My old visqueen sails for the MiniCups finally fell apart so I have
bought some white polytarp material to make new ones. The old
directions said nothing about shaping the sails but the polytarp sail
manual discusses it. However, they also make reference to lateen sails
being self shaping. So, what to do, cut them with a curvature (what I
plan to do) or make straight cuts?
Next, how much does stitching lengthen the life of the sails?

) writes:

However, they also make reference to lateen sails
being self shaping.

Wind tunnel test have shown lateen sails to be the least efficient.
The lower the angle of the top spar the less efficient the sail.
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wrote:

My old visqueen sails for the MiniCups finally fell apart so I have
bought some white polytarp material to make new ones. The old
directions said nothing about shaping the sails but the polytarp sail
manual discusses it. However, they also make reference to lateen sails
being self shaping. So, what to do, cut them with a curvature (what I
plan to do) or make straight cuts?
Next, how much does stitching lengthen the life of the sails?

Yes - lateen sails are flat - no 'body' sewn into them

paul oman
progressive epoxy polymers

Interesting theory. When I was racing my Sunfish, I was able to go to
windward much better after the sail developed some body. The drill with a
new sail was to run it thru the washing machine some six or eight times to
soften it. Some years later the official Sunfish lateen was given more body
in the sail loft.

Roger

http://home.earthlink.net/~derbyrm
"Paul Oman" wrote in message
...
wrote:

My old visqueen sails for the MiniCups finally fell apart so I have
bought some white polytarp material to make new ones. The old
directions said nothing about shaping the sails but the polytarp sail
manual discusses it. However, they also make reference to lateen sails
being self shaping. So, what to do, cut them with a curvature (what I
plan to do) or make straight cuts?
Next, how much does stitching lengthen the life of the sails?

Yes - lateen sails are flat - no 'body' sewn into them

paul oman
progressive epoxy polymers

On 16 Apr 2005 20:03:14 -0700, wrote:

My old visqueen sails for the MiniCups finally fell apart so I have
bought some white polytarp material to make new ones. The old
directions said nothing about shaping the sails but the polytarp sail
manual discusses it. However, they also make reference to lateen sails
being self shaping. So, what to do, cut them with a curvature (what I
plan to do) or make straight cuts?
Next, how much does stitching lengthen the life of the sails?

If you are really interested in extending the life of your sails, why
not try sailcloth?


Rodney Myrvaagnes Opinionated old geezer J36 Gjøa


I wonder if the tourists following the wine-tasting
circuit in 'Sideways' start off by doing the NY Times
crossword in ink as they drive up I-5?

wrote:
My old visqueen sails for the MiniCups finally fell apart

After how many hours of use? In what average strength wind?

... so I have
bought some white polytarp material to make new ones. The old
directions said nothing about shaping the sails but the polytarp sail
manual discusses it.

By broadseaming of luff curvature? You might try putting a little shape
in one seam and a few inches of luff curvature... the right curve will
make a noticable difference in how the boat sails.

... However, they also make reference to lateen sails
being self shaping. So, what to do, cut them with a curvature (what I
plan to do) or make straight cuts?

If a lateen rig has any "self-shaping" properties then it would be the
opposite shape of what is desired. The leach tension would tend to bend
the gaff or lateen upper spar so as to pull cloth out of the middle of
the sail... if the sail were cut flat, then this inverted shape would be
horrible. If the sail were cut with the proper shaping for
light/moderate wind (ie with no bend in the gaff) then the
"self-shaping" could become beneficial; ie flattening the sail &
depowering it when that would be desirable.


Next, how much does stitching lengthen the life of the sails?


Not at all, but it could shorten it.


Rodney Myrvaagnes wrote:
If you are really interested in extending the life of your sails, why
not try sailcloth?


Oh man, you just don't understand creative thinking & original problem
solving! It is much better to have to make new sails every couple of
months, that way you can recycle the material faster and spend far less
money in the short run, plus spend a lot of time (which of course only
equates to money if you are a capitalist brain-dead bourgeoisie)
communing with the inner spirit of your wind-capturing device...

DSK

DSK ) writes:

Next, how much does stitching lengthen the life of the sails?


Not at all, but it could shorten it.

shouldn't someone warn the professional sail lofts about this?

the only problem with both taping and sewing seams is the glue gums up the
needle on the sewing machine. I cello-taped the seams of a nylon sail to hold
them togeher while I shoved them through a sewing machine and had quite a
problem with cleaning the needle. Last year I sewed a Tyvek sail without using
any tape and it looks good. I haven't tried a heat sealed polytarp sail.
Photos of the nylon sail under "Dogskiff" and Tyvek sail under "Tyvek
Sail", both under "Boats" on my website (see below).
--
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William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned

Next, how much does stitching lengthen the life of the sails?

Not at all, but it could shorten it.


William R. Watt wrote:
shouldn't someone warn the professional sail lofts about this?


I think most of the good ones already know.


the only problem with both taping and sewing seams is the glue gums up the
needle on the sewing machine.

Why sew them if they're glued? Many sail lofts are now producing glued
seam sails... I have a ~200 Sq Ft spinnaker that I've flown in 20+ knot
winds, plenty strong.

Fresh Breezes- Doug King

Being a pathological experimenter (There ought to be a 12 step program
for people who cannot follow directions), the polytarp allows me to
economically stay in touch with my inner geekiness.

On Sun, 17 Apr 2005 23:35:33 -0400, DSK wrote:

wrote:
My old visqueen sails for the MiniCups finally fell apart

After how many hours of use? In what average strength wind?

... so I have
bought some white polytarp material to make new ones. The old
directions said nothing about shaping the sails but the polytarp sail
manual discusses it.

By broadseaming of luff curvature? You might try putting a little shape
in one seam and a few inches of luff curvature... the right curve will
make a noticable difference in how the boat sails.

... However, they also make reference to lateen sails
being self shaping. So, what to do, cut them with a curvature (what I
plan to do) or make straight cuts?

If a lateen rig has any "self-shaping" properties then it would be the
opposite shape of what is desired. The leach tension would tend to bend
the gaff or lateen upper spar so as to pull cloth out of the middle of
the sail... if the sail were cut flat, then this inverted shape would be
horrible. If the sail were cut with the proper shaping for
light/moderate wind (ie with no bend in the gaff) then the
"self-shaping" could become beneficial; ie flattening the sail &
depowering it when that would be desirable.


Next, how much does stitching lengthen the life of the sails?


Not at all, but it could shorten it.


Rodney Myrvaagnes wrote:
If you are really interested in extending the life of your sails, why
not try sailcloth?


Oh man, you just don't understand creative thinking & original problem
solving! It is much better to have to make new sails every couple of
months, that way you can recycle the material faster and spend far less
money in the short run, plus spend a lot of time (which of course only
equates to money if you are a capitalist brain-dead bourgeoisie)
communing with the inner spirit of your wind-capturing device...

DSK

OK, I understand. Suggestion withdrawn. :-)




Rodney Myrvaagnes Opionated old geezer

Faith-based economics: It's deja voodoo all over again