leeway perhaps.
A
Just a thought, the further one pushes the envelope, the quicker the fall. Not a prob on a boat, bit tricky on a plane.
Hum, the slats I was thinking of were on a DH 82a, but the ones I see on Ryanair´s best are still similar? I remember one type of a/c that had rotating cylinders between the wing and the flaps to help the airflow stay attached. Bit too much thread leeway perhaps.
A
Just a thought, the further one pushes the envelope, the quicker the fall. Not a prob on a boat, bit tricky on a plane.
colvic987
Well-Known Member
JRT,
With all the flak you've had off this lot, you definitely needs lots of leeway. /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif
With all the flak you've had off this lot, you definitely needs lots of leeway. /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif
john_morris_uk
Well-Known Member
Re: Leeway: Here\'s the only answer
[ QUOTE ]
you obviously still wear short trousers /forums/images/graemlins/blush.gif
[/ QUOTE ]Only in the summer and I just discovered that I am the oldest person on board my ship. Can you explain your comments as I have no idea what you are referring/alluding to.
[ QUOTE ]
you obviously still wear short trousers /forums/images/graemlins/blush.gif
[/ QUOTE ]Only in the summer and I just discovered that I am the oldest person on board my ship. Can you explain your comments as I have no idea what you are referring/alluding to.
sailorman
Well-Known Member
Re: Leeway: Here\'s the only answer
many many yrs ago Johnny Morris ( TV personality ) used to sit by a brazier heating chestnuts telling stories on TV during children's hr.
well thats Wot my GrandPa said /forums/images/graemlins/blush.gif
many many yrs ago Johnny Morris ( TV personality ) used to sit by a brazier heating chestnuts telling stories on TV during children's hr.
well thats Wot my GrandPa said /forums/images/graemlins/blush.gif
stephenh
Well-Known Member
Re: Leeway: Here\'s the only answer
"A farm manager in Wiltshire for thirteen years,[2] Morris was discovered telling stories in a pub by the then BBC Home Service West Regional producer Desmond Hawkins. Morris made his radio debut in 1946, and featured in a number of Regional series throughout the 1950s often employed on light and entertainment programs as a storyteller such as in Pass the Salt; or as a commentator on local events.
A natural mimic and impersonator, Morris first appeared on television as The Hot Chestnut Man, a short slot in which he was shown sitting roasting the chestnuts, he would tell a humorous yarn in a West Country accent, often ending with a moral.
In 1960 he narrated the imported, Canadian-produced Tales of the Riverbank series of stories about Hammy the Hamster, Roderick the Rat, GP the Guinea Pig, and their assorted animal friends along a riverbank. The show used slowed-down footage of real animals filmed doing humanised things such as driving a car or boat, and living in houses. In the 1960s Morris also narrated the first few of The Railway Stories, recordings of the Railway Series books by the Rev. W. Awdry."
"A farm manager in Wiltshire for thirteen years,[2] Morris was discovered telling stories in a pub by the then BBC Home Service West Regional producer Desmond Hawkins. Morris made his radio debut in 1946, and featured in a number of Regional series throughout the 1950s often employed on light and entertainment programs as a storyteller such as in Pass the Salt; or as a commentator on local events.
A natural mimic and impersonator, Morris first appeared on television as The Hot Chestnut Man, a short slot in which he was shown sitting roasting the chestnuts, he would tell a humorous yarn in a West Country accent, often ending with a moral.
In 1960 he narrated the imported, Canadian-produced Tales of the Riverbank series of stories about Hammy the Hamster, Roderick the Rat, GP the Guinea Pig, and their assorted animal friends along a riverbank. The show used slowed-down footage of real animals filmed doing humanised things such as driving a car or boat, and living in houses. In the 1960s Morris also narrated the first few of The Railway Stories, recordings of the Railway Series books by the Rev. W. Awdry."
