TWO MORE STRINGS OF MASTER SAILPLANS

I have spent the tail end of the Stavanger winter with drawing up two separate strings of master sailplans.

Originally, in 2014 there was the 10-sail string with Johanna 70 master sailplans. These sails with 70° yard angle have a shortcoming in common: Maximum mast balance ends up at around 17% with the halyard slingpoint at the 55% position.

These two new strings  of the Johanna 65 and Johanna 60 master sails will let one find and use sailplans with anything from 12 to about 26% mast balance.

I mainly did this to speed up my own design work, but I hope it will be helpful to some of you as well.

The files can be found on my page (The Junk Rig Association - Arne Kverneland) in the right column under MASTER SAILPLANS, or by clicking on these shortlinks:

• ·         Ten Johanna 70 Master sailplans: https://tinyurl.com/39hdktu9
• ·         Ten Johanna 65 Master sailplans: https://tinyurl.com/yztmjstm
• ·         Ten Johanna 60 Master sailplans: https://tinyurl.com/mr7weaj6

Cheers,
Arne

Ketil Greve showing off his Johanna 60 type sail on his Boudicca.
Plenty of mast balance, around 21-22%...

(Full size photos in the album, Photo section 7)

Sailcloth is cloth that is conceived, designed and manufactured specifically for making sails but one of the wonderful things about junkies is that we make sails out of all sorts of things from cheap tarpaulins to hot-air-balloon fabric and even “real” sailcloth. I think using the term sailcloth in a junk write-up isn’t quite right. Although once you’ve chosen a certain fabric to make your sail it does become your sailcloth. 

The word sailcloth has been in widespread use for many years and is in the English dictionary. It covers every sort of sail-making material. The Wiki description just about sums it up: Sailcloth is cloth used to make sails. It can be made of a variety of materials, including natural fibers such as flax, hemp, or cotton in various forms of sail canvas, and synthetic fibers such as nylon, polyester, aramids, and carbon fibers in various woven, spun, and molded textiles. Wikipedia

Graeme is right about the Norwegian term «seilduk». Btw. “duk” used alone is often used about table-cloth. As for “duck”; I frequently find it in books written by fellow Americans, Howard Chappelle and Bill Atkins (written about 100 years ago).

Another thing from that Chapter 5:
I write about the barrel cut method as if it were ‘meat and potatoes’. In fact, the method has sometimes been debated as to if or how it works. After all, asking a perfectly flat piece of  canvas to take a 3-dimensional, baggy shape, is quite something. That is why I nailed up a test panel before making my first cambered panel sail (NL 30).

For many years it was thought (by me as well) that it was the softness of the fabric which saved the day. Only a couple of years ago did it slowly dawn to me that this probably was not the case.

The fact is that the warp of the fabric is running parallel with the battens, so will not permit much horizontal stretch. Then, by looking more closely at a number of photos of Ingeborg’s sail, taken at right angle, I could spot a small but noticeable hollow at luff and leech. I had not reckoned with the extra length needed along the middle of the panel to make that camber. The sail sorted this out, all by itself.
This both gave a nice and even camber, plus that it prevented any hooked leech to develop  -  just like that  -   by accident! If I had made a gaff sail of that size, with that webbing at the leech, it surely would have ended with a hooked leech.

As it is, I feel no need to add Bermudan-style battens between the JR battens.

Arne

(Full size diagram at Member’s album, Arne’s sketches, section 7)

Yes, and is my sail made of polyester, dacron or Terylene?