A humdinger
 

I had an interesting sail today, and I thought that I should share it.
During the last six months I've picked up various tips from the posters
here. I've been waiting for a chance to try out the suggestions.

HW was at 15:30, so we were a bit limited in our choice of destinations. We
decided to go to Wooton Creek for lunch.


Normally, this would have involved a 75 minute sail there, and a 75 minute
sail back.

There wasn't much wind for the outward journey. We had 8 kts and, as usual
it was on the nose!!!

Fortunately, we had departed early, so we sailed for a while. We made
between 1.5 and 3 kts. I played with the travellor position. I set it much
lower than I used to. I can report that we didn't go any slower.

On the way home, we decided to try the spinaker. There was 8 kts of wind
when we started to rig the boat. By the time that we had the spinaker
lines rigged, the wind had risen to 15 kts. It had also shifted direction
..... big time! We decided to try the spin anyway. So we spent an hour
sailing in *slightly* the wrong direction. Eventually, we took the
spinaker in, and set course for home. The wind was now just off the nose!!
We had a fantastic beat home for the last hour.

Regards


Donal
--

A humdinger
 

What kind of boat were you sailing?

A humdinger
 

EdGordonRN wrote:
What kind of boat were you sailing?
Beneteau First 337.

http://www.lanode.com/priv/setanta/


Regards


Donal
--

A humdinger
 

Donal wrote:

There wasn't much wind for the outward journey. We had 8 kts and, as usual
it was on the nose!!!

Fortunately, we had departed early, so we sailed for a while. We made
between 1.5 and 3 kts. I played with the travellor position. I set it much
lower than I used to. I can report that we didn't go any slower.

Why would you want to set the traveller lower? That's usually done to
depower the main, which doesn't seem to be what you were after.

I can understand travelling the main down in a drifter to flatten the
sail, but 8kts shouldn't be low enough that you would want to flatten -
seems to me you should be powering up. What gives?

--
//-Walt
//
// http://cagle.slate.msn.com/working/040514/matson.gif

A humdinger
 

Walt wrote:


Why would you want to set the traveller lower? That's usually done to
depower the main, which doesn't seem to be what you were after.

I can understand travelling the main down in a drifter to flatten the
sail, but 8kts shouldn't be low enough that you would want to flatten -
seems to me you should be powering up. What gives?


I'm not very good at sail trim.

During the winter, there was some discussion here about travellor
position. It seems that I have been setting it too high. I've been
looking forward to doing some trials. However, it isn't easy in a 32 ft
boat in the Solent - the boat is too slow to respond, and the wind is
too variable. I used to set the travellor above the centreline, so that
the boom was actually on the centreline. Yesterday, I dropped the
travellor to about 4 inches below th c/l.

Also, the 8kts was the true wind speed, so we had about 10 over the deck.


Regards


Donal
--

A humdinger
 

"Donal" wrote:

We decided to go to Wooton Creek for lunch.

Normally, this would have involved a 75 minute sail there, and a 75 minute
sail back.There wasn't much wind for the outward journey. We had 8 kts
and, as usual
it was on the nose!!!

Sounds like an adventure from "Swallows and Amazons"!

Seahag

A humdinger
 

Donal wrote:
Walt wrote:

Why would you want to set the traveller lower? That's usually done to
depower the main, which doesn't seem to be what you were after.

I can understand travelling the main down in a drifter to flatten the
sail, but 8kts shouldn't be low enough that you would want to flatten -
seems to me you should be powering up. What gives?

I'm not very good at sail trim.

I don't know that I am either, but here's my $.02:

Most of the time you just set the traveler in the middle, and trim the
mainsheet as needed. With the traveler in the middle, sheeting the
sail all the way in brings the boom to the centerline - probably over
trimmed for most situations, so it's rare to sheet in all the way when
the traveler is in the middle.

With the traveler let down somewhat ( a dozen cm for a dinghy,more for
a boat your size) as you sheet in hard the boom doesn't come all the
way to the centerline - it only comes in as far as the traveler
position. At that point, sheeting in harder doesn't pull the boom in
- it pulls it down, flattening the mainsail, bending the mast, and
depowering the rig.

So I view the traveler as a way to depower when beating in higher winds.


