My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience, although he
has a fair amount more than I. We were discussing running up a spinnaker at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to our our
different conclusions as to why it would not be. I felt that there would be
no point to put it up, as it would just get blown into the rigging and not
really tell us anything and possibly get torn. He was of the opinion that
somehow the spinnaker could push the boat to one side, fill and turn the
boat around. Initially he said it would go right upwind of the mooring,
then reduced his claim to say that it would turn around at the point where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under no
combination of sail at a mooring could the boat turn around so that the aft
was upwind. I am of the opinion that you could get the boat to swing to one
side or the other a bit by backing the jib, but you could still never turn
the boat around.

I would gratefully accept as many informed opinions on this from a sailing
or physics point of view.

Fair winds,
Miles

Hi Miles

Anchor the boat by the stern and you will be able to set the spinnaker just
fine.

--
Regards - Terry Hollis, Auckland, New Zealand

replace "nospam" with "terry.hollis" to reply

"Blorgad" wrote in message
...
My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience, although
he
has a fair amount more than I. We were discussing running up a spinnaker
at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to our
our
different conclusions as to why it would not be. I felt that there would
be
no point to put it up, as it would just get blown into the rigging and not
really tell us anything and possibly get torn. He was of the opinion that
somehow the spinnaker could push the boat to one side, fill and turn the
boat around. Initially he said it would go right upwind of the mooring,
then reduced his claim to say that it would turn around at the point where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under no
combination of sail at a mooring could the boat turn around so that the
aft
was upwind. I am of the opinion that you could get the boat to swing to
one
side or the other a bit by backing the jib, but you could still never turn
the boat around.

I would gratefully accept as many informed opinions on this from a sailing
or physics point of view.

Fair winds,
Miles

A spinnaker flying forward of the bow is applying a load that could (in
theory) turn the boat around so it was lying with its stern pointing into
the wind. Imagine a vessel with some enormous fitting sited so far forward
of the mooring point that when the breeze blew it simply turned around so
that it was effectively downwind of the mooring.

But a boat and spinnaker in this configuration would be unstable, because
the load is being applied through sheets and braces (and a mast) that are
positioned well aft of the mooring point. The tiniest bit of force
off-centre would cause the load to be applied in a way that continued the
turning moment until the boat was either trying to sail the mooring out
sideways, or had the spinnaker wrapped around the forestay.

I think the way to answer the question is to imagine setting the spinnaker
with the boat moored by the stern, then imagine dragging the mooring line
towards the bow - how far can you get before the arrangement becomes
unstable?

We have hoisted the spinnaker while anchored by the stern. I have also
sailed off the mooring under spinnaker alone (after moving the mooring to
the stern) but my spinnaker is too expensive to put your question to a
practical test!
--

"Blorgad" wrote in message
...
My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience, although
he
has a fair amount more than I. We were discussing running up a spinnaker
at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to our
our
different conclusions as to why it would not be. I felt that there would
be
no point to put it up, as it would just get blown into the rigging and not
really tell us anything and possibly get torn. He was of the opinion that
somehow the spinnaker could push the boat to one side, fill and turn the
boat around. Initially he said it would go right upwind of the mooring,
then reduced his claim to say that it would turn around at the point where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under no
combination of sail at a mooring could the boat turn around so that the
aft
was upwind. I am of the opinion that you could get the boat to swing to
one
side or the other a bit by backing the jib, but you could still never turn
the boat around.

I would gratefully accept as many informed opinions on this from a sailing
or physics point of view.

Fair winds,
Miles

wrote...

Anchoring a boat by it's stern is generally considered a bad idea for good
reason.

For normal anchoring, that may well be true. However, for the stated
purpose (practice with the spinnaker at the mooring) it is not a bad idea at
all. There will be at least 2 crew on deck for the entire exercise, so they
can take care of any unforeseen problems.

No you wont sail forward of the mooring.

However,, When you want to hoist a kite while at the mooring. Just turn the
boat around and moor to the stern. Do it on a gentle day tho


DP
"Blorgad" wrote in message
...
My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience, although
he
has a fair amount more than I. We were discussing running up a spinnaker
at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to our
our
different conclusions as to why it would not be. I felt that there would
be
no point to put it up, as it would just get blown into the rigging and not
really tell us anything and possibly get torn. He was of the opinion that
somehow the spinnaker could push the boat to one side, fill and turn the
boat around. Initially he said it would go right upwind of the mooring,
then reduced his claim to say that it would turn around at the point where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under no
combination of sail at a mooring could the boat turn around so that the
aft
was upwind. I am of the opinion that you could get the boat to swing to
one
side or the other a bit by backing the jib, but you could still never turn
the boat around.

I would gratefully accept as many informed opinions on this from a sailing
or physics point of view.

Fair winds,
Miles

wrote...

The stated purpose is a poor idea for doing that in the first place. The
two
crew on deck that you stake so much faith in, are admittedly
inexperienced
sailors. There is no way to forsee what situations they are capable of
dealing
with. Meanwhile, they aren't really gonna learn much about spinnakers this
way
any how. The whole idea is a non-starter.

Not according to those who said they've done it successfully in the past!

Why have a sailboat if you only put the sails up at the mooring.

"d parker" wrote in message
...
No you wont sail forward of the mooring.

