Sailing Newbie Question

On 21 Nov 2004 12:18:14 -0800, sheepshaggerx.TakeThisOut@yahoo.co.uk (Love a
Sheep) wrote:

 >I am learning to sail and have a few questions. I understand that the
 >sails can act either as an airofoil (lile an aircraft wing) or like a
 >parachute where the wind simply blows the sail directly. My question
 >is this. If the wind is ahead of the beam ie we are sailing windward
 >then I expect that the airofoil principle must always hold there
 >otherwise we would be sailing backwards!
 >
 >However, if the wind is aft of the beam on say the starboard side then
 >surely we have a choice where to set the sails ie they can be on the
 >starboard side (ie the boom is pointing to the starboard side) where
 >they act as an airofoil or on the port side where they act as a
 >'parachute' - is this right or am I missing something. If so which is
 >best?
 >
 >Thanks

Using the aerofoil analogy, the mast edge of the main sail and the
forward stay edge of the jib would be the leading edges, so I don't
follow that if the wind is from abaft starboard, why you would want
the boom out to starboard.

Brian W<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

On 21 Nov 2004 12:18:14 -0800, sheepshaggerx RemoveThis @yahoo.co.uk (Love a
Sheep) wrote:

 >I am learning to sail and have a few questions. I understand that the
 >sails can act either as an airofoil (lile an aircraft wing) or like a
 >parachute where the wind simply blows the sail directly. My question
 >is this. If the wind is ahead of the beam ie we are sailing windward
 >then I expect that the airofoil principle must always hold there
 >otherwise we would be sailing backwards!

True
 >
 >However, if the wind is aft of the beam on say the starboard side then
 >surely we have a choice where to set the sails ie they can be on the
 >starboard side (ie the boom is pointing to the starboard side) where
 >they act as an airofoil or on the port side where they act as a
 >'parachute' - is this right or am I missing something. If so which is
 >best?

No. If the wind is from starboard, and abaft the beam, the sails will
not normally stay out to starboard, as the sheets are rigged to pull
the boom (and jib) into the boat.

It is possible with the wind very nearly dead astern to have the main
and jib on opposite sides - this usually works best with the wind
slightly to the same side as the boom. This is called "sailing by the
lee", and will lead to an accidental jibe if you let the wind get too
far to the same side as the boom (then you will find out why it is
called a boom )


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : <a style='text-decoration: underline;' href="http://vancouver-webpages.com/nnq" target="_blank">http://vancouver-webpages.com/nnq</a>
GPS and NMEA info: <a style='text-decoration: underline;' href="http://vancouver-webpages.com/peter" target="_blank">http://vancouver-webpages.com/peter</a>
Vancouver Power Squadron: <a style='text-decoration: underline;' href="http://vancouver.powersquadron.ca" target="_blank">http://vancouver.powersquadron.ca</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

"Peter Bennett" <peterbb DeleteThis @somewhere.invalid> wrote in message
news:t4c2q09jt6bsc9momnmqok9nnaip0cal6u@news.supernews.com...
 > On 21 Nov 2004 12:18:14 -0800, sheepshaggerx DeleteThis @yahoo.co.uk (Love a
 > Sheep) wrote:
 >
  >>I am learning to sail and have a few questions. I understand that the
  >>sails can act either as an airofoil (lile an aircraft wing) or like a
  >>parachute where the wind simply blows the sail directly. My question
  >>is this. If the wind is ahead of the beam ie we are sailing windward
  >>then I expect that the airofoil principle must always hold there
  >>otherwise we would be sailing backwards!
 >
 > True
  >>
  >>However, if the wind is aft of the beam on say the starboard side then
  >>surely we have a choice where to set the sails ie they can be on the
  >>starboard side (ie the boom is pointing to the starboard side) where
  >>they act as an airofoil or on the port side where they act as a
  >>'parachute' - is this right or am I missing something. If so which is
  >>best?
 >
 > No. If the wind is from starboard, and abaft the beam, the sails will
 > not normally stay out to starboard, as the sheets are rigged to pull
 > the boom (and jib) into the boat.
 >
 > It is possible with the wind very nearly dead astern to have the main
 > and jib on opposite sides - this usually works best with the wind
 > slightly to the same side as the boom. This is called "sailing by the
 > lee", and will lead to an accidental jibe if you let the wind get too
 > far to the same side as the boom (then you will find out why it is
 > called a boom )

For either the slow, stupid, or stunned, it's called the boom boom.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

Love a Sheep (sheepshaggerx@yahoo.co.uk) writes:

 > However, if the wind is aft of the beam on say the starboard side then
 > surely we have a choice where to set the sails ie they can be on the
 > starboard side (ie the boom is pointing to the starboard side) where
 > they act as an airofoil or on the port side where they act as a
 > 'parachute' - is this right or am I missing something. If so which is
 > best?