During the winter, there was some discussion here about travellor
position. It seems that I have been setting it too high. I've been
looking forward to doing some trials. However, it isn't easy in a 32 ft
boat in the Solent - the boat is too slow to respond, and the wind is
too variable. I used to set the travellor above the centreline, so that
the boom was actually on the centreline. Yesterday, I dropped the
travellor to about 4 inches below th c/l.

Pulling the boom all the way to the centerline is probably over
trimming in most situations, so letting the traveler down was likely
an improvement, even if you let it down too far. That said, we're
probably talking about speed differences of a boat-length or two per
mile - vitally important if you're racing, irrelevant if you're not.

Also, the 8kts was the true wind speed, so we had about 10 over the deck.

8 kts is borderline planing conditions for me. Not light air at all.
Much more (well, twice as much) and effective depowering is the
difference between staying upright and going for a swim.


--
// Walt
//
// There is no Volkl Conspiracy

A humdinger
 

Walt wrote:

Donal wrote:

Walt wrote:


Why would you want to set the traveller lower? That's usually done to
depower the main, which doesn't seem to be what you were after.

I can understand travelling the main down in a drifter to flatten the
sail, but 8kts shouldn't be low enough that you would want to flatten -
seems to me you should be powering up. What gives?

I'm not very good at sail trim.


I don't know that I am either, but here's my $.02:

Most of the time you just set the traveler in the middle, and trim the
mainsheet as needed. With the traveler in the middle, sheeting the
sail all the way in brings the boom to the centerline - probably over
trimmed for most situations, so it's rare to sheet in all the way when
the traveler is in the middle.

With the traveler let down somewhat ( a dozen cm for a dinghy,more for a
boat your size) as you sheet in hard the boom doesn't come all the way
to the centerline - it only comes in as far as the traveler position.
At that point, sheeting in harder doesn't pull the boom in - it pulls it
down, flattening the mainsail, bending the mast, and depowering the rig.

My 2c

It may 'depower', but it would do so at the expense of efficiency by
closing the leech. The best way to bend the mast is with backstay
tension. This will flatten the sail without closing the leech. To
depower you really need the leech to open and use a Cunningham to help
flatten. Think of the traveller as being used to help control the leech
and it works in harmony with the mainsheet. Once the traveller
adjustment is all used up you really need the vang to help control the
leech. I suggest you should only bring the boom to centerline if you
have correct twist and then the traveller will be generally above
centerine a bit (I'm assuming well cut sails).

Cheers

A humdinger
 

Navigator wrote:
It may 'depower', but it would do so at the expense of efficiency by
closing the leech.

Or, on the other hand, it may not close the leach.

All sails are not cut the same, all rigs do not respond the same.

... The best way to bend the mast is with backstay
tension.

Depends on the rig.

This will flatten the sail without closing the leech. To
depower you really need the leech to open and use a Cunningham to help
flatten.

The cunningham does nothing to flatten the sail. The cunningham pulls
draft forward.

Once again your advice is a worthless mish-mash of overgeneralization &
misinformation. It's kind of like insisting that you were in Boston, and
know all about it, when you were actually in Baltimore.

Fresh Breezes- Doug King

A humdinger
 

Walt wrote:
I don't know that I am either, but here's my $.02:

Most of the time you just set the traveler in the middle, and trim the
mainsheet as needed. With the traveler in the middle, sheeting the
sail all the way in brings the boom to the centerline - probably over
trimmed for most situations, so it's rare to sheet in all the way when
the traveler is in the middle.

Somewhat agreed, but you're not going to centerline the boom with the
traveler in the middle. Even if the sheet is pulled very tight, you'll
have to pull the traveller up at least a little bit to get the boom on
centerline.

The thing to remember is that the relative angle of the sail to the boat
is what's important. Always look up past the boom... the top batten is a
good indicator...


With the traveler let down somewhat ( a dozen cm for a dinghy,more for a
boat your size) as you sheet in hard the boom doesn't come all the way
to the centerline - it only comes in as far as the traveler position.
At that point, sheeting in harder doesn't pull the boom in - it pulls it
down, flattening the mainsail, bending the mast, and depowering the rig.

So I view the traveler as a way to depower when beating in higher winds.

Right... the traveller lets the main out without letting the upper
section get all floppy. The important thing here is that easing the
traveller instead of the sheet keeps the twist constant, and for
fractional rigs and/or backstayless rigs (like dinghies) it keeps the
jib luff tension more consistant.


