Hey simple!
 

Here's a well cut main in light airs.

http://community.webshots.com/photo/...56514380nkBEsE

Cheers MC

Hey simple!
 

Gee, I thought this main looked pretty good in light air.

Click he SAILLOCO'S Page
S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Sorry

http://journals.aol.com/sailloco/SAILLOCOSPage/
S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Sorry

http://journals.aol.com/sailloco/SAILLOCOSPage/

Good lord. There's not one pleasing line on that sailing brick!

RB

Hey simple!
 

The navigator© wrote:

Here's a well cut main in light airs.

http://community.webshots.com/photo/...56514380nkBEsE

Draft too far forward (unless you're just coming out of some
chop, which doesn't look to be the case)

Not enough draft in upper sections

Leach closed.

Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Fresh Breezes- Doug King

Hey simple!
 

Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Not sure what you mean. The wires are inside the radar support tube.

RB

Hey simple!
 

Not enough draft in upper sections

Leach closed.

Correct. Traveller is wrong for current course.

RB

Hey simple!
 

Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?.

I don't have a backstay antenna. What makes you think I do?
S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

You've got the crap dragged out of it!

Well I'm at a loss as to what that means.


S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Draft too far forward (unless you're just coming out of some
chop, which doesn't look to be the case)

Gee it looks like 45% aft of the stick to me.

Not enough draft in upper sections

It's a brand new main. They cut them much flatter nowadays.

Leach closed..

Kinda hard to tell that from where your sitting. I was trimming the main
and the top batten was parallel to the boom. It was really light air.
S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Correct. Traveller is wrong for current course.

LOL.......... How would you know? Traveler was above the centerline. Boom was
in the middle of the boat.
S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Good lord. There's not one pleasing line on that sailing brick!

It does have a pretty ass end. Tee hee.


S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Good lord. There's not one pleasing line on that sailing brick!

It does have a pretty ass end. Tee hee.

Looks more like an iron than a boat.

RB

Hey simple!
 

SAIL LOCO wrote:


Kinda hard to tell that from where your sitting. I was trimming the main
and the top batten was parallel to the boom. It was really light air.

Loco, I was offering critique of Navvie's 'perfectly' set & shaped main. For
some reason AOL will not let me look at your pictures.

For the leach, I like to look at the leach ribbons and the overall twist.
Sometimes it is hard to tell. In Navvie's pic you can't see the leach ribbons
(are they blue, for some reason? Are they missing?) but it looks like there is
no twist at all.

Fresh Breezes- Doug King

Hey simple!
 

DSK wrote:


The navigator© wrote:


Here's a well cut main in light airs.

http://community.webshots.com/photo/...56514380nkBEsE


Draft too far forward (unless you're just coming out of some
chop, which doesn't look to be the case)

Not enough draft in upper sections

You must be used to really baggy sails.

Leach closed.

No it isn't. You cant tell the twist from that camer angle

Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Well spotted. The wire is off.

Cheers MC

Hey simple!
 

Don't be silly, look at the the tell tales.

Cheers MC

Bobsprit wrote:

Not enough draft in upper sections

Leach closed.

Correct. Traveller is wrong for current course.

RB

Hey simple!
 

Doug can see the traveller!???

Cheers MC

Bobsprit wrote:

Not enough draft in upper sections

Leach closed.

Correct. Traveller is wrong for current course.

RB

Hey simple!
 

Look more carefully. There are ribbons at each battenb and they are all
flying at that moment. You simply can't see twist from that camera angle
so the twist must be sufficient to keep the top ribbons flying...

Cheers MC

DSK wrote:

SAIL LOCO wrote:


Kinda hard to tell that from where your sitting. I was trimming the main
and the top batten was parallel to the boom. It was really light air.


Loco, I was offering critique of Navvie's 'perfectly' set & shaped main. For
some reason AOL will not let me look at your pictures.

For the leach, I like to look at the leach ribbons and the overall twist.
Sometimes it is hard to tell. In Navvie's pic you can't see the leach ribbons
(are they blue, for some reason? Are they missing?) but it looks like there is
no twist at all.

Fresh Breezes- Doug King

Hey simple!
 

Not enough draft in upper sections


The navigator© wrote:
You must be used to really baggy sails.

Actually, no. I'm used to lightweight dinghy where the max depth of
the chord is only 12%. But in this case, the issue isn't bagginess
at all. It is the simple fact that a well cut sail will be
relatively deeper in the upper sections.

In any event, in light air, a big round section with a relatively
flat entry will keep attached flow and build up much more power
than a draft forward conventional airfoil shape.




Leach closed.

