Jan Cz.: “… look at this video at minute 5:12. Isn't this Pugwash?”
It does look like a Portland Pudgy, Jan, though it is not Pugwash.
Braddock: ”I am wondering what sail material would be recommended for a small dinghy? “
I’m not qualified to advise, but no-one else has, so here is what I did. A sail I made for a small boat some years ago, was made from cloth taken from an old nylon spinnaker which I am guessing was about 65 – 70 gsm. It was not stretchy, but lovely and soft, and I did not realise at the time how good it was. I wish I knew where I could get more of that stuff. Since then, I made a couple of 5-panel Johanna dinghy sails using Maxilite 150 which is about 70 gsm. It seems to be some kind of polyester, I am not sure what it is, a bit stiff and crinkly, but fairly light and any amount strong enough for a dinghy, I think. [edit: turns out it's impregnated nylon] Although you could make a small junk sail out of almost anything, I think it is a shame to invest time and care into stuff like polytarp when a few metres of something decent is not really costly.
“I have a Bernina sewing machine, so ideally the material would be light enough so that I can still sew the webbing”. My sewing machine is a little bit “heavy duty” and has no problem sewing webbing, but I was unable to go out and buy any at the time so I used a strip of folded-double, heavier dacron sail cloth to make a kind of tabling for the luff and leech. It was just what I had available. I thought it would be strong and non-stretch enough for a small sail which will not see heavy duty use or heavy weather – or lengthy exposure to sunlight. Here is a trial sample I did. This one was folded 1/3 - 2/3.
If you feel that webbing will be difficult to sew or perhaps more than needed for a tiny sail, you can make your own dacron doubled tape. It is easy, with a hot-knife and a 1m steel rule, to cut some heavier dacron or other non-stretch cloth into strips, fold it longitudinally in half, and make the crease by stroking heavily with the back edge of a pair of steel scissors, or ruler, or something similar. I thought this would be good enough for the luff, leech, head and foot of a sail for a small dinghy. Your little pudgy sail won’t carry heavy loads or see a lot of heavy-duty use. You will need some narrow webbing for tabs and loops and you can get light stuff from a sewing materials shop, but I think your luff and leech ought to be non-stretchable. Whether this doubled heavier sail cloth proves to be a suitable substitute for webbing on a tiny sail I do not know yet, but I can’t see why not, and I am supposing it would be a little bit easier for a light-duty sewing machine, if sewing webbing is a concern to you.
There is not really a lot of advantage in a junk sail for such a small boat, in my opinion, but it is an excellent project, and making a complete miniature junk sail can give a great deal of satisfaction and learning. If you closely follow Arne’s method and order of procedure, you will find the whole process quite quick and enjoyable – and the result will be very good, as many other people have already found.