Polytarp lugsail 3D shaping

[laukejas]

The Trimaco Eliminator is £29-42 for a sheet measuring 2.74 x 3.65 metres, a fraction over 10 square metres. In the UK, Tyvek is available only in rolls of 100 metres length, either 1.4 or 2.8 metres in width, for £119-20 or £226-00 respectively. I would expect the 2.8 metre width to be more useful & if you could buy 4 linear metres that works out to be £9-04 for 11.20 square metres, a saving of £20-38 or €28.11. How big is your sail?

For me personally, I prefer the Eliminator cloth as it would be much quieter than the Tyvek. Also, Du Pont would not be getting free advertising each time I set sail. OTOH, if you can blag some Tyvek from the manager of a building site. :?: :?: :?:

Regards,

Perry

I don't get what's with the noises that Tyvek supposedly makes. I sailed with Tyvek sails, and didn't hear any rattling. Maybe it was a different kind of Tyvek? At hardware store, it was named Tyvek Pro, and it was green on one side.

As for the cloth you suggested, remember, I'd have to pay for shipping too, which may be a lot. I'm in Lithuania

since you plan to use this sail in light weather it will not matter much between tyvek and polytarp. Use which ever you can get cheaper, your first sail will not be your last one, so go cheap and just plan on learning on it. Take what you learn to the next one you make. I have used both, both work just fine for low cost sail. in a heavy blow you will stretch and damage either one, so just go with what ever you can get cheap.

I have used cheap duct tape on tyvek, one sided. you do not need two sided for a test sail, it just will show on the outside. you can put another strip on the back side if you want more strength. I have used cheap clear packing tape on polytarp, but the adhesive does not last very long in sun light, the duct tape is much more durable, and stronger. You can make it really strong by using duck tape reinforcement at the corners and along the seams, not pretty nor light, but it will make a strong and durable sail.

I think you can find images of the different types of seams on the internet, I have seen them. You do not need the book really (I have read it), but it mostly talks about making durable permanant sails, not quick polytarp sails. there is also not a lot about design in it, but how to detail the seams, attachments, and other important details. I have not used any of the methods he outlines becasue they are costly and very time consuming. I will stick with duck tape and tyvek for now, some day I may actually buy some real sail cloth and actually sew a permannat sail. but really, putting together a sail with duck tape is very fast.

I would keep the seams to a minimum, just put the amount in you need to get the shape. The darts will work fine.

good luck.

attached is a gray poly tarp sail with gray duct tape, you can not see it but it is there, and a green poly tarp sail that worked well, it uses yellow duct tape for the color, but cheap gray would work too. the other is a Tyvek sail using white duck tape, the shape came from a curved luff, no seams. It too worked well.

Well, you make it sound like I should just make a quick and dirty sail for testing and improving my skills, so that I can soon switch to a "real" sail. But you see, the problem is that I'm unlikely to ever get a real sailcloth. I searched and searched, and it is simply not available. Either I ship from US and pay twice for shipping, or start my own sailcloth manufacture.

With that in mind, Tyvek is probably the best material I'll ever get. That means I'll likely use this sail for a long time. Wouldn't it be reasonable to put considerable effort in this sail, and even though material is inferior, try to at least make it like sails are supposed to be made?
Todd Bradshaw said that sailmaking process and methods used are important than material used.

Please take a look at this sail. This guy clearly put a lot of effort, and if we were to believe him, results were satisfactory.

I'm not arguing against what you said, just thinking out loud. If I'm likely to sail for a long time with this sail with no opportunities to upgrade, should I really go quick and dirty?

 

[ch3oh]

Why not look at some of the Hitech building tarps with reinforcement laminated in?

Like this one? It's Icopal monarflex 160gsm scaffolding cover. Don't know how it handles the loads yet.

 

[myszek]

Polytarp sails needn't be quick and dirty. If a sail is not very high-tensioned (lugsails ar moderately tensioned, in compare to staysails), it can be used many years.

Janusz Ostrowski made a polytarp crabclaw sail for his proa (photo 1) in 2006. He still uses it, sailing year by year along Baltic sea coast. He glued his sail with double-sided tape, then sew it. The work was easy, since crabclaw sails are cut flat.