When a boom gets much forward of 90 degrees to the centreline it's hard
to pull back in from behind, reducing your ability to control the sail.

I have small boomless sails on my tiny boats which I can let forward all
the way and rotate them right around the mast. I often let the sail go
forward of the mast on a run in the manner you suggest so it's partially
acting as an airfoil. The sail is much more stable in that position. Sails
are least stable when running downwind. Spinnaker sails work much the same
as my rotating sails when let out forward.

Even in the standard upwind airfoil position only 2/3 of the power of a
sail is the airfoil vacuum on the front of the sail. There is still 1/3 of
the power from the "parachute" pressure on the back of the sail. It's
never one or the other but always a combination of both. Even on a dead
run air is pushing around the edges of the sail making a vacuum on the
front side. (Actually I imagine a true parachute has a vacuum on the upper
surface caused by the air from below passing over the curved surface.
Modern parachutists use an airfoil parachute which glides.)

There are some sails like the crab claw sail that aren't an airfoil. The
crab claw works like a kite. The air passing the edges of the sail makes
powerful vortecies which create the vacuum on the front side of the sail.
Crab claw sails produce the most power per squate foot of any type of sail
I'm aware of. Unfortunately they're not as easy to handle as a sail with
its front edge attached to a vertical mast.

On my website you can see photos of my rotating sails and my of crab
claw sail which lifts over the top of a short mast for easier handling.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: <a style='text-decoration: underline;' href="http://www.ncf.ca/~ag384/top.htm" target="_blank">www.ncf.ca/~ag384/top.htm</a>
warning: non-FreeNet email must have "notspam" in subject or it's returned<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

On 21 Nov 2004 12:18:14 -0800, sheepshaggerx.TakeThisOut@yahoo.co.uk (Love a
Sheep) wrote:

 >I am learning to sail and have a few questions. I understand that the
 >sails can act either as an airofoil (lile an aircraft wing) or like a
 >parachute where the wind simply blows the sail directly. My question
 >is this. If the wind is ahead of the beam ie we are sailing windward
 >then I expect that the airofoil principle must always hold there
 >otherwise we would be sailing backwards!
 >
 >However, if the wind is aft of the beam on say the starboard side then
 >surely we have a choice where to set the sails ie they can be on the
 >starboard side (ie the boom is pointing to the starboard side) where
 >they act as an airofoil or on the port side where they act as a
 >'parachute' - is this right or am I missing something. If so which is
 >best?
 >
You are right. But it depends on the particular boat where exactly the
optimum switchover from drawing to stalled takes place.

If you have shrouds, the decision may be made by how much chafe you
are willing to tolerate between spreaders and main. With an unstayed
mast you have more freedom to experiment.



Rodney Myrvaagnes NYC

Let's Put the XXX back in Xmas<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

Using the sail's trailing edge as a leading edge is problematic.
They will not be efficient this way - tantamount to running an
airplane wing backwards.

Letting them out on the port side however would work provided
you could let them out that far without fouling the rigging.

CN


"Love a Sheep" <sheepshaggerx DeleteThis @yahoo.co.uk> wrote in message news:264c4ea4.0411211218.1ff34ddb@posting.google.com...
 > I am learning to sail and have a few questions. I understand that the
 > sails can act either as an airofoil (lile an aircraft wing) or like a
 > parachute where the wind simply blows the sail directly. My question
 > is this. If the wind is ahead of the beam ie we are sailing windward
 > then I expect that the airofoil principle must always hold there
 > otherwise we would be sailing backwards!
 >
 > However, if the wind is aft of the beam on say the starboard side then
 > surely we have a choice where to set the sails ie they can be on the
 > starboard side (ie the boom is pointing to the starboard side) where
 > they act as an airofoil or on the port side where they act as a
 > 'parachute' - is this right or am I missing something. If so which is
 > best?
 >
 > Thanks<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

On Sun, 21 Nov 2004 12:18:14 -0800, Love a Sheep wrote:

 > I am learning to sail and have a few questions. I understand that the
 > sails can act either as an airofoil (lile an aircraft wing) or like a
 > parachute where the wind simply blows the sail directly. My question
 > is this. If the wind is ahead of the beam ie we are sailing windward
 > then I expect that the airofoil principle must always hold there
 > otherwise we would be sailing backwards!
 >
 > However, if the wind is aft of the beam on say the starboard side then
 > surely we have a choice where to set the sails ie they can be on the
 > starboard side (ie the boom is pointing to the starboard side) where
 > they act as an airofoil or on the port side where they act as a
 > 'parachute' - is this right or am I missing something. If so which is
 > best?
 >
 > Thanks

You've already got a lot of good answers. I'll just point out one more
thing which is that the two sails on a boat interact. That is, even when
the wind is aft of abeam, the wind flowing over the main may be dead abeam
or so, because the jib or spinnaker changes the direction of flow.

