Anonymous wrote:

Anonymous wrote:

I wouldn't use odyssey for a cruising boat. The photos attached show a sail made of odyssey3 in 2011 and under new ownership a year later.

Sorry, can't flip the 2011 picture right way up.

Downloading and zooming the pics I don't see any obvious tears in the sail. An alternative explanation for the difference in the pictures is: with wind and without wind.

Forget about western sailmaking in junkrigs

David,
Well, then I guess it is my turn to repeat that one should sort of un-learn western sailmaking when making a cambered panels junksail. The reason is that the load in the fabric is an order of magnitude lower than in western sails of the same sail area. This it had to be on the original Chinese sails, since the Chinese until recently did not have access to strong sail-material. To them the boltrope was probably not primarily to keep a shape in the sail, but to avoid ripping and destroying the whole thing.

But let’s say that I have misunderstood this. How come then that my sails don’t get distorted after several years of sailing? How can it be that Johanna was just as close-winded the day I sold her in 2014 as during the first sails in 2003? How can it be that her helm balance did not change over time as a result of the camber moving aft? And how can it be that my sails last quite well?
Could it be that my sails, with their stout webbing boltropes, and no fancy sailmaker craftsmanship in them, are good after all? I think so.
Practical sailing experience beats theories and words.

Arne

Johanna in 2014 with her new owner

Asmat,

Your photos clearly illustrate why I do not use, and strongly advocate against using  boltrope or webbing on the leech of a JR sail. When that sail was new, it is clear that the boltrope was just a little too tight, and the leech is hooking, just a little. When the sail has aged, the rope has stretched, and is no longer supporting the cloth, which has stretched and broken down. When two materials have different stretch characteristics, which then change as they age, it is impossible to get them to work together. Seatbelt webbing simply cannot be matched with common sailmaking cloths. This is not sailmaking; it is canvas work, where the finished item is rarely under the conditions of being tensioned and expected to take a pleasingly fair and well defined shape. I do not accept for one moment that a 3D JR sail panel needs this kind of canvasworker's approach, that Arne defends so eagerly.

I will say again, for what feels like the umpteenth time: the right way to construct a leech is the conventional sailmaker's way: firstly, to lay the cloths that make up the panel either parallel or perpendicular to the edge, within 5˚, and secondly, to finish the edge with a sailmaker's tabling about 50mm wide, either rolled (like a garment hem, turned in twice), or a separate piece of cloth, threadline parallel to that in the cloth of the panel, folded in half and sewn on over the edge). That is all that is needed, but a doubler, 200 - 300mm wide, added to the edge before the tabling, mitigates against breakdown of the cloth in the long term.

In the days of sailmaking in natural fibre, it was a very skilled job to rope a sail. The boltrope had to be just a little bit tight on the luff and foot (and the head of a gaff sail), but that was OK because the tension, and therefore the stretch, on those edges was adjusted with the halyard and outhauls. Boltrope was never applied to the leech, for the reasons given in my first paragraph (except for storm sails, when set was secondary to overall strength). In a JR sail, we do not have control over the tension in the luff and leech, so we cannot control stretch.

Just because traditional Chinese sailmakers used a boltrope does not make it right. A look at old photos of junks rarely impresses one with the set of the sails. Did they look at Western sailmaking practice and copy it without understanding? I don't know, but I suspect so. Their sails used to be made from rattan, but when they started using western canvas, their old methods would not apply. So, what to copy? The visiting tea clippers etc.

I am an eager defender of the use of a strong boltrope around junksails, at least when the sails have been cut with baggy panels. In these sail (unlike in flat sails) all the vertical loads move out from the sailcloth to the bolrope. The load is highest at the leech, where the sheet is pulling.

This is how the Chinese sailors got away with fairly weak sailcloth: The yard, battens and boom, connected with boltropes, formed the framework. The sailcloth was just there to catch the wind and deliver the force to the nearest edge of each batten panel.

This only dawned to me when reading an article of Vincent Reddish in Practical Boat Owner (reprinted in JRA NL 22) a long time ago.
I therefore conclude that a strong boltrope is an absolute must if the sail is made with baggy panels. On the other hand, with this in place, either in the shape of a handstitched on rope, or a machine-sewn webbing, there is no need for strengthening patches in the sails’ corners. Keep pulling on the sail via the battens and boltropes, and the sailcloth will see little stress.
The photo below shows the peak corner of my Ingeborg’s sail. The hoop ensures that the load is taken by the boltrope, not the cloth. I have used this method on a number of sails now without signs of overstressing the cloth.

Arne

PS: As for UV-resistance and Odyssey, I cannot tell, since Stavanger at 59°N has less problems with UV-radiation. Still, I now use sail cover over Ingeborg’s sail, just to be sure.

I'm afraid I'd have to agree with Asmat, at least from a New Zealand perspective.  Quite a few of us have found that the fabric doesn't seem to like the sun very much and, in my own opinion, will start to come apart if only moderately loaded.  I wouldn't use it again, but Arne seems to have been very happy with it.  Although I didn't feel that my sail failed because of sun damage, considering Arne's success, it is the only sensible conclusion to draw.