Seamanship Question #24
 

Gary wrote:
Thinking further about this question, why would the mast come down if
the main parted?

Because of the compression load from the spinnaker.

... Presumably, when the main is eased all the way out
when running, it doesn't provide any support to the mast.

Possible, but I doubt it on these boats. Most of the A-sail boats I've
been on, or seen go by, never eased the main out more than about a foot
past the gun'l, except in light air.


... The sail and
mainsheet will only provide support when close-hauled. It is the
shrouds and aft swept spreaders that keep the mast up.

Another issue is that this particular boat (and a number of other
sportboats) have a frac rig & a mast head spinnaker. The top section of
the mast is unsupported except by the main leach, which might not matter
under many conditions... but in 30 knot winds?

... I don't think
the rig would come down with no main up. If it did, I wouldn't have one.


I can see your point, but if you wanna go fast, you have to make
compromises.

Fresh Breezes- Doug King

Seamanship Question #24
 

DSK wrote:
Gary wrote:

Thinking further about this question, why would the mast come down if
the main parted?


Because of the compression load from the spinnaker.
Compression load is not relieved by having the main up or by having a
backstay.

... Presumably, when the main is eased all the way out when running,
it doesn't provide any support to the mast.


Possible, but I doubt it on these boats. Most of the A-sail boats I've
been on, or seen go by, never eased the main out more than about a foot
past the gun'l, except in light air.
No race boat, sailed by some one who new what they were doing, would run
with the kite up and main sheeted in to the gunnel. It would cause the
boat to round up badly. You must have been much higher on the wind if
the main was sheeted in.


... The sail and mainsheet will only provide support when
close-hauled. It is the shrouds and aft swept spreaders that keep the
mast up.


Another issue is that this particular boat (and a number of other
sportboats) have a frac rig & a mast head spinnaker. The top section of
the mast is unsupported except by the main leach, which might not matter
under many conditions... but in 30 knot winds?
I was racing in the Van-Isle 360 (http://www.vanisle360.com/) when
Casseopia (a turbo'd Davidson 70) lost the top of her rig like that.
Her backstay broke. I think the top section needs support and as
discussed above, it doesn't get it from the main leech.

... I don't think the rig would come down with no main up. If it did,
I wouldn't have one.


I can see your point, but if you wanna go fast, you have to make
compromises.
That is just stupid.

Fresh Breezes- Doug King

Seamanship Question #24
 

"Gary" wrote in message
news:bXbcf.448995$tl2.280282@pd7tw3no...
DSK wrote:
Gary wrote:

Thinking further about this question, why would the mast come down if
the main parted?


Because of the compression load from the spinnaker.
Compression load is not relieved by having the main up or by having a
backstay.

... Presumably, when the main is eased all the way out when running, it
doesn't provide any support to the mast.


Possible, but I doubt it on these boats. Most of the A-sail boats I've
been on, or seen go by, never eased the main out more than about a foot
past the gun'l, except in light air.
No race boat, sailed by some one who new what they were doing, would run
with the kite up and main sheeted in to the gunnel. It would cause the
boat to round up badly. You must have been much higher on the wind if the
main was sheeted in.


... The sail and mainsheet will only provide support when close-hauled.
It is the shrouds and aft swept spreaders that keep the mast up.


Another issue is that this particular boat (and a number of other
sportboats) have a frac rig & a mast head spinnaker. The top section of
the mast is unsupported except by the main leach, which might not matter
under many conditions... but in 30 knot winds?
I was racing in the Van-Isle 360 (http://www.vanisle360.com/) when
Casseopia (a turbo'd Davidson 70) lost the top of her rig like that. Her
backstay broke. I think the top section needs support and as discussed
above, it doesn't get it from the main leech.

Hey, why dincha post up this link?

http://www.vanisle360.com/2005legs/video.php

Amazing, they still managed a 2nd after the mob.

John Cairns

... I don't think the rig would come down with no main up. If it did, I
wouldn't have one.


I can see your point, but if you wanna go fast, you have to make
compromises.
That is just stupid.

Fresh Breezes- Doug King

Seamanship Question #24
 

"Gary" wrote in message
news:bXbcf.448995$tl2.280282@pd7tw3no...

DSK wrote:

Gary wrote:


Thinking further about this question, why would the mast come down if
the main parted?


Because of the compression load from the spinnaker.

Compression load is not relieved by having the main up or by having a
backstay.

... Presumably, when the main is eased all the way out when running, it
doesn't provide any support to the mast.


Possible, but I doubt it on these boats. Most of the A-sail boats I've
been on, or seen go by, never eased the main out more than about a foot
past the gun'l, except in light air.

No race boat, sailed by some one who new what they were doing, would run
with the kite up and main sheeted in to the gunnel.

Really?

What about these guys?

http://www.blewbayou.com/images/Big_Blue_pic2.jpg
http://www.yachtsoft.com/Eagle.HTM

Look at some pics of Melges 24s racing.