--Mac<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

sheepshaggerx RemoveThis @yahoo.co.uk (Love a Sheep) wrote in message news:<264c4ea4.0411211218.1ff34ddb RemoveThis @posting.google.com>...
 > I am learning to sail and have a few questions. I understand that the
 > sails can act either as an airofoil (lile an aircraft wing) or like a
 > parachute where the wind simply blows the sail directly. My question
 > is this. If the wind is ahead of the beam ie we are sailing windward
 > then I expect that the airofoil principle must always hold there
 > otherwise we would be sailing backwards!
 >
 > However, if the wind is aft of the beam on say the starboard side then
 > surely we have a choice where to set the sails ie they can be on the
 > starboard side (ie the boom is pointing to the starboard side) where
 > they act as an airofoil or on the port side where they act as a
 > 'parachute' - is this right or am I missing something. If so which is
 > best?
 >
 > Thanks
Once the wind if aft of the beam the generally accepted rule if to
have the boom at right angles to the wind. Likewise when you pole out
the headsail.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

sheepshaggerx RemoveThis @yahoo.co.uk (Love a Sheep) wrote in message news:<264c4ea4.0411211218.1ff34ddb RemoveThis @posting.google.com>...
 > I am learning to sail and have a few questions. I understand that the
 > sails can act either as an airofoil (lile an aircraft wing) or like a
 > parachute where the wind simply blows the sail directly. My question
 > is this. If the wind is ahead of the beam ie we are sailing windward
 > then I expect that the airofoil principle must always hold there
 > otherwise we would be sailing backwards!
 >
 > However, if the wind is aft of the beam on say the starboard side then
 > surely we have a choice where to set the sails ie they can be on the
 > starboard side (ie the boom is pointing to the starboard side) where
 > they act as an airofoil or on the port side where they act as a
 > 'parachute' - is this right or am I missing something. If so which is
 > best?
 >
 > Thanks

You can't really put both of your sails to what in your description
would be the windward side of the boat...well, not effectively at
least. here's why....

Unless you're sailing dead downwind (wing and wing, or by the lee, as
mentioned - boom toward the VERY slight widward side, also as
mentioned) you'll notice that no matter how far out you let your sails
when on an actual port or starboard tack, you're always going to have
the airfoil effect, not a parachute effect. Watch your telltails,
you'll see the wind moving across the sails, leading edge to trailng
edge. In your case, if the wind was from starboard, even fairly
significantly abaft the beam, you would still sail on starboard tack,
sails trimmed out to port. Once this becomes impossibly, it's either
time to jibe, or go wing and wing.

To relate this to a plane, think about the apparent wind when they
slow down to land and they 'set' the flaps to create much more 'belly'
in the wing to maintain that lift as the wind direction changes
(remember, apparent wind...of course, they're still going forward,
but the plane wants to fall, so the wind direction is now coming from
further under the wing, less in front of it, so they have to adjust,
just like you do) But there's no way a wing will act as a parachute on
a plane, it's still an airfoil. Same thing you're doing with your
sails. The difference is in the fact that a plane can also adjust it's
apparent wind direction by adjusting its speed. But the adjustments
are based on the same principle. If the plane went too slow, it would
fall of course, luckily, we don't have to worry about that, and when
the wind is directly behind us (i.e. the minimal amount of apparent
wind) - we CAN use the parachute effect. but it's only in that
scenario.

how's that for a long drawn out explanation! Sorry for the verbose
detail...hope it made even a bit of sense!

P.S. And yes, be careful sailing downwind wing and wing...accidental
jibes are not your friend. if you're going to do it for long, pole
out, and rig preventers, especially in rolly seas.

Good luck!

Capt. Rob Welling
Sarasota, FL<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

On Mon, 22 Nov 2004 04:02:33 GMT, Mac <foo RemoveThis @bar.net> wrote:

 >On Sun, 21 Nov 2004 12:18:14 -0800, Love a Sheep wrote:
 >
  >> I am learning to sail and have a few questions. I understand that the
  >> sails can act either as an airofoil (lile an aircraft wing) or like a
  >> parachute where the wind simply blows the sail directly. My question
  >> is this. If the wind is ahead of the beam ie we are sailing windward
  >> then I expect that the airofoil principle must always hold there
  >> otherwise we would be sailing backwards!
  >>
  >> However, if the wind is aft of the beam on say the starboard side then
  >> surely we have a choice where to set the sails ie they can be on the
  >> starboard side (ie the boom is pointing to the starboard side) where
  >> they act as an airofoil or on the port side where they act as a
  >> 'parachute' - is this right or am I missing something. If so which is
  >> best?
  >>
I misread your question before my previous answer, which therefore
made no sense. I thought you were asking about the transition between
drawing and stalling. The boom would be to port in either case with
the wind on starboard.