Pulling the boom all the way to the centerline is probably over trimming
in most situations, so letting the traveler down was likely an
improvement, even if you let it down too far.

I dunno, lots of keelboats can carry the boom at or slightly above
centerline. Depends on the conditions and what he was trying to do. If
the boat's not overpowered then letting the traveller down is probably
not the thing to do.

... That said, we're probably
talking about speed differences of a boat-length or two per mile -
vitally important if you're racing, irrelevant if you're not.

I disagree... especially if pointing is an issue. The difference in
speed can be large, and with the effect on pointing, the difference VMG
to windward can be huge... several minutes per mile.


Also, the 8kts was the true wind speed, so we had about 10 over the deck.


8 kts is borderline planing conditions for me. Not light air at all.
Much more (well, twice as much) and effective depowering is the
difference between staying upright and going for a swim.

Here's where it's important to know the individual characteristics of
the boat. Walt, you're singlehanding an Albacore? I don't know much
about Donal's boat, I have raced a Beneteau First 34/7.

Fresh Breezes- Doug King

A humdinger
 

"DSK" wrote in message
...
Walt wrote:
[snip]

The thing to remember is that the relative angle of the sail to the boat
is what's important. Always look up past the boom... the top batten is a
good indicator...

Could you expand on this, please?


[snip]

So I view the traveler as a way to depower when beating in higher winds.

Right... the traveller lets the main out without letting the upper
section get all floppy. The important thing here is that easing the
traveller instead of the sheet keeps the twist constant, and for
fractional rigs and/or backstayless rigs (like dinghies) it keeps the
jib luff tension more consistant.

Understood!




Pulling the boom all the way to the centerline is probably over trimming
in most situations, so letting the traveler down was likely an
improvement, even if you let it down too far.

I dunno, lots of keelboats can carry the boom at or slightly above
centerline. Depends on the conditions and what he was trying to do. If
the boat's not overpowered then letting the traveller down is probably
not the thing to do.

Hmmmm....

At the weekend, on our final leg with 15 kts(T) forward of the beam, the
boat *felt* right.

I had the travellor set about 6" below the centreline, and we were sheeted
in hard. Previously, I would have had the travellor *on* the centreline -
or maybe a little above it.


It's odd, but I find the nav, and boat handling a piece of cake. Efficient
sail trim is still a bit of a black art!


Regards


Donal
--

A humdinger
 

DSK wrote:
Navigator wrote:

It may 'depower', but it would do so at the expense of efficiency by
closing the leech.


Or, on the other hand, it may not close the leach.

All sails are not cut the same, all rigs do not respond the same.

... The best way to bend the mast is with backstay

tension.


Depends on the rig.

This will flatten the sail without closing the leech. To depower you
really need the leech to open and use a Cunningham to help flatten.


The cunningham does nothing to flatten the sail. The cunningham pulls
draft forward.

Once again your advice is a worthless mish-mash of overgeneralization &
misinformation. It's kind of like insisting that you were in Boston, and
know all about it, when you were actually in Baltimore.


Well of course your must me right Doug 'cos Melges and poor old Nav
know nothing:

Melges:

Cunningham: Remove all horizontal wrinkles, in the heavier puffs pull
very hard to bend the mast which will flatten the sail and twist open
the top batten


Back to school for you Doug. Bwhahahhahahahah

Cheers

A humdinger
 

DSK wrote:

Walt wrote:

I don't know that I am either, but here's my $.02:

Most of the time you just set the traveler in the middle, and trim the
mainsheet as needed. With the traveler in the middle, sheeting the
sail all the way in brings the boom to the centerline - probably over
trimmed for most situations, so it's rare to sheet in all the way when
the traveler is in the middle.


Somewhat agreed, but you're not going to centerline the boom with the
traveler in the middle. Even if the sheet is pulled very tight, you'll
have to pull the traveller up at least a little bit to get the boom on
centerline.


Glad to see you're learning from me Doug.

Cheers

A humdinger
 

Navigator wrote:
Melges:

Cunningham: Remove all horizontal wrinkles, in the heavier puffs pull
very hard to bend the mast which will flatten the sail and twist open
the top batten

???

Bending the mast with the cunningham... on monohulls with more or less
conventional rigs... is a new one on me. Cats use what is basically a
very powerful cunningham to bend the mast, but their rigs are very
different.



