What makes a boat weatherly?
 

Donal wrote:

It was February,
and we were beating into an F5 under sail and 50 hp engine.

Why the engine? F5 should be good sailing conditions for that boat?

Cheers MC

What makes a boat weatherly?
 

"MC" wrote in message
...


Donal wrote:

It was February,
and we were beating into an F5 under sail and 50 hp engine.

Why the engine? F5 should be good sailing conditions for that boat?

Hmmm!

The boat was a centre cockpit Barvaria 42. The wind was a very cold
easterly(4-6C). The owner had his wife aboard. She was diagnosed with
bronchitis a week later, and it took her a couple of months to recover.

The wind was almost dead on the nose, and the decision to motor made sense
at the time. In Setanta, I would have sailed further off the wind. I
might also have had the engine on (depending on time and tide constraints).
Setanta would definitely have slammed a lot more.



Regards


Donal
--

What makes a boat weatherly?
 

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

What makes a boat weatherly?
 

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

What makes a boat weatherly?
 

Strangly,
That is not at quite what the towing tank data work here says.
For a conventional vessle sailing in moderate conditions with a slight
weather helm (Ra 3).
Yes, the rudder has a lift component to weather and it is most typically
below the center of bouyancy.
If the rudder provided significant hydrodynamic lift and the keel did
not: then the foil section for the keel would have no advangage and
vessles otherwise equal varying only in draft would be substantially
equal performers. I can demonstrate that this is not the case.
Also: the only attack angle control for the keel would be the slip angle
(leeway) and this is negative, so there would be no value in trying to
use boat speed to reduce the slip angle.
Matt Colie (see prior sigs)

MC wrote:
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

What makes a boat weatherly?
 

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

What makes a boat weatherly?
 

DSK wrote:

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.


Ignoring your usual childish ad hominem, I wonder why did you say that
straightening the mast makes a boat more weatherly?

Cheers

What makes a boat weatherly?
 

Matt Colie wrote:

Strangly,
That is not at quite what the towing tank data work here says.
For a conventional vessle sailing in moderate conditions with a slight
weather helm (Ra 3).
Yes, the rudder has a lift component to weather and it is most typically
below the center of bouyancy.

So now we agree.

If the rudder provided significant hydrodynamic lift and the keel did
not: then the foil section for the keel would have no advangage and
vessles otherwise equal varying only in draft would be substantially
equal performers.

I think you've evaded the point. Of course the keel provides most of the
lift but the rudder dfoes add some -right? Remember even a small gain
wins races to windward!

Cheers MC

I can demonstrate that this is not the case.
Also: the only attack angle control for the keel would be the slip angle
(leeway) and this is negative, so there would be no value in trying to
use boat speed to reduce the slip angle.
Matt Colie (see prior sigs)

MC wrote:

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

What makes a boat weatherly?
 

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

What makes a boat weatherly?
 

DSK wrote

Frank Maier wrote:

Ole Thom pretty much answered for me. I've raced and cruised on both
masthead and fractional rigs. I guess I answered "masthead", assuming
as my default a full crew of experienced sailors who'd manually deal
with changing conditions on a constant basis. Then you don't need the
fractional rig to "automatically depower" for you.

Conventional wisdom has it that mast head rigs will point higher, and I think
that's true in ideal pointing conditions. But I think the frac rig is more
versatile.

Masthead rigs can also carry a bigger spinnaker
and go faster downwind.


heh heh the old Fredom 40 cat-ketch is one of my dream boats. They don't point
so high either, but it's a marvelous cruising rig. Sturdy and very easy to
handle.

I want to try one of those. They look like fun.


It's also a very good point that knowing how to get the optimum out of the rig
you have is more important than pining away for some theoretical ideal. There
are too many sailors who study teensy detailed ways of scrooching some small
improvement out of their boat, when their basic sailing methods are notably
below optimal. I remember acting as 'guest skipper' on a very nice European
designed and built racer-cruiser, a boat that should have had good performance
but usually did very poorly in casual races. The usual skipper stood at my
elbow and appeared to be very interested in how I drove the boat and had the
sails trimmed. He usally cranked everything in hard and made the boat heel
'way over, when I skippered we did much better. The next day, I was sailing on
another boat and he went back to doing the same old thing.... and was
complaining about it the rest of the season.

Lots of sailors jump into big boats and think
they know to sail them. The fact is they will
never get good, if the boat is forgiving.

Small boats make the sailor. If you learn on
a dinghy, and screw up, you end up in the water.
When you are wet, and cold, is it very obvious
which way the wind is coming from. I am still
amazed at the number of people, who can't tell
where the wind is coming from! I tell me
students if they screw that up, I'm dumping a
bucket of water on their heads to help them
learn. Threats seem to help.


Thom's keel mod is a good idea IMHO because he does not sail in the conditions
the boat was designed for, so it benefitted from increased keel area. For most
sailors, I don't think such a modification would be a good idea.

I'm not familiar with what Thom did, so I'll take
your word for it.


Bart Senior