Anonymous wrote:It's not a lack of coating that should cause you to avoid this cloth. Try holding it up to a strong light - can you see pinhole-size leakage of light through it? If not, it's tightly woven enough. If it can be used for kites and tents, as the supplier claims, then it's airtight enough for a lightweight sail. It's similar to the cloth I used for my windvane, which is still strong (but faded, as it's red) after two full seasons of exposure to UV. [ ... ]

David,

I have been trying to decide if I see pinhole-sized leakage of light through these fabrics or not. If anything the one that clearly shows points of light is the Odyssey sample. But I expect this might be because the Odyssey is more or less opaque in normal room light and all the other fabrics are at least somewhat translucent.

Capturing these differences in a photo is even more difficult but I gave it a try anyway. Its not cold enough for skiing and not warm enough for sailing so why not waste some time on this?

I used a portable shop lamp with a 60 Watt equivalent LED bulb for the photos. I also cut a hole in some cardboard and wrapped in it aluminium foil. With the bulb pointed straight up and the cardboard and fabric on top I took a few photos.

Do you see anything interesting in the pictures attached?

Scott.

Scott wrote:

I am seriously thinking about using spruce for the yard, the boom and the battens. I am sure that this will make for a heavier rig, and more weight aloft.

Is there any other reason why I should not use epoxy laminated spars made from the stuff that is labeled 'Pine / Spruce / Fir' at the home improvement store?

Scott,

If you select stock with only small knots, and laminate battens from two pieces such that the run of the grain in each piece is a mirror image of the other (if you see what I mean), then you can get very stiff strong spars. Sure, a tube is the best for strength /weight ratio, putting all the material in exactly the right place, but apart from that, wooden battens will work fine for you. The same with the yard, but laminated from three or more pieces of small stock, so that any inadequacies in each piece are compensated by sounder material in the others. Given that, you needn't pay extra for prime, clear, straight grained boatbuilding timber.

Anonymous wrote:

Scott,
there is a trap which is easy to fall in  -  the paralysing fear of making something which isn’t perfect.

Relax, most cloths that are rot-proof and wind-tight will do. If Odyssey can be had at a reasonable price, then go for it. The sail will come out at about 7kg. It is on the stout side, but on the other hand, it will stand quite brutal handling and resist some chafe. Besides, it sews very well without pucking (at least on my machine).

Arne

(.. playing in the cheap, available and good enough league...)

I am OK with making something that is not perfect. I really enjoyed making my Puddle Duck out of only things that could be purchased at the local home improvement store and at the fabric and craft store here. I am honestly really impressed with how well some decorative polyester ribbon seems to work as a webbing bolt rope on that sail. It is fairly low stretch and strong enough to be to be 'good enough'.

What can be paralyzing on the S2 conversion is that I only have the budget to do everything once. If I purchase something that I think is good enough, and it is not, the whole project will need to be put on hold for maybe a year or so until I can purchase the right material.

I am absolutely looking for cheap, available and good enough. Just in case it is not totally obvious yet -- I am trying to find something less expensive than Odyssey that will do the job. I am waiting on a different 1-yard fabric piece to be delivered. I plan to pull on it, look at the fabric through a bright light, and guess at if it can be used as sail cloth.

While I am waiting I am also thinking about spars. I found a lamp post that seems to be strong enough and priced so that it will not eat up my entire boat budget for the year. But I am having a hard time with the pricing of aluminum alloy tube!

I am seriously thinking about using spruce for the yard, the boom and the battens. I am sure that this will make for a heavier rig, and more weight aloft.

Is there any other reason why I should not use epoxy laminated spars made from the stuff that is labeled 'Pine / Spruce / Fir' at the home improvement store?

Scott wrote:

I appreciate the spirited discussion on materials and sail construction. There is much to think about.

I got my order of POLYESTER RIPSTOP (DWR) - 2.6 OZ. I like the way it feels (for what that is worth) and it definitely sheds water very well. It seems less stretchy and stronger than other materials. I would say it is much less stretch than any nylon I have looked at and slightly less stretch than Odyssey.

Unfortunately, if I give it a little effort, I can blow air though it. It seems that a coating of Polyurethane or Acrylic or something to make the fabric air tight is a necessary feature. This fabric does not have a coating.

I will probably use this to make some bags. I can't imagine it is good to have air blowing through a sail.

It seems the supplier used straight scissors or a razor to cut the fabric. A hot knife or pinking shears would have been considerate. When I unfolded the fabric large parts of the weave came apart in a long thread.

It's not a lack of coating that should cause you to avoid this cloth. Try holding it up to a strong light - can you see pinhole-size leakage of light through it? If not, it's tightly woven enough. If it can be used for kites and tents, as the supplier claims, then it's airtight enough for a lightweight sail. It's similar to the cloth I used for my windvane, which is still strong (but faded, as it's red) after two full seasons of exposure to UV. 

Yes, you'd need a hot knife to work with it. Also, V69 thread will be too heavy. Use a 100% polyester thread intended for outdoor clothing and equipment, metric size 75, Tex size T-35.  On the construction, it's up to you whether you listen to Arne or to me; I'm just going to repeat that good construction methods are going to be essential to making a successful sail in a cloth this light. I would recommend a sailplan with a low yard angle  to decrease stresses around the peak and throat, too. Amiina's very lightweight split junk sail has a low yard angle. Weaverbird's sail, yard angle ~ 45˚, though made from heavy cloth, is designed to minimise the loadings on the parrels, and therefore also the loadings on the cloth will be lower than with  ~ 70˚ yard angle.

David wrote

No, one should not un-learn western sailmaking. Sailmaking is sailmaking, whatever the kind of sail. Bad practice is bad practice, whatever the kind of sail.

Okey, so the millions of Chinese got it all wrong during all those centuries  -  too bad for them.
Only problem; I think their sails made a lot of sense…