Back to school for you Doug. Bwhahahhahahahah

Yep. Always something new to learn... that's one of the differences
between me & you, Navvie... I am learning new stuff all the time, you
are convinced you already know everything. Maybe you got so smart from
watching TV, like Boobsie?

DSK

A humdinger
 

On Thu, 27 May 2004 12:02:09 +1200, something compelled Navigator
, to say:

Cunningham: Remove all horizontal wrinkles, in the heavier puffs pull
very hard to bend the mast which will flatten the sail and twist open
the top batten

I thought the purpose of a cunningham was to tension the luff
past what is possible with just the halyard. Sounds like
something you'd do in high wind.

A humdinger
 

DSK wrote:

Navigator wrote:

Melges:

Cunningham: Remove all horizontal wrinkles, in the heavier puffs pull
very hard to bend the mast which will flatten the sail and twist open
the top batten


???

Bending the mast with the cunningham... on monohulls with more or less
conventional rigs... is a new one on me. Cats use what is basically a
very powerful cunningham to bend the mast, but their rigs are very
different.


But a good dinghy sailor should have known this. Regardless of what you
may say, the cunnignham will always flatten the sail.


Back to school for you Doug. Bwhahahhahahahah


Yep. Always something new to learn... that's one of the differences
between me & you, Navvie... I am learning new stuff all the time, you
are convinced you already know everything. Maybe you got so smart from
watching TV, like Boobsie?


You are such a bad loser.

Cheers

A humdinger
 

Steve Daniels, Seek of Spam wrote:

On Thu, 27 May 2004 12:02:09 +1200, something compelled Navigator
, to say:


Cunningham: Remove all horizontal wrinkles, in the heavier puffs pull
very hard to bend the mast which will flatten the sail and twist open
the top batten


I thought the purpose of a cunningham was to tension the luff
past what is possible with just the halyard. Sounds like
something you'd do in high wind.

Yes, it also helps control draft (as Doug said) which on older and
(especially on) non-high tech sails has the nasty habit of moving aft a
lot as wind load increases


Cheers.

A humdinger
 

Navigator wrote:
But a good dinghy sailor should have known this. Regardless of what you
may say, the cunnignham will always flatten the sail.

Not that I've ever seen or heard before. One quote, out of context,
doesn't prove anything. OTOH maybe cunninghams work differently down there?


You are such a bad loser.

Not really. It's just that you are so desperate to prove you "know"
something... anything...

When you figure out the difference between Baltimore & Boston, let us
know, OK?

DSK

A humdinger
 

OzOne wrote:
Wouldn't want to try bending the mast with cunningham on Navvys boat.

Careful, Oz, next he'll be calling you a sore loser!

I wonder if you should adjust the runners before bending the mast with
the cunningham? ;)

DSK

A humdinger
 

OzOne wrote in message ...
On Wed, 26 May 2004 22:55:10 +0100, "Donal"
scribbled thusly:


"DSK" wrote in message
.. .
Walt wrote:
[snip]

The thing to remember is that the relative angle of the sail to the
boat
is what's important. Always look up past the boom... the top batten is
a
good indicator...

Could you expand on this, please?


Donal. if you go here
http://www.northsailsod.com/class/et...ls_tuning.html

There's a pretty good outline of our tuning procedure.

Thanks. I've read it ... and I'll read it again.


Look at the chart for mainsail tune and note that we rely a lot on top
batten to indicate position of the leech on the rest of the sail.
Closed leech will help us climb in anything above light air up to a
fresh breeze.
In light it's laid off to promote flow and reduce stalling, Heavy it's
open to ease leech pressure.

BTW this is a North guide, my setup is a little different.
Note just how finicky the Etchells is to setup and YES, we do change
the entire rig setup every race.

That web page gave me the impression that you had to adjust the mast rake
*during* some races!!

Regards


Donal
--

A humdinger
 

OzOne wrote:
On Thu, 27 May 2004 17:46:20 +1200, Navigator
scribbled thusly:



But a good dinghy sailor should have known this. Regardless of what you
may say, the cunnignham will always flatten the sail.



Nope, sorry Nav, it won't "always" flatten the sail.
It will draw the draft forward to make the sail appear flatter to the
wind and will certainly flatten the sail when "pulled very hard" to
induce mast bend.


S'funny how you keep saying flatten... It wall also remove horizontal
wrinkles... That's flattening too.

