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Anke and I live aboard WAYWARD, and wrote about it's design and construction at

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Fair winds!

Dave and Anke
triloboats swirly gmail daughter com

Tuesday, December 13, 2011

Why I Love Junk Rig

What, me worry?

The junk rig or "Chinese lug rig" is easy to handle, very easy to reef, easy and inexpensive to build, easy to rig, has no complex hardware, requires no winches, is easy to maintain, involves very low rigging stresses, provides a low center of effort so requires less beam or depth of keel, and at least in my view, looks great!

-- Michael Kasten

Why We Love Junk Rig

The wind is up. Sail, too, but can be reefed in seconds. Sitting quietly, doing nothing, the boat sails itself. Almost.

JR looks complicated due to a lot of lines running every which way. But stress is dissipated wonderfully across the entire rig; JR sails were once made of woven grass mats! Masts are commonly free-standing and made of mere wood! In a day of high modulus ploycarbon sail cloth and rod stayed, aluminum alloy masts, this is barely conceivable. Yet the rig has been keeping the sea for thousands of years.

A Quick Run-Through

JR is a fully battened, standing lug (the sail is set on one side of the mast only) rig. As in western rigs, sheets haul and ease sail, but are attached along the leech at full length battens (rather than just the boom). A halyard raises and lowers the yard and attached sail. Topping lifts act as lazy jacks to gather the reefed sail. Parrels act in lieu of sail track and slides, keeping spars close to the mast. Downhauls get the sails down in any weather.

This arrangement allows control of the shape of the leech (and therefore sail draft) and avoids tack and clew downhauls. Sheets control the sail as it is reefed to any point. To reef, merely lower the halyard to the desired point (sheets go slack), make fast and trim in.

There's a slew of possible refinements, each of which add controls impossible in standard western rigs, but that's a deep dive.

Now, despite anecdotal evidence from the East where working Junks with tired sails have been observed to smoke Western racer cruisers, JR has a bad rep, especially to windward. Their abilities, we believe, have been somewhat lost in translation and are only recently beginning to correct. In brief, Asians used cotton which stretches (vs. low stretch synthetics).  Geometries that made the most of that ‘shaping’ (vs. those promoting docility). Controlled sail set for conditions (vs. elimination of twist). Each of these western approaches degrade performance, especially when sailing to windward.

(with Flat-Cut Sails)

Our Junk Rigs

So what do we do? Anke and I dumb ours down, of course.

Parallel battens for easy handling (that docile, inefficient geometry). Sheet and haulyard are the only running lines, all others are standing. Multiple sails allow us to adjust sail balance without extra control lines. Continuous running sheets (5 and 6 part) are simple haul / ease, and mechanically advantageous to handle (no expensive winches), but give up fine control of leech shape. Substantial battens drop the sails without downhauls (we do have to round up, a bit, to drop sail in high gale conditions, with sail between wind and mast and clip downhauls in for gale+ conditions). 

We thus keep line handling to a bare minimum. Sails are low-stretch, but shaped for lift.

A word on our unusual upper panel shape... it's essentially a flat cut Polynesian Crab Claw. When deep reefed, it retains great shape and drive, but can be flattened to reduce power in high winds. The deep hollow leech brings the CE inboard for reduced weather helm (eliminating sail centering lines). It was an experiment that worked out.

Summary of JR advantages (Robust, Fail-Safer, Simple, Easy, Cheap)

  • Robust (distributed stresses reduce likelihood of gear failure).

  • Low Center of Effort (quad sails spread wide and low).

  • Light booms (reduce danger of concussion). 

  • Jibes all standing with no problem.

  • Sails entirely handled from the cockpit via sheet and halyard.

  • Quick reefing (Let go halyard! BAM, BAM, BAM! Make fast! Trim Sheets! Done in 5 to 10 seconds!).

  • No tack or clew downhauls or reef nettles (AND no lurching about, wrestling bunts, tying nettles overhead).

  • Sail weathercocks without flogging (tamed by battens in all weather... easier on sail and nerves).

  • Can reef upward (raising booms for visibility, deck loads, tarps, laundry, etc.).

  • Can set masts free-standing, in tabernacles (for easy dropping / maintenance).

  • Lightly stayed, if at all (cheap, low windage, little to no 'shrieking rigging').

  • May spread more sail area (easy to handle, so ~10% more).

  • Few to no sail changes (all area in working set).

  • Can climb battens like ratlines.

  • Inexpensive to build and maintain (simple components, DIY sails).

Y'know... we’re not fanatic about JR, but we are fans. As a cruising rig for wild waters and a shoestring boat - the only kind I'll likely ever own…

Junk Rig keeps wooing us back.

1 comment:

  1. The 'Gurney Flaps' (GFs) I mention turn out to be a longer, more complicated story than I knew at the time of this writing.

    Controversy in a nutshell:

    JR gurney flaps are misnomers, bearing little resemblance to the real ones found useful in automobile design and trialed in aircraft wing design. They are much more like the drag flaps used to slow aircraft on landing.

    Proponents claim that they enhance (windward) performance, with various explanations as to why. Opponents argue that they induce drag (aerodynamically correct), so should not be used.

    JR GFs set aft of a sail's leech, in line with the sheets.

    Close-hauled they are nearly, but not quite in line with the sail's airfoil, causing drag (undesirable, on the wind).

    As the sheets are eased, their - and the GF's - angle to the sail increases toward 90deg, producing ever more drag (desirable well off the wind).

    I've seen a video (which, unfortunately, I cannot locate) in which a traditional Chinese junk was distinctly fitted with a JRGF.

    My hypothesis is that a trade-wind vessel might choose a JRGF, sacrificing occasional windward performance for enhanced downwind performance.

    Be aware that the benefits, if any, are hotly contested.

    Dave Z