Andrzej Nowacki glued his crabclaw (photo 2 - my design proa) in 2012. He is sailing near Szczecin from April to December, and is still planning to sew his sail.

Przemek Herbut made sloop sails for his Aurora (photo 3 - also my design) using Sailcut software. They look very professional. I don't know, whether Aurora is still sailing, as Przemek sold her 2 years ago.
All of them used 120g/m^2 polytarp.

At last, my experimental "battened spinnaker" (photo 4) made of 2 vertical sheets of polytarp, with 3 darts at each luff. I glued it with double-sided tape, then strengthened with some duct tape. Battens are made of PVC tubes. It worked!

regards

krzys

 

[ch3oh]

"Aurora" looks very nice, got any more pictures? I like the idea of having a good design and working reinforcements despite using somewhat unorthodox materials to save money. At least one learns to be a better sailmaker spending those hours cutting and sewing, so the next set has a lot lesser change to end up a pile of pentex scrap.

 

[Petros]

Well, you make it sound like I should just make a quick and dirty sail for testing and improving my skills, so that I can soon switch to a "real" sail.

With that in mind, Tyvek is probably the best material I'll ever get. That means I'll likely use this sail for a long time. Wouldn't it be reasonable to put considerable effort in this sail, and even though material is inferior, try to at least make it like sails are supposed to be made?

I did not say anything about "quick and dirty", spend as much time as you feel necessary on your first sail. You may like it and use it for many years, I have used mine a very long time (some I have are almost ten years old). All of the duck tape and polytarp sails I have made I am still using many years later, some I have even installed on new hull designs after discarding the old one that I did not like. They hold up quite well without sewing, occasionally I have to do some repairs or rework on it and it is easier to rip off tape and redo it rather than stitching. Tape can actually make a stronger seam, it spreads the loads over a larger area without puncturing the fabric. Consider that the strength of a sewn seam comes from a closely spaced row of holes with thread running through it, not exactly a strong attachment on a film type fabric. Glue and tape are much stronger.

My point is that despite the effort you make on your first sail, you will likely want to experiment and make changes after you use it, if not make an entirely new one. Rather than be disappointed and reluctant to make changes, just expect that after your first one you will likely find ways to improve it. The idea is to plan on it, and design and build the best sail you can, but not to spend too much money on it nor go to any extra effort to sew it when taped seams work perfectly well. Tyvek works perfectly well, it is usually lighter than polytarp too, but if one has a significant price advantage over the other, that is the one I would use.

That tyvek sail on the link you posted is rather impressive piece of work, but Tyvek does stretch and break down in sun light eventually. so that much work seems a lot of effort for something that will not hold up very long. Unless of course it is just a test build.

As far as "real" sail cloth, I have a suggestion that I have been considering, but I have not tried yet. Sail cloth is just polyester treated with UV stabilizers and plastic coatings to stabilize the fabric, and give it a smooth finish. I presume you can get plain polyester fabric where you live, it does not have to be particularly high quality, just the correct weight. After you sew it together with the shape and reinforcements you want, than give it several coats of gloss Exterior Latex paint, thinning the first layer with Latex conditioner. this will give it UV protection, a smooth finish (since you would fill the weave), it will help stabilize the shape, reinforce and protect the stitching, and you can get any color (or color combinations) you want. And it would be cheap. I have tried this with Tyvek to cover up the Logo (no free advertizing!) and it works quite well, it does add some weight to the fabric, but not much, and the price is right. Oil based paint would work too but it becomes brittle and will not flex as well for stowing it.

 

[laukejas]

I did not say anything about "quick and dirty", spend as much time as you feel necessary on your first sail. You may like it and use it for many years, I have used mine a very long time (some I have are almost ten years old). All of the duck tape and polytarp sails I have made I am still using many years later, some I have even installed on new hull designs after discarding the old one that I did not like. They hold up quite well without sewing, occasionally I have to do some repairs or rework on it and it is easier to rip off tape and redo it rather than stitching. Tape can actually make a stronger seam, it spreads the loads over a larger area without puncturing the fabric. Consider that the strength of a sewn seam comes from a closely spaced row of holes with thread running through it, not exactly a strong attachment on a film type fabric. Glue and tape are much stronger.