Cheers

A humdinger
 

OzOne wrote:

On Wed, 26 May 2004 21:07:34 -0400, DSK
scribbled thusly:



Bending the mast with the cunningham... on monohulls with more or less
conventional rigs... is a new one on me. Cats use what is basically a
very powerful cunningham to bend the mast, but their rigs are very
different.



Wouldn't want to try bending the mast with cunningham on Navvys boat.



Really? I use use the backstay actually as I said.

Cheers

A humdinger
 

DSK wrote:

OzOne wrote:

Wouldn't want to try bending the mast with cunningham on Navvys boat.


Careful, Oz, next he'll be calling you a sore loser!

I wonder if you should adjust the runners before bending the mast with
the cunningham? ;)


So, you've never used a cunningham to bend the mast or flatten the sail
on any of the hundreds of boat you've sail so expertly. Interesting.


Cheers

A humdinger
 

OzOne wrote:

On Thu, 27 May 2004 23:41:38 +0100, "Donal"
scribbled thusly:

That web page gave me the impression that you had to adjust the mast rake
*during* some races!!

It's illegal to move the mast butt during a race.


Oz1...of the 3 twins.

What's a "mast butt"?

LP (on topic for once)

A humdinger
 

OzOne wrote:

On Fri, 28 May 2004 00:22:31 -0500, "Lady Pilot"
scribbled thusly:


OzOne wrote:

On Thu, 27 May 2004 23:41:38 +0100, "Donal"
scribbled thusly:

That web page gave me the impression that you had to adjust the mast
rake
*during* some races!!

It's illegal to move the mast butt during a race.


Oz1...of the 3 twins.

What's a "mast butt"?

LP (on topic for once)


The base of the mast.
It fits into a step that has a slide attached so the stepping position
can be moved fore and aft thru about a 6" range by turning a
jackscrew.
It gives us the ability to alter the mast rake according to the
conditions to better balance the boat with a given sail setup.

I think if you would explain this while I was onboard, I could grasp it
without a problem.. I understand logically...but practical always beats
*it* out...

Thanks for the explanation,

LP

A humdinger
 

Navigator wrote:
So, you've never used a cunningham to bend the mast

On beach cats, sure. But they call it a downhaul, and the rig is quite
different.

... or flatten the sail

No. The cunningham doesn't flatten the sail...

although your little twist about removing wrinkles, I suppose that is
flattening the sail, just like an iron "flattens" a shirt.

Bending the mast flattens the sail. It also moves draft aft, so most
often the cunningham is used to pull draft forward again.


on any of the hundreds of boat you've sail so expertly. Interesting.

Do you really find expert sailing interesting? It appears you are mostly
interested in pedantry.

DSK

A humdinger
 

"Lady Pilot" wrote in message
| Thanks for the explanation,

Well Darlin' .... I may not be able to "adjust my Mast Butt".... but I can
assure you it wouldn't be noticed while the whales are breaching off the
starboard bow on a navy blue sea with emerald islands beckoning you with
their white sand beaches.

CM

Yup... 3 sheets to the wind... but I've earned every drink this week. ;-D

CM

A humdinger
 

Look at the chart for mainsail tune and note that we rely a lot on top
batten to indicate position of the leech on the rest of the sail.
Closed leech will help us climb in anything above light air up to a
fresh breeze.
In light it's laid off to promote flow and reduce stalling, Heavy it's
open to ease leech pressure.

One thing that chart doesn't make clear- are they talking about angle
relative to the boom or to centerline of the boat?

Also important is what they say about the top leach telltale. This is
the key to air flow vs pressure. I think this is going to be a good
starting guide for any boat with roughly similar aspect ratio & SA/D
ratio to the Etchells. I'm guessing Donal's boat is heavier (but
possibly not that much so) and will want the top leach telltale stalling
a little more of the time.


BTW this is a North guide, my setup is a little different.
Note just how finicky the Etchells is to setup and YES, we do change
the entire rig setup every race.

A lot of work, eh? But you can always race Lasers if you get sick of it!


Donal wrote:
That web page gave me the impression that you had to adjust the mast rake
*during* some races!!

AFAIK that's illegal. You want the mast raked going upwind, standing up
straight or even raked forward going downwind. Some early IMS boats had
mast butt rams with about 3' of throw, I know of one that had a hinge to
achieve this.

