Karlis Kalnins wrote:

"Dave Mallory (a San Fransisco Bay Area friend) has worked out my favorite profile for the Chinese lug sail. He used it for years on his converted 36-foot lifeboat Kokoro, and I adapted it for our 46-foot schooner Yankee Belle."

(Derek Van Loan, page 11, 2007 ed) 

Hi Karlis,

I've been meaning to write and ask to what extent the Van Loans (possibly including Derek's brother) 'adapted' the sails. Whether it was merely to resize to fit the larger vessel(s), or whether he significantly modified the 'formula'. In the former case, I'd think it would be a Mallory Rig, whereas in the latter, it is arguably Mallory/Van Loan.

This came up in the Junk Rig Glossary, and I hope to get that chased down before too long!

Dave Z

Dave,

"Obsession with perfection has always made a fine anchor."That is a very useful reminder, I will pin it up! 

Of course, the the fact (or belief) that the Chinese didn't shift their sails back and forth, does not prevent us from doing it. It is all about finding the easiest way which works with a minimum of fuss.

Arne

PS: My point with arguing for powerful rudders is not just to handle the turning moment of the sails, but also to handle big offshore waves from behind. That is a bigger challenge, so if one elects to just balance out the rig instead of fitting a serious rudder, one has only solved one of two problems. Well and fine for inshore sailing, though.

Arne Kverneland wrote:

I can see the point with being able to shift the sail forward to balance the rig, but only as a plan B. I haven’t seen any evidence that the Chinese did or do this to their sails.

Instead, they use proper rudders.  I bet that that most Chinese sailors of real junks would have declared the rudders of many western sailboats (like Tystie and Mallimac) to be inferior. The rudders of these boats are not small, but if the Chinese had their will, they would fit them in a way that let them lower them below the heel of the keel. In deeper water, well away from the thick boundary layer created by the long keel or hull, the rudder is a lot more powerful. Look at these two rudders. They are quite big, compared to those on fin-keeled boats. Still they must be this size to be effective when working in the thick boundary layer. I know that Paul J Thompson is about to make  (or have finished) a new rudder for La Chica. This will be moved aft and away from the keel. It will be interesting to hear his experience with the new one.

As for the AS29, my guess is that if this boat type steers well downwind with a gaff mainsail, it will steer even better with a junk sail, even without shifting the sail back and forth. The key to that is the ability to ease the sheet of, or completely furl the mizzen.

Try not to anticipate all sorts of problems; things may well end well...

Arne

PS: And again, carrying no more sail downwind than when close-hauled, will in most cases ensure easy steering... 

Hi Arne (et al),

You could be right the Chinese not squaring away before the wind, but I'm not sure I'd rule it out, either. Certainly, may of their foresails have balances ranging from large to near half. These would be in a good position for heavy weather, balanced pull.

I also agree that good sized rudders (and aft, lateral resistence in general) make for a steady sleigh ride.

The AS29, however, having neither keel nor skeg turns on a dime. Being this nimble makes her great at threading shoals, but the hull doesn't resist rounding up as stongly as others. What's more, the designed rudder is on the small side and shallow, only partially compensated by the plate along its lower edge. It may well be that, beyond a given wind strength, it doesn't steer that well downwind under its original rig. Ours certainly had its upper limits under HM JR.

We modified ours with a large (many would say very large), kickup, outboard rudder that extends well below the hull. It gave very positive control under most conditions. However, running or broad reaching in gales under deep reefed foresail (HM, two panel 'triangle'), gusts from 50 kts or so would round us up, willy nilly. We learned to leave a little extra room for sudden U-turns to windward in these conditions!

This led us - using the same rudder scheme - to try the smaller area, deep-cut crab claw uppers you see on SLACKTIDE (our posting image),  which worked out great... zero round-ups to date.

Not a straight-up comparison, however, as the barge has more hull LR than the sharpie, so tracks better (but consequent slower turns / larger turn radius... the AS never missed a tack, while the barge needs to be handled just right).

