MC wrote:

So, you don't understand why bending a mast can flatten the main?

No I understand it quite well. But it's pretty obvious that you understand very
little (in fact, nothing) about how to set up the basic tuning of a mast.

DSK

Doug you are talking about a mast
being straight side to side, and
of course you are correct that many
people don't get this right. For one
thing is a pain and take a lot of time
tweaking the shrouds.

MC is talking about mast bend as used
for sail shaping--another subject entirely.

Bart Senior


DSK wrote

MC wrote:

Doug, I am surprised at this comment and I'll disagree with it for a
number of reasons: Bending the mast aft can flatten the main.

That isn't what I was talking about. And the sail has to be cut to take the
mast bend into account, or it doesn't work.


So, the bottom line is that it may be quite inappropriate to straighten
the mast to make the boat weatherly.

Considering that you don't know that 20 doesn't equal 15, and from what you
have said about your racing results, you have a lot more to learn than to
teach.

DSK

N1EE wrote:

Doug you are talking about a mast
being straight side to side, and
of course you are correct that many
people don't get this right. For one
thing is a pain and take a lot of time
tweaking the shrouds.

If you know the method, it doesn't really take that much time. I think most
people don't approach it methodically and either make it worse or else fiddle
around forever. The important thing is to loosen all the lowers first and get the
masthead centered, few people seem willing to start by un-doing all previous mast
tuning.

It used to be that tuning manuals would talk about getting a uniform athwartships
bend to either open or close the slot, depending on whether the boat needed more
pointing or more power. But it has turned out that keeping the mast "in column"
meaning straight when viewed athwartship is faster. It may be that modern sails
(different cut & materials) respond enough differently that back then, the
side-to-side bend did help.... if you got it right...

We've had this demonstrated dramatically twice... once in the Lightning and once
in the Johnson 18. Somehow one lower shroud got tightened and I did not
scrupulously check the mast before setting out for the starting line. We could
point sort of OK on one tack, but terrible on the other, and despite all we could
do were sailing alongside the tail-enders. After spotting & fixing the problem
(which made me vow for the 100th time, always review the basics) we had front row
seats.




MC is talking about mast bend as used
for sail shaping--another subject entirely.

Yes, as usual he missed the point.

I think that it would be good to discuss mast bend & rake, too. Then MC will get
to toss in his 2 cents (but he'll probably still be wrong).

Fresh Breezes- Doug King

MC wrote:

DSK wrote:




while most should know that the rake of the mast affects C of E and the
degree of weather helm, I'll guess that many do knot know that by giving
the boat some weather helm she climbs to windward better as the rudder
adds lift.


I believe this to be true for full keels, but how does it work with a fin keel?

Cheers
Marty

Same effect. It adds lift.

Cheers MC

Martin Baxter wrote:
MC wrote:

DSK wrote:



while most should know that the rake of the mast affects C of E and the
degree of weather helm, I'll guess that many do knot know that by giving
the boat some weather helm she climbs to windward better as the rudder
adds lift.



I believe this to be true for full keels, but how does it work with a fin keel?

Cheers
Marty

Close, but not quite the case. The rudder can not provide any
significant lift on its own.
Any rudder angle adds drag and any rudder angle effects heal. Rudder to
correct weather helm increases healing monemt.
What is really happening is that the weather helm introduces an attack
angle for the keel. What you actually want to do is set the boat up to
balance with a heading that is a little higher than desired course.
When the rudder brings the track back to course, you are left with the
foil (keel)at a small attack angle. This works on all hulls, but is
most apparent on fin keel boats.
Matt Colie -www.yachtek.com


Martin Baxter wrote:
MC wrote:

DSK wrote:



while most should know that the rake of the mast affects C of E and the
degree of weather helm, I'll guess that many do knot know that by giving
the boat some weather helm she climbs to windward better as the rudder
adds lift.



I believe this to be true for full keels, but how does it work with a fin keel?

Cheers
Marty

No, I'm afraid you are wrong. The turning moment which causes the boat
to heel has a component to windward. If the rudder is neutral it adds no
lift of couse and is simply feathered in the water flow. Perhaps you
might like to consider the rudder as a wing: the angle of attack to the
water flow causes lift (and drag)?

Cheers



Matt Colie wrote:

Close, but not quite the case. The rudder can not provide any
significant lift on its own.
Any rudder angle adds drag and any rudder angle effects heal. Rudder to
correct weather helm increases healing monemt.
What is really happening is that the weather helm introduces an attack
angle for the keel. What you actually want to do is set the boat up to
balance with a heading that is a little higher than desired course. When
the rudder brings the track back to course, you are left with the foil
(keel)at a small attack angle. This works on all hulls, but is most
apparent on fin keel boats.
Matt Colie -www.yachtek.com


Martin Baxter wrote:

MC wrote:

DSK wrote:



while most should know that the rake of the mast affects C of E and the
degree of weather helm, I'll guess that many do knot know that by giving
the boat some weather helm she climbs to windward better as the rudder
adds lift.




I believe this to be true for full keels, but how does it work with a
fin keel?

Cheers
Marty

(N1EE) asked:
What makes a boat weatherly?
What is the best keel type, hull form, and rig type?
What can you do to improve weatherliness on an existing boat?
Back your answer with an explanation.

Generically speaking, assuming we're talking about existing production
boats and not esoteric drawing-board possibilites, I'd answer:

Dictionary def: Ability to sail close to the wind with little drift to
leeward.

Deep fin. Low wetted surface; low CsubP. Masthead sloop.

Depends on the boat; but... Always helps to: change to fresh sails;
use appropriate sails for conditions; trim properly. If it has a full
keel, high D/L ratio, low aspect ratio, multiple masts, or similar, ya
just hafta sell it and buy something else.

Physics.

Frank Maier) wrote:
....snip...

Self-followup. I posted before seeing Doug's comments. Ignore mine and
just read his.

(Frank Maier) wrote

(N1EE) asked:
What makes a boat weatherly?
What is the best keel type, hull form, and rig type?

Dictionary def: Ability to sail close to the wind with little drift to
leeward.

Deep fin. Low wetted surface; low CsubP. Masthead sloop.

I would think a fractional rig would perform better upwind
because of the increased options for sail shaping.

Why did you choose a masthead sloop?

Bart Senior