I don't know why so many classes make this illegal, other than it's an
expensive PITA and puts the whole rig at risks. But no clases I can
think of allow you to move the mast step during a race and rather few
allow adjusting the partners... apparently Etchells do... don't know if
you're allowed a "puller," Lightnings ruled this illegal and the class
has to restate the rule every few years as people cleverly invent new
ways to do it.

Donal I wanted to read Oz's link before commenting further. It looks
like a great guideline for a fast keelboat, except that they apparently
pull the backstay on rather early. If you get the leach telltales
working like they say, then use the traveler to control heel & helm,
you'll be either right in the groove or pretty darn close. I like to
leave the backstay off until the traveler is way down but it's something
to experiement with.

Fresh Breezes- Doug King

A humdinger
 

"Capt. Mooron" wrote:

Well Darlin' .... I may not be able to "adjust my Mast Butt".... but I can
assure you it wouldn't be noticed while the whales are breaching off the
starboard bow on a navy blue sea with emerald islands beckoning you with
their white sand beaches.

Of course, I'm sure I wouldn't notice. When would be convenient for you?
;-)

LP

A humdinger
 

"Lady Pilot" wrote in message

| Of course, I'm sure I wouldn't notice. When would be convenient for you?
| ;-)

It's not me I'm aiming to please Darlin.......... ;-)

CM

A humdinger
 

OzOne wrote:


Our backstays have a huge range, downwind the chocks come out at the
front of the mast and it's allowed to crank waaaay forward. Some go
into reverse bend but IMHO that's slower.


I'd say mast inveresion is not a good idea. Do people ever break masts?
I'd think that moving the mast past vertical forward would reduce sail
efficiency downwind by promoting upward flow...?

Cheers

A humdinger
 

... I'm guessing Donal's boat is heavier (but
possibly not that much so) and will want the top leach telltale stalling
a little more of the time.

OzOne wrote:
Works pretty much the same for any easily driven boat.
Donals benny fit in here as do most fin keelers.

The percent time spent with the leach telltales backwinding? IMHO the
ideal varies with type/category of boat, but I'm not really sure what
the determining factors are. Some boats I've sailed that were
magnificent at pinching, got best VMG (in relatively smooth water) with
the leach telltale backed about 75% of the time. OTOH lightweight boats
with high aspect ratio do better with the leach telltale backwinding 10%
of the time.

The leach telltale backwinding shows that the differential pressure
across the sail has increased to the point where flow off the leach is
yanked backwards. DP is what drives the boat, ideally you'd want the
leach telltale *just about* to backwind but not actually doing it. Maybe
we need some kind of aero smoke trail prodcut derived from resublimated
thiotimoline.



BTW this is a North guide, my setup is a little different.
Note just how finicky the Etchells is to setup and YES, we do change
the entire rig setup every race.

What kind of sails do you use? Most of the one designers here use North
but the smaller shops do have inroads in some of the classes




Our backstays have a huge range, downwind the chocks come out at the
front of the mast and it's allowed to crank waaaay forward. Some go
into reverse bend but IMHO that's slower.

Kinda risky too, I'd think. Is the forward end of the mast partners flat
or contoured to match the mast?


We have a puller to pull the mast forwar and the same system can work
in reverse to pull it back. You cannot have cleats on the lines,
they're used only to alter the chocking at the partners.

Interesting way of regulating the tuning.

... We use multi
stepped nylon block here controlled by yet another string.

Same here, although I molded a set of epoxy blocks with a graphite
finish. The steps are 10, 5, and 2 mm... they're light & slick...
everybody wanted me to make them a set too, great for psyching peole out
in the parking lot!



Backstay does come on pretty early, it's essential to control forestay
sag in such a high pointing boat. Mainsails are cut pretty tight
leeched up high and respond t the backstay by opening up.
Ya gotta be real careful here because again, we need he leech pressure
to drive us high.

What do you mean by 'leach pressure'?


I learned more in my first 3 months in a Etchells about tune and rig
setup than I've ever learned in a season in anything else.

After reading the class tuning guide they sound very very sensitive.

Fresh Breezes- Doug King

A humdinger
 

DSK wrote:



The leach telltale backwinding shows that the differential pressure
across the sail has increased to the point where flow off the leach is
yanked backwards.

That'll be 'yankee' for leeward flow separation.

Cheers