One simple and traditional solution (I've heard attributed to the Chinese) is to provide aft resistance via a drogue.

So, personally, I'd lean toward easy fixes to excessive weather helm at the planning stages, then learn to handle what's leftover when the conversion is underway.

But I take your point, Arne. Over anticipation of problems can be overdone! Solutions lie along the entire spectrum, and sailors have been figuring out how to make their vessels move since the first log! So yes, our best shot is a fine thing, but better to get out there. Obsession with perfection has always made a fine anchor.

Dave Z

Dave Zeiger wrote:

Graham Cox wrote:

 If balance is an issue, you can use twin mast lifts and swing the sail across the mast with ease, effectively turning the sail into a squaresail or flat-cut spinnaker.

Graham, am I picturing this right, that you're suggesting a fwd and aft mast lift, plus a boom hauling parrel? To square off, you ease the boom hauling parrel, allowing the sail to rotate around its slingpoint? Hmm... and also running luff parel(s) to tidy up? In other words, the Reddish/Sunbird, etc approach applied to an HM (parallelogram) sail?

Canting the lower sail fwd would mean relatively more sail aloft than alow. The CE of the upper sail would remain well outboard, while the CE of the lower sail would move inboard. Seems like that might generate yawing vector (forward and down from high on a fwd quarter)?

Could you point me to anyone who's tried this?... we've considered it for various reasons, but chickened out, and I'm curious about handling effects (if noticeable).

The Mallory (Van Loan) planform might be a better candidate, in this case (assuming yawing problems), as its slingpoint is well aft of the mast, allowing plenty of room to haul it forward (no cant), compared to the HM planform. The sail position could then be adjusted without canting.

The twin mast lifts are both at the front of the boom, one on either side of the sail, instead of one lift that goes under the boom and around the mast.  Sunbird often rig their boats this way.  A single lift tends to hold the bundle in to the mast when you have some panels reefed.  With the twin lifts, you rely on a long boom parrel, like the batten parrels to hold the boom against the mast when the sail is to leeward.  Standard PJR type topping lifts hold up the back of the boom or reefed bundle.  When you ease the boom hauling parrel, the bottom of the sail swings forward.  It helps if you have at least 10 degrees of rise in the boom, 15 would be even better, but it doesn't matter , even if the boom ends up beyond the horizontal it will merely look a bit skewed.  Some people, including David Tyler, (when he had a junk sail) also haul the boom forward, rather than relying on gravity.  David used this system to balance Tystie downwind during many miles of ocean passages and others have done so too.  I don't, both because my balance is reasonably good even when driving hard and also because I have fixed luff parrels on my lower three battens to stop negative batten stagger in my cambered sail.  If I didn't have the fixed luff parrels, I would probably do it though when driving hard downwind.  I think I'd adjust the sail while reefing, which I do beam on to the wind with the sail feathered, as it would be effortless, instead of trying to drag the sail across, especially when it was to windward of the mast.  I am told that swinging the sail across like this significantly reduces weather helm.  I think you might see pictures of Tystie sailing like this in David's photo albums or back-issues of the JRA magazine.  You can also see a photo of Peter Manning's Malliemac sailing like this on page 13 of issue number 62, though it is in sheltered waters.

Graham Cox wrote:

 If balance is an issue, you can use twin mast lifts and swing the sail across the mast with ease, effectively turning the sail into a squaresail or flat-cut spinnaker.

Canting the lower sail fwd would mean relatively more sail aloft than alow. The CE of the upper sail would remain well outboard, while the CE of the lower sail would move inboard. Seems like that might generate yawing vector (forward and down from high on a fwd quarter)?

Could you point me to anyone who's tried this?... we've considered it for various reasons, but chickened out, and I'm curious about handling effects (if noticeable).

The Mallory (Van Loan) planform might be a better candidate, in this case (assuming yawing problems), as its slingpoint is well aft of the mast, allowing plenty of room to haul it forward (no cant), compared to the HM planform. The sail position could then be adjusted without canting.