As the wind goes aft, the boom must be let out farther to maintain
flow. The mast is the leading edge.

When the wind is really aft, you would square the sail to the wind,
letting it stall. Then the drag of the sail is pushing the boat.

If you understand this so far, the real question becomes "Is there a
wind angle where the boat will go faster stalled than drawing, even
without the boom or sail hitting the rigging?

That is the question I was answering before, and it is not what you
actually asked.




Rodney Myrvaagnes J36 Gjo/a


Does one child rape really change Strom Thurmond's lifetime record?
For better or worse?<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

On Sun, 21 Nov 2004 16:30:46 -0800, "Jonathan Ganz"
<nospam.RemoveThis@noo231o1oospam.com> wrote:

 >
 >For either the slow, stupid, or stunned, it's called the boom boom.

We had a regatta in my club in 2001 during which a fellow was killed
via "boom boom". A storm front went through creating 50 knot winds
that...unusually...stayed at 30-35 knots most of the day even as the
sun came out. During the races, a poor bastard got clipped in the
head...hard...during a crash jib (no preventers or concept of "duck",
I assume). He failed to fall down and got smashed on the opposite side
of the head a couple of seconds later.

They pulled the plug on him after a week in a flatline coma.

Even though I recall the boat was a C&C 29, the motion was so fast and
hard that even that boat's 10 foot boom had enough velocity to crunch
a skull.

So use preventers and watch sea-state roll in downwind situations.

R.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

Just ignore crapton.

That sounds rough... Sounds like a combination of bad judgement on the part
of the skipper and the guy who got hit. We typically sail in 25+ kts, and
rarely use a preventer unless we're going to have a long downwind run. We
don't race though.

--
"j" ganz @@
<a style='text-decoration: underline;' href="http://www.sailnow.com" target="_blank">www.sailnow.com</a>

"rhys" <rhys DeleteThis @nospam.com> wrote in message
news:qif4q0d5hm17om1uqf83h5qu339jrchvbc@4ax.com...
 > On Sun, 21 Nov 2004 16:30:46 -0800, "Jonathan Ganz"
 > <nospam DeleteThis @noo231o1oospam.com> wrote:
 >
  >>
  >>For either the slow, stupid, or stunned, it's called the boom boom.
 >
 > We had a regatta in my club in 2001 during which a fellow was killed
 > via "boom boom". A storm front went through creating 50 knot winds
 > that...unusually...stayed at 30-35 knots most of the day even as the
 > sun came out. During the races, a poor bastard got clipped in the
 > head...hard...during a crash jib (no preventers or concept of "duck",
 > I assume). He failed to fall down and got smashed on the opposite side
 > of the head a couple of seconds later.
 >
 > They pulled the plug on him after a week in a flatline coma.
 >
 > Even though I recall the boat was a C&C 29, the motion was so fast and
 > hard that even that boat's 10 foot boom had enough velocity to crunch
 > a skull.
 >
 > So use preventers and watch sea-state roll in downwind situations.
 >
 > R.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question 

Poor fellow! The man lost his life primarily because
of poor design by the naval architect.

Those C&Cs are a death trap in more than one way it seems.

But, to design a cruising boat with a boom so low that it
can smack you up side the head is criminal. I should think
a nice little lawsuit would straighten out C&C and the
negligent designer.

You won't find a Wm. Tripp Jr. designed cruiser with such
flaws.

CN



"rhys" <rhys DeleteThis @nospam.com> wrote in message news:qif4q0d5hm17om1uqf83h5qu339jrchvbc@4ax.com...
 > On Sun, 21 Nov 2004 16:30:46 -0800, "Jonathan Ganz"
 > <nospam DeleteThis @noo231o1oospam.com> wrote:
 >
  > >
  > >For either the slow, stupid, or stunned, it's called the boom boom.
 >
 > We had a regatta in my club in 2001 during which a fellow was killed
 > via "boom boom". A storm front went through creating 50 knot winds
 > that...unusually...stayed at 30-35 knots most of the day even as the
 > sun came out. During the races, a poor bastard got clipped in the
 > head...hard...during a crash jib (no preventers or concept of "duck",
 > I assume). He failed to fall down and got smashed on the opposite side
 > of the head a couple of seconds later.
 >
 > They pulled the plug on him after a week in a flatline coma.
 >
 > Even though I recall the boat was a C&C 29, the motion was so fast and
 > hard that even that boat's 10 foot boom had enough velocity to crunch
 > a skull.
 >
 > So use preventers and watch sea-state roll in downwind situations.
 >
 > R.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Sailing Newbie Question