No it isn't. You cant tell the twist from that camer angle

I can see the topping lift, whih is presumably straight, and the
distance from the battens to the topping lift does not appear to
increase towards the middle of the sail. Also, it appears (could be
due to camera angle) that all the battens are at the same angle.

Looking closely, I can see what might be leach ribbons flowing.
That's a good sign.




Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Well spotted. The wire is off.

OK, that's allowed ;)

Fresh Breezes- Doug King

Hey simple!
 

DSK wrote:

Not enough draft in upper sections


The navigator© wrote:
You must be used to really baggy sails.


Actually, no. I'm used to lightweight dinghy where the max depth of
the chord is only 12%. But in this case, the issue isn't bagginess
at all. It is the simple fact that a well cut sail will be
relatively deeper in the upper sections.

In any event, in light air, a big round section with a relatively
flat entry will keep attached flow and build up much more power
than a draft forward conventional airfoil shape.

There we disagree, in ligh airs the angle of attack of the leading
section must be close to zero to attach flow. Hence it should be full.
Surely you would agree that aeronautiucs shows that deeper foils
generate more lift at low speeds....





Leach closed.

No it isn't. You cant tell the twist from that camer angle


I can see the topping lift, whih is presumably straight, and the
distance from the battens to the topping lift does not appear to
increase towards the middle of the sail.

You are forgetting the roach...

Also, it appears (could be
due to camera angle) that all the battens are at the same angle.

Yes it's the camera angle. the top tell tale could not be flying at 33
deg app. if there was no twist.

Looking closely, I can see what might be leach ribbons flowing.
That's a good sign.

Yes they are, and it is.


Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Well spotted. The wire is off.


OK, that's allowed ;)

It's a good idea until you go offshore. Means that the connections don't
'weather' until they are needed.

Cheers MC

Hey simple!
 

It's far from simple. In the upper sections, leech control is critical
to determine how much draft is right. As wind velocities at the top are
higher and if angles of attack are set to be optimal by twist control
then the upper secion should be slightly flatter. This is possible
enitirely due to the stiffness of modern fabrics that will properly
support their leech as the wind pressure increases. Have a look at the
North web site for some photos of their racing sails and try to find
full upper sections.

Cheers MC

DSK wrote:

It is the simple fact that a well cut sail will be
relatively deeper in the upper sections.

Hey simple!
 

You are 100 percent wrong with this observation.

Take a look at an albatross sailing on the air currents
above the ocean. If you perchance to see one end-on
you will note their wing tips flare upwards and outwards.

Picture one of the bird's wings placed vertically and you
will see how incorrect your trying to close the leech
of your sail is. This a common fallacy with those who
fancy themselves racers. They are too busy looking
at all the other racers doing it wrong and can't see
folly and inefficiency even when they look right at
it.

Another little mother nature test is try feeding some
seagulls sometimes. The few being fed will put out
the word and others from all around will come
barreling in. They approach at high speed. Then
they draw their wings in a nice curve effectively
shortening their wing span and they feather and
stall. This inefficiency acts like a brake. What
you do with a sail with a closed leech in lower
winds is stall the damned thing out.

S.Simon


"The_navigator©" wrote in message ...
It's far from simple. In the upper sections, leech control is critical
to determine how much draft is right. As wind velocities at the top are
higher and if angles of attack are set to be optimal by twist control
then the upper secion should be slightly flatter. This is possible
enitirely due to the stiffness of modern fabrics that will properly
support their leech as the wind pressure increases. Have a look at the
North web site for some photos of their racing sails and try to find
full upper sections.

Cheers MC

DSK wrote:

It is the simple fact that a well cut sail will be
relatively deeper in the upper sections.

Hey simple!
 

Simple Simon wrote:
You are 100 percent wrong with this observation.
What, twist control is wrong?

Bwhahahhaha

Cheers MC

Hey simple!
 

So why is your leech closed?

Cheers MC

Simple Simon wrote:

What
you do with a sail with a closed leech in lower
winds is stall the damned thing out.

Hey simple!
 

In any event, in light air, a big round section with a relatively
flat entry will keep attached flow and build up much more power
than a draft forward conventional airfoil shape.

The navigator© wrote:
There we disagree, in ligh airs the angle of attack of the leading
section must be close to zero to attach flow.

??? How do you get this out of what I said above?

Hence it should be full.

No. To keep flow attached (actually, to re-attach flow after passing the
mast) the leading section should be flatter further aft. Furthermore, at low
Reynolds numbers, the lift/drag ratio is better for the sort of shape I'm
describing.