My point is that despite the effort you make on your first sail, you will likely want to experiment and make changes after you use it, if not make an entirely new one. Rather than be disappointed and reluctant to make changes, just expect that after your first one you will likely find ways to improve it. The idea is to plan on it, and design and build the best sail you can, but not to spend too much money on it nor go to any extra effort to sew it when taped seams work perfectly well. Tyvek works perfectly well, it is usually lighter than polytarp too, but if one has a significant price advantage over the other, that is the one I would use.

That tyvek sail on the link you posted is rather impressive piece of work, but Tyvek does stretch and break down in sun light eventually. so that much work seems a lot of effort for something that will not hold up very long. Unless of course it is just a test build.

Okay, I see your point. Sorry for misunderstanding. Since the sail will be one of the last things I'll do in this project, I think I'll decide there and then, depending on the time, budget and patience I have left. Thank you for this piece of advice.

As far as "real" sail cloth, I have a suggestion that I have been considering, but I have not tried yet. Sail cloth is just polyester treated with UV stabilizers and plastic coatings to stabilize the fabric, and give it a smooth finish. I presume you can get plain polyester fabric where you live, it does not have to be particularly high quality, just the correct weight. After you sew it together with the shape and reinforcements you want, than give it several coats of gloss Exterior Latex paint, thinning the first layer with Latex conditioner. this will give it UV protection, a smooth finish (since you would fill the weave), it will help stabilize the shape, reinforce and protect the stitching, and you can get any color (or color combinations) you want. And it would be cheap. I have tried this with Tyvek to cover up the Logo (no free advertizing!) and it works quite well, it does add some weight to the fabric, but not much, and the price is right. Oil based paint would work too but it becomes brittle and will not flex as well for stowing it.

That is an interesting idea, I have never heard of anyone attempting to make polyester sail in this manner. But then again, it's not like I know a lot.

What would be appropriate cloth weight to look for? When I considered making SOF boat, I couldn't source ANY kind of polyester fabric that is heavier than bedsheets. In fact, I couldn't find any kind of raw fabric, just finished products (bedsheets). Anyway, sails would require lighter fabric than SOF boat cover. I could try black market too, haven't considered that before.

So, what weight would you say is appropriate?

 

[Petros]

I have never heard of anyone doing either, it was an idea I got after reading a book about sail design and performace, there was a whole chapter on the different kinds of sail cloth available. I thought, I can make fabric like that; I have made perhaps 20 skin-on-frame hulls, and have painted both tyvek and polytarp sails to get the color I wanted. Painting a sail seemed the natural thing to try.

sail cloth is typically 3 or 4 oz per square yard, up to six or 7 for very large sails. That would be the finished weight, with the coatings. On something that small I would think something in the 2 to 3 oz. range before coatings would be fine (not sure what that would be in metric). heavy bed sheet fabric would do, any color or pattern you want. I have bought a roll of printed polyester fabric from a second hand store to use a the skin on a two man kayak, it just got painted over anyway, the color or pattern was not relevant (though it took several coats to hide the pattern).

It is said to use only raw fabric, not finished, but I have used both and it makes no difference. The paint does not bond to polyester fibers at all, it must soak through it and encapsulate it (I read that in a book on fabric covering a light aircraft), so finish is not relevant, it will not stick to it raw or finished, but you have to soak the first coat through the fabric to the back side, and subsequent coats are to fill the weave to get a smoother surface. Once the fibers are encapsulated by the paint, it will stick and stay stuck. It was the combo of the book on sail design (sail cloth) and the one on covering light aircraft with polyester fabric. It got me thinking about painting sails to make them stiff and more UV resistant. Stretch the sail smooth and tight, iron it with a very hot iron to flatten the fibers and get any wrinkles out it. Than with it stretched tight, paint it, use latex conditioner and it will flow nicely into the weave, soaking through and filling it nicely. two minimum coats, three coats should give good coverage and a smooth surface, and still be flexible enough to stow it easy. Again, try it with left over house paint and bed sheets to see how it works. I am sure you must have surplus or used clothing stores there that sell used bed sheets or left over fabrics.

