View Full Version : Traditional canvas sails

12-06-2002, 12:28 AM
Yup, yet another sail material question, gotta keep out of HomeDepot. ;)

I saw some rather nice looking painter's canvas while I was there. Had a nice tanbark color to it, and the price was nice.

So what's the downside to traditional canvas?
I know it will absorb water, and weigh a TON when wet.

How does it hold it's shape?
For that matter why was it given up?

12-06-2002, 12:36 AM
I've never had cotton sails, but from what I've heard, weight and the need for closer attention to drying properly are two concerns. Also that sythetic sails hold their shape better longer.

The simplistic (and doubtless somewhat erroneous) explanation is that in a cotton sail the fibers are free to move, and are more prone to inelastic stretching. In a dacron sail, the fibers are less stretchy, more elastic, stronger, and often the sail is impregnated with a binder.

And I'll wager there is a world of difference between a painter's tarp and cotton sailcloth.

[ 12-06-2002, 01:39 AM: Message edited by: ishmael ]

Todd Bradshaw
12-06-2002, 01:46 AM
Natural canvas stretches, shrinks, mildews and is at least twice the weight for the same amount of strength and stability as Dacron. It does have pretty decent U.V. and abrasion resistance. Chances are that the stuff you find in Home Depot isn't tightly woven enough to work very well and unless you plan to build a ship, it's pretty heavy for the job. If you want to make a canvas sail, buy some 10 oz."Sunforger" canvas. It's the best commonly available brand of good stuff. All in all, you would still be better off to spring for Dacron.

12-06-2002, 04:57 AM
Well, I can remember Egyptian cotton sailcloth, and it was not much like painter's canvas. It was very tightly woven.

The sails I have been using for the past 16 years are a polyester/cotton mixture, with each thread having two parts, a dacron inner and a cotton outer layer. So the Dacron in the middle is protected from UV and chafe, but is there to add strength. This material will mildew if anything even quicker than a pure cotton will, but my sails are oil and ochre dressed and I do my best to keep them nice. I am very happy with them. Unfortunately this material is hard to come by and at present it is available in only one weight, apparently.

Cotton sails are quite practical, provided you always stow them dry. Flax sails stretch more, are much heavier to handle, and can sometimes be stowed slightly damp!

12-06-2002, 07:31 AM
Brian I made a painters tarp sail for my sharpie when it was sprit rigged. About the only thing I can say is it was cheap (less than $50). Be careful because a painters tarp will have seams just about anywhere they want to put one. Look closely at the image I've posted here. This was a "single" piece of painter's tarp. All we had to do was cut it out and hem the edges. The seams you see running through the sail are from the factory.


My sail also mildewed after the first sail. When I built my lug rig we bought seconds from sailrite and only had $90 in material and I've been much happier with it.


12-06-2002, 11:20 AM
I'm surprised that dacron needs any UV protection.
We've had a dacron line (one of our dogs was inclined to wander when out with us and get herself in trouble :rolleyes: ) hanging on the back of our house in full sunlight for about 20 years and no noticable degradation.

Todd Bradshaw
12-06-2002, 03:35 PM
Some of the better quality Dacron sail fabrics have U.V. resistant stuff mixed into the coating and it makes a difference, though it certainly doesn't make the fabric U.V. proof. On a piece of rope, the outer surface is getting most of the U.V. and the inside is being shaded, so it doesn't get much. On a piece of sailcloth that's only about as thick as a piece of heavy paper, there is no inside. All the fibers are getting U.V and none are protected.

A typical cruising sail, used but well cared for and stored under a cover will probably use half of it's tear strength in 8-10 years in a moderate climate. This is one reason that as long as you're within a reasonably similar fabric weight range, you can patch a sail with a different fabric. Even if it's not an exact match, it will usually be quite a bit stronger than the old fabric around the patch. This is why when you take a sail in to be fixed the sailmaker doesn't have to get out the micrometer to check thickness and the magnifying glass to do a thread count before deciding whether he has an appropriate chunk of repair fabric.

In the case of roller-furling jibs that don't have proper protection two or three seasons can deteriorate the exposed leech and foot areas enough that they tear like tissue paper.

This is one of the frustrating things about my work. No matter how well I do it and how much effort I put into sail design, construction, reinforcement and fancy-work. I can be pretty sure that it's reasonable lifespan is likely to only be 10-15 years maximum. Nobody is going to be restoring my old sails 100 years from now and calling them classics. Fifteen years after I'm gone, they will be too. Oh well, such is life... In exchange, I have the satisfaction of knowing that when one of my customers is out sailing his boat, from fifty yards away the part that I built has as much to do with how the boat looks on the water as the part that he built.

James R
12-06-2002, 04:50 PM
I raced Snipes in my younger days - wooden boat, wooden mast, galvanized rigging, and cotton sails. I had two suits of sails, one for racing the other for everyday sailing. I saw more than a few new sails ruined by rough use in heavy weather. Invariably the leech would be stretched permanently so if the wind piped up I would use my everyday sails even in a regatta. You could easily spot sails that were past their prime or that had been abused - they would be visibly misshapen.

We treated our sails almost with reverence. There was a mystique associated with breaking in our sails and everybody had their own little secret methods. As for taking care of our sails we didn't really do anything out of the ordinary. At the end of the day, if the sails had gotten wet, I would rinse them and hang them by the head and tack from the clubhouse rafters to dry. Putting sails away wet was a sure invitation for mildew. Aside from that the only other maintenance I performed was to occasionally inspect and repair the batten pockets.

As others started racing with dacron sails I started to drop back in the fleet. I was still in the top third but I really hated losing back then. Once I got myself a suit of dacron sails I started to move up in the fleet again. I remember my first race with my new sails. The wind was blowing strongly against the tide. I was tearing along on a broad reach and headed up to blanket and pass the boat ahead of me for the lead. I flew off what seemed like a standing wave and fell into the trough. The starboard shroud broke and the mast just snapped at the partners. A couple of weeks later I was back on the water with a spliced mast and new stainless rigging.

I loved that boat too. I can't remember the exact hull number but it was in the 9000's. The deck was planked with mahogany strips, the seams filled with white caulking, and finished bright. The cockpit was very shallow - the floor was level with the top of the daggerboard case. I've never seen another Snipe like that. Every January I would spend an inordinate amount of time wet sanding the hull and painting it with a dark blue enamel. After letting the paint harden for a couple of weeks I would flip the boat over and sand and varnish the deck. Memories... smile.gif

James R
12-06-2002, 05:06 PM
Oh and to answer the original questions: yes cotton sails do weigh a ton when wet, no they don't hold their shape as well as synthetic sails, and as ACB has mentioned, painter's canvas is nowhere near the same thing as egyptian cotton sailcloth. But, if all you want is a cheap sail so that you can get out on the water do it. I remember seeing in one of the WBs brazilian fishermen using a material similar to Tyvek (housewrap) to make sails for their boats. You, and they, certainly won't win the Cup and the sail may only last a season but so what. What's important is getting out there.

12-08-2002, 10:40 AM
Thanks folks
for the advice, the stories, and most importantly the inspiration!