This is one case where theory and practice seem to mesh pretty well. I read
a lot about new methods of sail trim and watched some of our competitors,
and found that what looked wrong (a deep round section) was actually quite
fast.




Surely you would agree that aeronautiucs shows that deeper foils
generate more lift at low speeds....

Again, how do you get this out of what I said?


I can see the topping lift, whih is presumably straight, and the
distance from the battens to the topping lift does not appear to
increase towards the middle of the sail.

You are forgetting the roach...


No I'm not, I'm looking at the angle of the battens. When a sail is twisted,
the battens take a series of angles as you look up the sail. Not exactly
rocket science.


Looking closely, I can see what might be leach ribbons flowing.
That's a good sign.

Yes they are, and it is.

Depends on the boat and the conditions. Some boats like the top telltale
flying all the time, some like it curling back some of the time, some more.

Usually boats that like to pinch (as opposed to boats that do better footing
off) want to have the upper leach ribbon curling back at least 25% of the
time, although in light air you have to be careful that the upper section
isn't stalling.




Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Well spotted. The wire is off.


OK, that's allowed ;)

It's a good idea until you go offshore. Means that the connections don't
'weather' until they are needed.

You need some No-Ox.

Fresh Breezes- Doug King

Hey simple!
 

Let me try to get this straigt. You are saying that a flat sail
generates more lift in lower winds than a full sail?

Cheers MC

DSK wrote:

No. To keep flow attached (actually, to re-attach flow after passing the
mast) the leading section should be flatter further aft. Furthermore, at low
Reynolds numbers, the lift/drag ratio is better for the sort of shape I'm
describing.

Hey simple!
 

You are saying that a flat sail
generates more lift in lower winds than a full sail?

The word here is "lift."
And we see that MC doesn't know what it means!

RB

Hey simple!
 

Loco, I was offering critique of Navvie's 'perfectly' set & shaped main.
For
some reason AOL will not let me look at your pictures.

For the leach, I like to look at the leach ribbons and the overall
twist.

Doug,
Oh sorry. BTW my tells are flying.


S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Look more carefully. There are ribbons at each battenb and they are all
flying at that moment. You simply can't see twist from that camera angle
so the twist must be sufficient to keep the top ribbons flying...

Correct.


S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

Take a look at an albatross sailing on the air currents above the ocean.

I don't go out that far.


S/V Express 30 "Ringmaster"
Trains are a winter sport

Hey simple!
 

I wonder if our disagreement arises because your theories are based on
ideas originating from the "eliptical wing" and a desire to make the
main adopt an eliptical shape as far as camber is concerned (by making
the top fuller)? Increasing fullness also helps solve the roach support
problem -which is offset in modern sails with full length battens and
stiffer fabrics. Some sudies (e.g. here at Auckland) have shown this is
not correct for high aspect roachy mains where the camber (and lift)
should be reduced at the top of the sail to reduce heeling moment. In
the extreme case, negative (!) camber could improve performance by
reducing the heeling of the vessel.. This is the basis for the flat top
sail whose design is carried to extreme in modern windsurf sails where
the top is completely flat and heavily battened to support a huge roach.

Cheers MC


DSK wrote:

In any event, in light air, a big round section with a relatively
flat entry will keep attached flow and build up much more power
than a draft forward conventional airfoil shape.

The navigator© wrote:
There we disagree, in ligh airs the angle of attack of the leading
section must be close to zero to attach flow.


??? How do you get this out of what I said above?


Hence it should be full.


No. To keep flow attached (actually, to re-attach flow after passing the
mast) the leading section should be flatter further aft. Furthermore, at low
Reynolds numbers, the lift/drag ratio is better for the sort of shape I'm
describing.

This is one case where theory and practice seem to mesh pretty well. I read
a lot about new methods of sail trim and watched some of our competitors,
and found that what looked wrong (a deep round section) was actually quite
fast.




Surely you would agree that aeronautiucs shows that deeper foils
generate more lift at low speeds....


Again, how do you get this out of what I said?


I can see the topping lift, whih is presumably straight, and the
distance from the battens to the topping lift does not appear to
increase towards the middle of the sail.

You are forgetting the roach...



No I'm not, I'm looking at the angle of the battens. When a sail is twisted,
the battens take a series of angles as you look up the sail. Not exactly
rocket science.


Looking closely, I can see what might be leach ribbons flowing.
That's a good sign.


Yes they are, and it is.


Depends on the boat and the conditions. Some boats like the top telltale
flying all the time, some like it curling back some of the time, some more.