.... It would cause the
boat to round up badly. You must have been much higher on the wind if the
main was sheeted in.


The apparent wind shifts far forward on these boats. It has to, for the
A-sail work well. And also, the draft off the leach of the spinnaker is
shifted even further.

Whatever.




I was racing in the Van-Isle 360 (http://www.vanisle360.com/) when
Casseopia (a turbo'd Davidson 70) lost the top of her rig like that. Her
backstay broke. I think the top section needs support and as discussed
above, it doesn't get it from the main leech.


As discussed above, it surely does. Where do you think the tension on
the vang ends up?

Anyway, the issue is not "support" for the mast top, since the opposing
load on the main only adds to the compression. But it keeps it in column.


John Cairns wrote:
Hey, why dincha post up this link?

http://www.vanisle360.com/2005legs/video.php

Amazing, they still managed a 2nd after the mob.

Dang, that's cool. Thanks for the link

... I don't think the rig would come down with no main up. If it did, I
wouldn't have one.


I can see your point, but if you wanna go fast, you have to make
compromises.

That is just stupid.

Maybe so, but a lot of people buy these kinds of boats. FWIW I think
they're a lot of fun. But then I'm not planning on buying one either.

Fresh Breezes- Doug King

Seamanship Question #24
 

"DSK" wrote

Bart Senior wrote:
Good point. Putting a reef in would be a big help.
Tensioning the clue reef line, would help support the mast.

Agreed, and I didn't think of it, but I hope I would if it was really
happening... when you look up at the sail, you see these things and might
get the idea.

I'm sure you wound. It happened to me once on a J-24. I
reached up and clapped on the reef line and put all my weight
on it. It tensioned up nicely. We dropped the main rather quickly
after that.

Seamanship Question #24
 

For one thing, with swept back spreaders you
can't let the main all the way out. The Cheetah
is also faster downwind on a broad reach than
a run. Tacking downwind is the norm. So the
main would probably not be out all the way. Also
forward pressure of the sail is conteracted by
mainsheet tension.

"Gary" wrote

Thinking further about this question, why would the mast come down if the
main parted? Presumably, when the main is eased all the way out when
running, it doesn't provide any support to the mast. The sail and
mainsheet will only provide support when close-hauled. It is the shrouds
and aft swept spreaders that keep the mast up. I don't think the rig
would come down with no main up. If it did, I wouldn't have one.

Gary

Seamanship Question #24
 

DSK wrote:

Thinking further about this question, why would the mast come down
if the main parted?

Because of the compression load from the spinnaker.

Compression load is not relieved by having the main up or by having a
backstay.

... Presumably, when the main is eased all the way out when
running, it doesn't provide any support to the mast.

Possible, but I doubt it on these boats. Most of the A-sail boats
I've been on, or seen go by, never eased the main out more than
about a foot past the gun'l, except in light air.

No race boat, sailed by some one who new what they were doing, would
run with the kite up and main sheeted in to the gunnel.


Really?

What about these guys?

http://www.blewbayou.com/images/Big_Blue_pic2.jpg
http://www.yachtsoft.com/Eagle.HTM

Look at some pics of Melges 24s racing.
If you look at those boats closely you will see that they are not
running. On the Big Blue page it's hard to see but on the Eagle page
the left pictureb is setting up to blow the kite rounding the mark, he
is not running. The lower picture is close reaching, look at his flag.
Finally, all these guy have backstays.

.... It would cause the boat to round up badly. You must have been
much higher on the wind if the
main was sheeted in.


The apparent wind shifts far forward on these boats. It has to, for the
A-sail work well. And also, the draft off the leach of the spinnaker is
shifted even further.
When the apparent wind comes forward, you are no longer running.

Whatever.




I was racing in the Van-Isle 360 (http://www.vanisle360.com/) when
Casseopia (a turbo'd Davidson 70) lost the top of her rig like that.
Her backstay broke. I think the top section needs support and as
discussed above, it doesn't get it from the main leech.



As discussed above, it surely does. Where do you think the tension on
the vang ends up?
The vang certainly flattens the main when the sheets are eased and no
doubt provides some support for the mast but doesn't hold it up in 30
knots of wind. It is the design of the entire rig that keeps it up.

Anyway, the issue is not "support" for the mast top, since the opposing
load on the main only adds to the compression. But it keeps it in column.


John Cairns wrote:

Hey, why dincha post up this link?

http://www.vanisle360.com/2005legs/video.php

Amazing, they still managed a 2nd after the mob.


Dang, that's cool. Thanks for the link

... I don't think the rig would come down with no main up. If it
did, I wouldn't have one.


I can see your point, but if you wanna go fast, you have to make
compromises.


That is just stupid.


Maybe so, but a lot of people buy these kinds of boats. FWIW I think
they're a lot of fun. But then I'm not planning on buying one either.

Fresh Breezes- Doug King