Help with tear in sail

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

See you local loft.

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

see below

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

There it is.

sergem · Joined: 24 Oct 2003 Posts: 246

very interesting, please continue, thank you!

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

I wanted to add that I purchase my sailcloth materials from Dimension Polyant, but they are a source for people in the trade and not for general consumers. Those materials might be available from a reputable repair loft.

USAM1 · Joined: 19 Sep 1994 Posts: 35

great stuff, keep it coming.

surfalex · Joined: 08 Aug 2008 Posts: 16

What a great post, I rip and tear alot of sails, this is realy going to help me getting my sails fixed " the right way "
Has anyony tried the Sailrite LSZ-1 zig zag sewing machine. ? Or any other good industrial machines that can feed a slippery sail and get you a even looking stitch.

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

Some machines can be fitted with a "puller" which is a powered roller which helps advance the cloth. My Bernina came with a puller but it always seemed to be getting in the way so I took it off. It worked fine on long seams but was a problem in tight areas or areas where there were irregularities in the surface, like clew grommets. You'll find it is best to practice on an old trash sail until you learn how to gently push or pull on the sail to help it feed.

lrrry · Joined: 26 Aug 2008 Posts: 10

Bob,

How long did it take you to do that repair?

And, any possibility of a quick lesson on just patching sails? Best materials to use, techniques....

lrrry · Joined: 26 Aug 2008 Posts: 10

Bob,

How long did it take you to do that repair?

And, any possibility of a quick lesson on just patching sails? Best materials to use, techniques....

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

It took about 4 hours to replace all 3 panels shown. I almost never just patch over a tear. Most small tears can be patched using "Sail Bandage" or "RV Awning Repair Tape". You can find them using a Google Search.

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

Bump! Back to the front of the pile just in case someone out there needed to do some repairs over the winter.

jingebritsen · Joined: 21 Aug 2002 Posts: 865

Do you copy the broad seam shaping as well? Looks tough to reconstruct that part. Positive down low and negative up top....

thombiz · Joined: 25 Jun 2007 Posts: 260 Location: Corpus Christi

That is a very good question. And I have to say, no, I do not copy the broad seaming unless it is and integral part of the construction like Ezzy's. First, let me say, I'm intimately familiar with sail construction and for the life of me, I have yet to fully understand this concept of broad seaming and seam shaping to the point I can completely replicate it. Mostly, I think it is advertising hype. With the exception of Ezzy, most manufacturers create a sail on a FLAT surface then apply the batten pockets to that flat surface sail body. A little bit of give and flex here and there from the batten pockets is inherent in the construction due to the use of sewing and sticky tape to put things together as opposed to an inflexible adhesive or welding. This little bit of flex, maybe .006" per seam under severe loading is supposed to give that bit of elasticity which is the magic in the sail. Ok, so lets say we get 10 seams to give that much which adds up to about .06". Really not much in the scheme of things, especially when that much stretching is achieved only at the most extreme possible loading of every seam. Picture a Sumo wrestler on a 5.0 in 40 mph winds. You get much more stretch and distortion in a sail by leaving high batten tension in a sail after each use, especially in hot weather. Now picture a sail with twist built into the design, like most sails. On a sail like that, the .06" of elasticity means almost nothing. I would think it is much less than material stretch over the body of the sail. Hence, my supposition that broadseam shaping is mostly advertising hype and plain ol' bullshit.

Ezzy is a bit different. Because of the way he creates batten pockets, he builds a certain amount of elasticity into the design and that elasticity over 10 seams is well in exces of .06". Just guessing, but I would think you might be able to get a give and take over the length of an Ezzy 6.0 sail of 3/8" or more as it goes thru load and unload cycles. Now that is broadseam shaping. Puting a new panel in an Ezzy is a matter of laying a new piece of matching scrim over the old piece to exactly duplicate the original shape and seaming, stitching it down and cutting out the old panel. The broadseam shaping is exactly duplicated.

And finally, there is the question of how far does a repair go to try to replicate what was original. Most people do not want to pay for all that extra time required to exactly replicate OEM seaming. They are happy if I can get it to 98% of what it was before the damage. I have to add, most damages to sails distort the OEM shape, stretching here and there at an uneven rate. It's tough enough just getting the sail back to that 98% of being like new shape. Add to that the panel distortion caused by extremely high batten tension used in some sails and just getting the shape to return to 98% of OEM is a major accomplishment.

Mostly, I think "seam shaping" is a buzzword du jour, like "transformational", "embedded", and "gravitas"

DanWeiss · Joined: 24 Jun 2008 Posts: 405 Location: Boston, MA

Bob: About your doubts whether seam shaping is inherent in the design. I'm sure you know that seam shaping is used because the sail panels themselves are flat. Seam shaping occurs when a curved edge of one panel is sewn to an edge of another panel having more or less curve than the first. Again, I know you know this is the definition.

Without seam shaping, any mast deflection to leeward would cause the entire sail to collapse except at the leech (assuming negative leech tension to start.) With subtle curves built into the sail, it can assume a shape that then can be supported through batten tension and skin tension caused, in part, by shaping.

I really don't think seam shaping is BS. What may cause some to think seam shaping doesn't exist in sails except when a seam runs diagonally across the chord of the sail is because most shaping seams on most sails are under the batten pockets, I think.

I do agree that exact replication of seam shaping offers a huge challenge when replacing an entire panel, for all the reasons you describe.

If it is of any interest, here are some links that help explain sail shaping from the perspective of a sail maker:

http://www.ehow.com/video_2358451_marking-broadseaming-sail.html

http://www.ehow.com/video_2358452_taping-broadseams-sail.html

Thanks again for your great posts!