Usually boats that like to pinch (as opposed to boats that do better footing
off) want to have the upper leach ribbon curling back at least 25% of the
time, although in light air you have to be careful that the upper section
isn't stalling.


Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Well spotted. The wire is off.


OK, that's allowed ;)

It's a good idea until you go offshore. Means that the connections don't
'weather' until they are needed.


You need some No-Ox.

Fresh Breezes- Doug King

Hey simple!
 

What do you mean, outhaul?

Cheers MC

Donals Delight. wrote:

On Mon, 24 Nov 2003 08:16:14 -0500, DSK
wrote:



The navigator© wrote:


Here's a well cut main in light airs.

http://community.webshots.com/photo/...56514380nkBEsE

Draft too far forward (unless you're just coming out of some
chop, which doesn't look to be the case)

Not enough draft in upper sections

Leach closed.

Why do you have a backstay antennae and no wire to it? Is the
wire lead up the mast and to the antennae at the top?

Fresh Breezes- Doug King


Yeah that's what I said....He's got the crap dragged out of it.


Oz1...of the 3 twins.

I welcome you to crackerbox palace,We've been expecting you.

Hey simple!
 

C'mon give the guy a break. It looks like too much outhaul and
vang/trveller downhaul on the boom. The leech is too closed... If you
opened the leech you would not have to let the traveller down in those airs.

Cheers MC

Donals Delight. wrote:

On 24 Nov 2003 16:33:22 GMT, (SAIL LOCO) wrote:


You've got the crap dragged out of it!

Well I'm at a loss as to what that means.


Figures!


Oz1...of the 3 twins.

I welcome you to crackerbox palace,We've been expecting you.

Hey simple!
 

Bobsprit wrote:

You are saying that a flat sail
generates more lift in lower winds than a full sail?

The word here is "lift."
And we see that Booby doesn't know what it means!

RB

Hey simple!
 

The navigator© wrote:

Let me try to get this straigt. You are saying that a flat sail
generates more lift in lower winds than a full sail?

No, I am not saying that and never did. I had the (perhaps mistaken) impression
that this discussion was about
1- variation in chord depth from middle to upper sections
2- where the best point of max draft
3- entry shape, which is a partially function of #2 above.

Would it be too much trouble to stick to one of these points?

Fresh Breezes- Doug King

Hey simple!
 

Well there seems to be a communication problem 'cos you said:

In any event, in light air, a big round section with a relatively
flat entry will keep attached flow and build up much more power
than a draft forward conventional airfoil shape.

I saw the "big round section" and "much more power" while you were
saying that flatter at the head was no good.

Cheers MC

DSK wrote:

The navigator© wrote:


Let me try to get this straigt. You are saying that a flat sail
generates more lift in lower winds than a full sail?


No, I am not saying that and never did. I had the (perhaps mistaken) impression
that this discussion was about
1- variation in chord depth from middle to upper sections
2- where the best point of max draft
3- entry shape, which is a partially function of #2 above.

Would it be too much trouble to stick to one of these points?

Fresh Breezes- Doug King

Hey simple!
 

"The_navigator©" wrote in message ...
I saw the "big round section" and "much more power" while you were
saying that flatter at the head was no good.


If a big round section produced horsepower than Bobsprit
can remove his mast and toss his sails. All he has to do is stand
on deck and expose his belly to the elements.

S.Simon

Hey simple!
 

"Simple Simon" wrote in message
...

"The_navigator©" wrote in message
...
I saw the "big round section" and "much more power" while you were
saying that flatter at the head was no good.


If a big round section produced horsepower than Bobsprit
can remove his mast and toss his sails. All he has to do is stand
on deck and expose his belly to the elements.


Bwahahaaa ... errrr .... no, I didn't laugh out loud at that!
[ahem]..[cough]




Regards


Donal
--

Hey simple!
 

The navigator© wrote:

I wonder if our disagreement arises because your theories are based on
ideas originating from the "eliptical wing" and a desire to make the
main adopt an eliptical shape as far as camber is concerned (by making
the top fuller)?

Huh? AFAIK the elliptical wing is usually referred to profile, not section shape.

So, I can definitely say, no that's not it.


Increasing fullness also helps solve the roach support
problem -which is offset in modern sails with full length battens and
stiffer fabrics. Some sudies (e.g. here at Auckland) have shown this is
not correct for high aspect roachy mains where the camber (and lift)
should be reduced at the top of the sail to reduce heeling moment.

Hello? Why are you talking about 'reducing heeling moment' in light air?

In
the extreme case, negative (!) camber could improve performance by
reducing the heeling of the vessel..

Yes it could, but not in light air.

Fresh Breezes- Doug King