However,, When you want to hoist a kite while at the mooring. Just turn
the
boat around and moor to the stern. Do it on a gentle day tho


DP
"Blorgad" wrote in message
...
My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience,
although
he
has a fair amount more than I. We were discussing running up a
spinnaker
at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to our
our
different conclusions as to why it would not be. I felt that there
would
be
no point to put it up, as it would just get blown into the rigging and
not
really tell us anything and possibly get torn. He was of the opinion
that
somehow the spinnaker could push the boat to one side, fill and turn
the
boat around. Initially he said it would go right upwind of the mooring,
then reduced his claim to say that it would turn around at the point
where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under no
combination of sail at a mooring could the boat turn around so that the
aft
was upwind. I am of the opinion that you could get the boat to swing to
one
side or the other a bit by backing the jib, but you could still never
turn
the boat around.

I would gratefully accept as many informed opinions on this from a
sailing
or physics point of view.

Fair winds,
Miles

Using the mooring is a great way to get used to
gybing-setting-dropping-floating the kite. Particularly for noobs. Cos there
is only one thing happening at one time. They don't have to worry about the
main, helming, other boats etc.

Then once they understand it they can take that knowledge out on the water
and put it to good use.

DP
"Richard" wrote in message
t...
Why have a sailboat if you only put the sails up at the mooring.

"d parker" wrote in message
...
No you wont sail forward of the mooring.

However,, When you want to hoist a kite while at the mooring. Just turn
the
boat around and moor to the stern. Do it on a gentle day tho


DP
"Blorgad" wrote in message
...
My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience,
although
he
has a fair amount more than I. We were discussing running up a
spinnaker
at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to
our
our
different conclusions as to why it would not be. I felt that there
would
be
no point to put it up, as it would just get blown into the rigging and
not
really tell us anything and possibly get torn. He was of the opinion
that
somehow the spinnaker could push the boat to one side, fill and turn
the
boat around. Initially he said it would go right upwind of the
mooring,
then reduced his claim to say that it would turn around at the point
where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under
no
combination of sail at a mooring could the boat turn around so that
the
aft
was upwind. I am of the opinion that you could get the boat to swing
to
one
side or the other a bit by backing the jib, but you could still never
turn
the boat around.

I would gratefully accept as many informed opinions on this from a
sailing
or physics point of view.

Fair winds,
Miles

I'll agree, but with one small proviso - a lot of the skill in
gybing-setting-dropping-floating the kite is having the helmsman point the
boat in the right direction at each stage of the manoeuvre, and that can't
be learnt at anchor. Becoming familiar with the tasks involved is a good
start, but getting the procedure down pat requires coordination between
helmsman and crew that is only possible under weigh.

Finding conditions calm enough to actually set the spinnaker while anchored
is difficult. We usually introduce new sailors to spinnakers by going
through the motions with braces, sheets, pole etc, but no sail. You need one
extra person who pretends to be the clew. I have also done this under sail
with mainsail only, which is an interesting exercise for a crew that thinks
it already knows how to handle the spinnaker. We had one crew that decided
this practicing lark was beneath their dignity and weren't taking it
seriously. During the practice drop the person pretending to be the clew
decided to test whether the stopper knot had been tied in the sheet
properly. By timing carefully with the bowman releasing the tack, he
managed to pull the sheet out of its lead so that the virtual spinnaker was
streaming from the masthead with no brace and the sheet trailing in the
water! We refused to move on to the next exercise until they got it down. Of
course, the breeze strengthened at exactly that moment (it always does) and
the helmsman was jumping up and down screaming about the virtual
mudbank/cliff/oil tanker just a few boatlengths to leeward! We stopped them
when they were about to send someone up the mast, but they took the practice
a little more seriously after that.
--

"d parker" wrote in message
...

Using the mooring is a great way to get used to
gybing-setting-dropping-floating the kite. Particularly for noobs. Cos
there
is only one thing happening at one time. They don't have to worry about
the
main, helming, other boats etc.

Then once they understand it they can take that knowledge out on the water
and put it to good use.

You will end up tearing the chute.
Cant be done unless some unusual tide/wind condition.

You can moor your boat stern to the wind and put your spinaker up.

"Blorgad" wrote in message
...
My friend and I are having a disagreement regarding the behaviour of
sailboats on a mooring. We both have limited sailing experience, although
he
has a fair amount more than I. We were discussing running up a spinnaker
at
mooring in calm air, just to practice putting it up. We eventually
concluded that this wasn't practical, but the argument came in as to our
our
different conclusions as to why it would not be. I felt that there would
be
no point to put it up, as it would just get blown into the rigging and not
really tell us anything and possibly get torn. He was of the opinion that
somehow the spinnaker could push the boat to one side, fill and turn the
boat around. Initially he said it would go right upwind of the mooring,
then reduced his claim to say that it would turn around at the point where
it was attached to the line at the bow.

I am of the opinion that this is physically impossible and that under no
combination of sail at a mooring could the boat turn around so that the
aft
was upwind. I am of the opinion that you could get the boat to swing to
one
side or the other a bit by backing the jib, but you could still never turn
the boat around.

I would gratefully accept as many informed opinions on this from a sailing
or physics point of view.

Fair winds,
Miles