 

[myszek]

"Aurora" looks very nice, got any more pictures? I like the idea of having a good design and working reinforcements despite using somewhat unorthodox materials to save money.

Aurora was designed and built as a low-cost boat. Her hull is origami ply shell made of 4mm plywood, covered with 2 layers of glass cloth. Wooden mast, polytarp sails. I sailed her once, she proved to be a very pleasant boat.

I have many photos of the hull, unfortunately only one picture under the polytarp sails.

regards

krzys

 

[laukejas]

I have never heard of anyone doing either, it was an idea I got after reading a book about sail design and performace, there was a whole chapter on the different kinds of sail cloth available. I thought, I can make fabric like that; I have made perhaps 20 skin-on-frame hulls, and have painted both tyvek and polytarp sails to get the color I wanted. Painting a sail seemed the natural thing to try.

sail cloth is typically 3 or 4 oz per square yard, up to six or 7 for very large sails. That would be the finished weight, with the coatings. On something that small I would think something in the 2 to 3 oz. range before coatings would be fine (not sure what that would be in metric). heavy bed sheet fabric would do, any color or pattern you want. I have bought a roll of printed polyester fabric from a second hand store to use a the skin on a two man kayak, it just got painted over anyway, the color or pattern was not relevant (though it took several coats to hide the pattern).

It is said to use only raw fabric, not finished, but I have used both and it makes no difference. The paint does not bond to polyester fibers at all, it must soak through it and encapsulate it (I read that in a book on fabric covering a light aircraft), so finish is not relevant, it will not stick to it raw or finished, but you have to soak the first coat through the fabric to the back side, and subsequent coats are to fill the weave to get a smoother surface. Once the fibers are encapsulated by the paint, it will stick and stay stuck. It was the combo of the book on sail design (sail cloth) and the one on covering light aircraft with polyester fabric. It got me thinking about painting sails to make them stiff and more UV resistant. Stretch the sail smooth and tight, iron it with a very hot iron to flatten the fibers and get any wrinkles out it. Than with it stretched tight, paint it, use latex conditioner and it will flow nicely into the weave, soaking through and filling it nicely. two minimum coats, three coats should give good coverage and a smooth surface, and still be flexible enough to stow it easy. Again, try it with left over house paint and bed sheets to see how it works. I am sure you must have surplus or used clothing stores there that sell used bed sheets or left over fabrics.

That's a very interesting idea. If you have time, I'd like to discuss it further. When I planned to make folding SOF boat, I had to abandon the idea because I realized that if I went with painted polyester fabric, even latex paint would crack after folding the skin. I wonder if the same would happen with sail made this way, considering that sails get a lot of bending, twisting and crunching. Of course, one could go with non-reefable, non-foldable sail like ones found on windsurfers, but they have very limited use.

Petros, you have extensive experience in SOF boats, I believe. Have you ever done a folding SOF boat? What would you say are the limits of latex paint flexibility before it cracks?

I'm wondering if varnish is any more flexible than paint. I should read about how Dacron is laminated, and what kind of chemistry is used there. Perhaps some if it can be re-created in garage conditions.

P.S. As for experiments, I don't really have materials or time to do it now, but I'll certainly put it in my ideas list for free time.

 

[Petros]

latex painted fabric folds up fine, I discovered this when I painted the tyvek sails. the are pack-up without regard to it being painted. On polytarp the paint eventually flakes off, but not so far on woven fabric. Latex is fairly flexible and should not be a problem with only two or three thin coats on it.

If it starts to flake off eventually, you just put another coat of paint on it.

I have made several folding skin-on-frame kayaks, but I used some costly and toxic hypalon paint (uses xylene as the solvent, melts just about everything plastic). It is tough and durable, but not easy to work with becasue it costs so much and takes special brushes and thinners (and highly toxic).

