BYYB Forums

Hi guys,

I do canvas work as a sideline. Primarily I make pavilions and tents for historical re-enactments.

My question is this: I use a canvas called Sunforger.

It is a 10.38 oz cotton duck that is marine finished, boatshrunk, mildew resistant and flame retardant. I get it in 42" widths for about $5.00/yd after shipping.

If anyone is familiar with this cloth, is it suitable for sails?

Also, I know on older gaff rigged sails they put the belly into the sail during the roping process.

Does anyone have any info on sail shape as far as belly goes if you are making the sail out of strips of fabric as opposed to a one-piece tarp?

Thanks,

David G.

10.3 ounce fabric is very heavy stuff for the small sails seen on these little yachts. Typical sail material is half that weight and less in many cases.

The panels in traditionally made sails are used, because of the bolt widths generally available, in the fabrics used in sail making. More importantly, the fiber orientation can be maximized to the load with narrower panels then with a tarp (seams too). Panel layout is a bit of black magic and science. Panel layout software is available (useful products aren't cheap), but the kicker (just like with yacht design software) is you have to understand what shapes you want for the sail you're building. You can assemble a nice looking sail with considerable expertise, but if the panel developments were not well suited to the application, then they'll not set well and provide less then optimal drive. Ask anyone who started with a home made tarp rig and then bought a real set of sails to compair the two sets.

Much of this can be eliminated with a SailRite" kit, but you don't really save much over purchased sails and have to do a lot of work, to get an end result that will set and work well on your boat.

The actual panel seams and reinforcement work is pretty straight forward. The hand work can be very difficult, as there is a surprising amount on even a small sail.

You could get an idea of panel shaping with good tarp material, not the 10 x 10 - 800 stuff or 12 x 12 - 1000, most end up using, but the good 14 x 14 weave, 1200 denier and make up some sails. They don't have to have all the pieces, just the panels so you can estimate the amount of luff round you need for the mast bend you anticipate (ditto the gaff and boom), amount of roach you can carry, how much draft, where to put it for a good set, etc. Getting this information from a sail maker, is like pulling teeth or asking a head mechanic why his car is faster, then the rest of the competition. Software can give you a general idea, but it usually has so many adjustments and variables, that designing a panel layout is equally as difficult.

Examples of these issue would be, you want to make a gaff main for a Weekender and you know your mast isn't very bendy, so you settle on a small amount of luff round, say a few inches. The software places this at a default height of say 40%, but this is based on a typical Bermudian rig, not your stiff stick gaffer. Should you use this or move it up or down some? The panel layout suggests (by default again) a camber at 28% of the chord, but you do mostly light air sailing so you'll need more, how much and where do you put it? Just like the new yacht design software available in the market, the sail design stuff assumes you have an understanding of the principles and concepts and provides some general guides, that work sort of well on a typical modern yacht. Toss in some oddities or spicific needs and the software is very adjustable to account for your every whim, but you need to know where things should go.

Thanks Paul,

It sounds like there is a bit of a balancing act as far as weighing out the various needs and that no one suit of sails will be ideal.

I suppose the middle road is what most of us have to find depending on the conditions we most often sail in.

So. . . as this sort of thing fascinates me. . . I know I'm a geek. Do you reccomend any good reference works for learning sail design, and are there any works that detail the extra anomalies involved with gaff rigs?

I have read and re-read the sailmaker's apprentice and made the ditty bag, but that is a long way from understanding drive, etc.

What weight is oceanus sailcloth?

Btw, If Jim Stumpf or any of the semi-local guys need sail covers or other oddities when the weather gets nicer we can have a picnic and a "stitch and bitch" as my wife calls them at my place and work on some projects.

Let me know in advance and I will clear out the shop so the piles of fabric won't topple and kill anyone. lol.

Dave G.

I've attached a gaff mainsail, panel layout drawing from one of my designs. It's similar in size to a Weekender, but has a higher peaked gaff. Looking at the gaps between the panels you see the subtle tapers developed in, to provide shape (at very specific locations), the laps (seams) are marked with a dotted line. The amount of luff, foot and leach round is suggested by the gray lines, which will be straight when the panels are sewn together. This particular sail has been made a few times, sets and draws well. It has three battens.

http://byyb.org/cpg143/albums/userpics/1...ality=Full[/url]

Sail cloth, regardless of material type or construction method is available in many different weights. Typical weight for a small, light weight sailing craft is 4 to 6 ounces. High tech fabrics, which would include Oceanus (good stuff, but bring your purse), can differ, sometimes substantially, basically because of the construction techniques and the physical properties of the fabrics.

I still can't get the image to apear in the post, just the link

Paul, you need to click on the Img button before and after adding the photo link instead of the url button

I've done that (IMG button) and also tried the URL button too. I think my firewall is causing a problem.