Sewing Dacron sail tape

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Sewing Dacron sail tape

Postby KingsTransom » Fri Jul 08, 2016 12:43 pm

Hi all,
I have a few short tears in my original Daysailer main sail. I used Dacron sail tape on both sides, and now need to zig-zag stitch over the edges. I plan to use a machine, so my concern is that the needle and thread will drag adhesive along with it and gum up the works. I've considered spraying the needle periodically with silicon lube to prevent that. Has anyone done this? Should I also stitch near the ends of the tears to "lock" the tear, or does the patch take all the strain off the tear?

Two repairs are on the foot, so I wrapped the tape from about 1.5" up on the sail, down and around the foot, back up the other side. I'm concerned that the adhesive will curl the tape off that part while threading the sail in the boom slot. I can stitch the sail part, but there is no good way to stitch where the foot rope is - probably even by hand with a curved needle. Any better ideas?

Thanks,

Scott

BTW, I'm pretty sure Dacron sail tape is just surgical tape, so if anyone finds themselves in an emergency, there's a possible hack.
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Re: Sewing Dacron sail tape

Postby Solarwinds » Fri Jul 08, 2016 7:07 pm

There are a lot of internet postings on how to use tape and glue and/or just glue. Lots of references on just using 3M 5200. Take a look.
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Re: Sewing Dacron sail tape

Postby GreenLake » Fri Jul 08, 2016 7:55 pm

3M 5200 for sail repair?
~ green ~ lake ~ ~
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Re: Sewing Dacron sail tape

Postby TIM WEBB » Fri Jul 08, 2016 10:33 pm

If you are going to sew, your best bet is to go with non-adhesive materials. You are correct in that the adhesives can gum up a sewing machine faster than you can say oops. Adhesive-backed ripstop nylon tapes were banned years ago in the parachute industry, because the residue they leave behind almost always results in a larger, proper repair being needed later ...
Tim Webb
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(I used to be Her "staff", in the way dogs have owners and cats have staff, but alas no longer ... <pout>)
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Re: Sewing Dacron sail tape

Postby FloridaTom » Sat Jul 09, 2016 8:07 am

Hi -
Since you've already got the dac tape on both sides, you're kind of committed :wink:
If you just have a home machine, use a #16 needle and some all polyester button hole thread , or something strong like that.
Don't use nylon, even though it's strong - The sun will eat it quickly.
A sailmaker would use a bonded poly thread, probably "V-69" for that weight cloth, but I don't think you could use a needle big enough for it.

As far as the adhesive goes, I don't think you'll have a problem - If you do, spraying silicone on the needle will work fine.

Just sew the edges of the tape - Since the sail is taped both sides, I don't think the tear will spread - Not exactly textbook rip repair, but it'll work.
For a home machine, set for the widest zig-zag , and set the length so the stitch steps are kind of at right angles, and look "square" -
Does that make sense?
Sew the patch so that one side of the zig-zag "points" is close to the patch edges, maybe 1/32" - 1/16" in from the edge -
Back stitch a little at the start and end of your sewing.

For the bolt rope, use a zipper foot, and straight-stitch right next to the rope - Hopefully, it'll pull the tape in enough so the sail will still slide.
Again, not textbook , but I think you'll be OK .

The dac tape is a good thing to have for emergency repair - WAY better than the duct tape jobs I've seen -
We always charge extra when we get a duct taped sail in for repairs .
And PLEASE leave the 3M 5200 out of the equation, if you have any intent of ever getting the sail properly repaired, later

Tom
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Re: Sewing Dacron sail tape

Postby Solarwinds » Sat Jul 09, 2016 11:33 am

I will admit, I've never used glue nor 5200 to repair a sail, but there are plenty of videos/discussions on using adhesives including 5200 and they don't seem too crazy. The original posting in this thread was for a repair to an ORIGINAL sail which may put it at 20 - 50 years old. Mine, I'm pretty sure, are original and that would put them at around 55 years old. If sails are old, and have gotten a lot of sun the yarns are decayed, that's why they tear. Adhesives penetrate the yarns and should make a longer-lasting repair, the needle penetrating the fabric will probably destroy it even more and the thread will have nothing to hold on to. IMHO, getting original sails properly repaired is just money down the drain when there are inexpensive, new alternatives out there.
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Re: Sewing Dacron sail tape

Postby KingsTransom » Sat Jul 09, 2016 12:33 pm

Thanks for the replies. The boat was made in 1975, and has sat in a garage, with the sails in the cuddy, for the last 29 years. Assuming 12 years of use, there's probably modest sun damage. Being as old as they are, I am only hoping for a season or two to see how she sails before investing in a new set.

I'll give the machine a try, using silicone spray on a cotton swab, wiping the needle periodically. If, after one patch, I see evidence of gumming the works, I'll switch to hand sewing. I have an Elna SU, which I've used to lap-sew my Honda's seat belts back together after my dog chewed through them which, by the way, looked as if he'd used scissors. I used 1 oz. nylon thread for that job. The machine did not balk at all. That job accounts for the sum total of my machine sewing experience. The largest needle I have on hand is a 110//18, which looks large enough to accommodate pretty thick thread. What local retailer might carry the thread you mention? Amazon sells a UV-resistant V69 polyester thread for outdoor furniture; So far, my boat IS outdoor furniture.

A square zig-zag makes sense to me. The book I have suggests stitching such that the inner set of points are on the patch and the outer set of points are outside the edge of the patch, on the sail only. Are you saying it's best to keep all points on the patch?

There are also tears near the base of a couple of the batten pockets. Since sewing there would shorten the pocket and tape may stick to the batten, I would appreciate suggestions how to fix that.