Latex paint is not particularly good as a skin sealant because it has low abrasion resistance. but otherwise it is excellent, inexpensive, drive fast, soap and water clean up. It takes 6 or more coats to make a skin fully water tight, and it must dry between coats (fairly fast in warm weather), and it can not be applied in damp weather or it will not cure very well. On a sail however, it does not need to be water tight, nor is abrasion as much an issue since, unlike the hull, it will not be dragged over the beach or a dock.

If the sails are carefully folded, or better, rolled up, several think coats of layex I would think holds up very well. I will have to try that sometime if I ever make a more "permanent" sail than tyvek or polytarp. All of my builds are "experiments", so I am a long way from being at my final design.

 

[laukejas]

latex painted fabric folds up fine, I discovered this when I painted the tyvek sails. the are pack-up without regard to it being painted. On polytarp the paint eventually flakes off, but not so far on woven fabric. Latex is fairly flexible and should not be a problem with only two or three thin coats on it.

If it starts to flake off eventually, you just put another coat of paint on it.

I have made several folding skin-on-frame kayaks, but I used some costly and toxic hypalon paint (uses xylene as the solvent, melts just about everything plastic). It is tough and durable, but not easy to work with becasue it costs so much and takes special brushes and thinners (and highly toxic).

Latex paint is not particularly good as a skin sealant because it has low abrasion resistance. but otherwise it is excellent, inexpensive, drive fast, soap and water clean up. It takes 6 or more coats to make a skin fully water tight, and it must dry between coats (fairly fast in warm weather), and it can not be applied in damp weather or it will not cure very well. On a sail however, it does not need to be water tight, nor is abrasion as much an issue since, unlike the hull, it will not be dragged over the beach or a dock.

If the sails are carefully folded, or better, rolled up, several think coats of layex I would think holds up very well. I will have to try that sometime if I ever make a more "permanent" sail than tyvek or polytarp. All of my builds are "experiments", so I am a long way from being at my final design.

Well, I don't know much about it, but I can't see why your proposal wouldn't work. It seems like a great idea. I'm wondering why there are no attempts to make such polyester painted with latex sails. At least I haven't heard of any. I'm wondering how would these kind of sails perform.

It wouldn't hurt to try. I'll have to find some decent polyester cloth of your suggested weight and try to make a large sample.

If you'll do any experiments before me, please post the results! I'm sure this would be very interesting to many, and who knows, maybe it might turn out into another low-cost sail revolution.

 

[laukejas]

Petros, I've just discovered that some people use iron on vinyl to laminate cloths.

Take a look.

I haven't found any information on how durable is this, nor is it strong enough to be used as sail material. But it seems promising.

What do you think?

EDIT: I wonder if PET or PVC film can be used instead of vinyl.

 

[Petros]

I was considering the latex painted sails for the "hardward store" class of sailboats I have been working on getting going. Laminates would also be good, but costly. That film would likely cost more than regular sail cloth. If I build one later this year I will report the results on this forum.

I had also thought of laminating using say mylar on tyvek or polyester fabric, using a spray on adhesive. It would be very difficult I think to get large sheets of fabric to laminate smoothly over the whole surface without wrinkles or puckers. Mylar films are pretty tough, but any plastic film that strong is not exactly free. Cheap stuff like polyethylene could work too, at much less cost, but it would not add any strength. It would make for a smooth surface however.

All and all I think painting on a layer of latex would be far easier, and it has proven to be tough and reliable for skin-on-frame hulls, so it should work fine for a sail.

 

[ch3oh]

I don't think latex painting adds anything other than colour and weight. Think about cotton sails, they were pourous and wouldn't hold air but they still pushed the boats. Invest the extra weight on thicker polyester to get a better sail. PVC or "vinyl" are also no good plastics in sailmaking as they stretch. You can get thin mylar heat laminate 1400mm wide for 160€/roll of 50m. Printhouses use them. Won't end up cheaper than a dacron sail but it's the way to go if you want to only get lined up high modulus fibres in your sails

 

[ch3oh]

Has anyone attempted to build a spinnaker using cheap grade ripstop nylon? It's about 1/3rd the price of a good silicone coated sail fabric. It's meant for light raincoats and camping gear and has some water-repellent treatment and is not "ground" to be soft like stuff for clothing.