Graham, Colin,

would you mind to explain why you expect a fan-shaped top to sail better in strong winds?

Cheers,

Paul

Graham, I have sailed with a square top sail in 30+ knots of wind but the sail was not reefed. It handled well upwind, but downwind I was very aware of the danger of death rolls. I had that Laser going close to world record speeds. I never built any reefing system, although I did tie some of the lower battens together to see if it would still sail and it did fine, but it certainly was not in strong wind. I figured with a sail so small if I wanted to reef I could lean forward and tie some battens together. A system of lines to do that while sitting so close seemed unnecessary.  I have sailed the Laser in open ocean but not in stormy weather, although the sea state was not exactly small. I cannot say I have sailed in a seaway, or what exactly you would define as such, but the Catalina Channel is known for some very strong currents, and I was able to sail up the coast to the Point Fermin Lighthouse from Angels Gate with ease. I agree that a fan topped sail seems like it would handle being deeply reefed better and likely maintain more favorable characteristics. I think an important variable is how much shape is in the upper panels whilst that deeply reefed. Just as you mentioned a square top sail with a lot of camber in the upper panels would likely work well in light airs, but not in strong winds when reefed, so too may a fan top sail with lots of camber in the upper panels have undesirable characteristics in strong winds while reefed. It seems we are in agreeance that too much shape in the upper panels is a bad idea. Currently I believe it is best to have the top and lower panels entirely flat. I no longer view each panel as a tiny sail, instead I see one shape that I am trying to encourage to form in the sail by cutting camber in specific panels only.

Jan, that folding sailboat looks like a lot of fun. It is certainly easier to cut out a square junk sail, but I would argue that rigging one may be more difficult. I am curious as to why you used two yards. May I ask what the purpose of the second topmost one is? 

Colin, do you have experience in sailing with a deeply-reefed square-topped sail in strong winds, and perhaps also in something of a seaway?  Intuitively, I feel the fan-shaped topsail would be better in those conditions, but there is no doubt that junk-rig performance can confound expectations.  I also wonder about putting the most camber in the top of the sail. Once again, my experience would suggest that this might work well for light to moderate winds with  full sail hoisted, but not when the sail is deeply reefed in strong winds.

Here's a few more square top batten lug sails (old and new).

They all have the lifts,  sheeting and reefing systems which identify them as true Chinese junks, except for the last two which I have some doubts about. The second to last  appears to have sheeting on both the luff and leech side of the square panels and might trace its origin more to the "square sail". Not sure. The last one (Lores) I'm not sure about either.

The split one, third to last (with the blue sail and fold-away hull), fits the definition (well, my definition) of the Chinese junk and has been the subject of recent posts (Jan Cz).

Also, Amiina (another SJR) raced for a season with the top panel missing ...

Oh, and lets not forget Roger S's laserPanic (yet another SJR)

rather apposite to your own boat (another laser, with a square top batten lug sail)

Hello, my name is Colin Clayton!

After spending years making junk sails for a Laser at Cabrillo Beach, California and testing them in Hurricane Gulch I wish to share what I have learned as I believe it may be beneficial to other junk sailors.

I used to add camber into every panel of my junk sails, except the top panels, similarly to many junk sails that I see today. I have found that shape in the lower panels reduces the effectiveness of the sail. It seems that only panels located about 2/3rds up the sail should have camber added.

I used to add the most camber into the bottom panels and lessened the amount of added camber going up the sail. Once I reversed that it was a world of difference especially in regard to how high I could point into the wind.

I also tried many methods to attach the sail to the mast. The one that seemed to work best for me was also the most simple. An eye is placed at the luff end of each batten. Then a single line, beginning at a control cleat, is laced through the eye and around the mast for each batten then tied off at the yard. This made the sail very free, but still very much under control. It almost began to feel like I was flying a kite on a pole instead of wrangling a mechanical wing.

Fan top style junk rigs were all I made at first. One day, almost as a joke, I decided to make a rectangular one, fully expecting it to sail terribly. Surprisingly, it was much faster going upwind and felt more stable. I think there are benefits to a fan top style rig over a square top one, but if speed is your goal then a cambered square top is the answer.

Attached to the post are pictures of an earlier fan top sail with shape in the lower panels as well as a fan top sail with camber added only in the upper middle section. Finally, there is a picture of a square top sail that highlights the location of the shape added to the panels.

Here is a video showing how I rigged my Laser and another showing how to cut out the sail panels.

How To Make A Junk Sail (Part Two Rigging)

How To Make A Junk Sail (Part One Lofting)

Happy Sailing!