Thanks,

Scott
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Re: Sewing Dacron sail tape

Postby FloridaTom » Sat Jul 09, 2016 1:02 pm

You're correct - That the adhesive IS stronger than sewing on old sailcloth.
I've had to take apart sails that were seamed with acrylic seam tape when they were first sewn, and it's obvious that it's the seam stick adhesive holding them together, when the seam sewing is completely sun-rotted away.

The original poster had already covered the tear with Dacron sticky-back, on both sides.
In this case, the sewing actually just serves to keep the edges of the tape stuck down.
He's really just sewing 2 layers of new Dacron together, sandwiching the old, so I do think it's a good repair.

As to the 5200, I meant no offense, but I think it's too easy to just make a mess with the stuff.
I guess I was speaking to emergency repairs in general, without being specific as to the sail's age.
I'm sorry if I was less than clear.
Keeping some peel and stick sail tape in the ditty bag is a good idea, and better than a lot of alternatives.

You're also right about some sails just being too old to bother repairing, properly or otherwise.
Sometimes get a few more miles out of them, but .......
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Re: Sewing Dacron sail tape

Postby FloridaTom » Sat Jul 09, 2016 8:01 pm

Sorry, Scott - I was answering about the 5200 - I missed your last post.

If you can use a #18 needle in the machine, you can probably use the V69 - That would be ideal.
We buy thread from a sailmaking supplier, but if you can get UV rated V69 on Amazon, go for it if the price isn't too bad.
Be sure your tensions are good - Important with hard sailcloth, as the thread cross-over won't bury like it will in softer seat belt web.
Make up a test sandwich of a couple layers of your sail tape to check.

In some cases, it's good to step over the edge like you describe, but in this one, I think it's better to keep the sewing on the patch.
The major strength is in the new cloth of the patch, not in the older cloth of the sail - What you're aiming for is to keep the patch from lifting.
Just put your good reading glasses on (if you're of a certain age ;~)), and get close to the edge but not over .
Don't stress if a couple stitches get away - It'll be fine.

I'd need to see a photo of the batten pocket tears, before I could suggest a plan of attack on that.

Tom
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Re: Sewing Dacron sail tape

Postby KingsTransom » Fri Sep 23, 2016 4:22 pm

I sewed the sail patches and also over the fraying stiches on the batten pockets with V-69 polyester thread using a 110 needle and silicone needle lube. The needle still got gummed up, but it worked OK anyway.

I noticed that the jib & main are from different sailmakers, the main from Neil Pryde and the jib from Atlantic Sails of Portland, Maine. Why is the jib foot always lower than the mainsail foot? In my case, it makes it impossible to see under the jib, and the window is so high you would need to stand to see the horizon through it. Being so low also means the jib catches on the mast tabernacle.
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Re: Sewing Dacron sail tape

Postby GreenLake » Fri Sep 23, 2016 5:38 pm

You want the jib to "sweep" the deck to increase its efficiency.

The pressure on both sides of a sail is different. By blocking the path around the bottom of the sail, you prevent the pressure from equalizing there. As that pressure difference is what makes the sail provide lift, a good jib will sit low.

The window in the jib is usually positioned correctly for someone sitting on the side of the boat when going upwind. This normally works well in all but very light winds, because at least one member of the crew usually does sit out.

Event though some people still have "original" sails, the truth is, sails just don't last as long as hulls do, and if you use your boat regularly should be replaced every so often. I've put between 200 and 300 hours on my latest sails over a number of years and they are now showing definite signs of age.

Your boat having sails from two different makers shows evidence that some previous owners replaced sails. (I suspect sail windows are a recent invention and that early generations of the DS were all shipped without them).
~ green ~ lake ~ ~
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Re: Sewing Dacron sail tape

Postby talbot » Mon Oct 10, 2016 12:36 am

A skipper I race with estimates that his sails last about four years before he wants to replace them. This is on a 25' boat where the replacement is a big investment, particularly because this is a crowd that buys competition-quality sails. A year for these guys is probably about 100 hours of use in twice-weekly races over 5 months. I think 400 hours is about right. I have a set of Intensity sails with about that level of use, and I think the shape is much less efficient now. The "sweep" of the jib is all but lost. Close-hauled, the sail creases from tack to clew. The telltales say the jib is pulling fine, but the curved foot flutters uselessly in the wind. I tend to ease the sheets and fall off just to get rid of the crease. It's a lousy heading, but the aesthetics of the blown-out sail are just too embarrassing.

BTW, the original Neil Pryde jib did not have the deeply curved foot. Not sure if new NP sails do.
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Re: Sewing Dacron sail tape

Postby GreenLake » Mon Oct 10, 2016 3:39 pm

Having a sail "flutter" will destroy it more quickly. So once it doesn't set correctly, there might be some workaround for a while, but after that, it's done.

And unless your sailing is true gentlemanlike (gentleman never sail upwind), limits on how well you can point may matter.

There's a particular cruise around here that I've done a number of times, in somewhat varying conditions. It starts with a nine mile upwind leg to the destination, then lunch, ice cream or dinner, depending on the time of day and a downwind return. (Obviously, putting the upwind leg first makes this an attractive destination, but that's another discussion).

I've sailed it with old blown-out sails and then with fresh sails. The difference didn't feel that pronounced while sitting in the boat, but when I compare the number of tacks and the time taken, it's clear that the new sails allowed me to point much higher (and get there in a bit more than half the time).

On a reach, or downwind, you won't notice the difference as much, but going upwind, with perhaps a bit of adverse current, seemingly small differences in tacking angles will add up.
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