Make this swinging yard concept simple to the extreme by doing away with the challenges with the lee pod and you might get something like this. Unlike its inspiration the crab claw, it is still reefable, and avoids a tilting mast. I don’t recall seeing any proas with a rig like this; I wonder why not?

To shunt, there would only be two steps: 1)pull on the line to move the yard to the other bow 2)sheet in

This is an interesting thread.  I am a HUGE fan of the Te Pookie wishbone rig.  But I wonder if there’s an easier way.

Here’s a thought experiment.  What if you had a Brown style rig with no main, and instead of two jibs that you raise and lower when you shunt, there’s just one jib and its tack is attached to a track running from bow to bow.  Now to shunt you release the old sheet, drag the tack of the jib over to the new side, and sheet in the new sheet.  Interplay between the track position and halyard could be used to adjust the location of the center of effort as needed for reefs, point of sail, etc. 

No tilty masts.  No other spars.  Hell, the mast could just be a tube.

Or is this just Skip Johnson’s set up without a boom?

Chris,

the big jib would need 2 things addressed.  head stay tension and optimum sheeting for various points of sail.  If you don’t mind a boom flying around on the shunts, the sheeting gets easier 😉.  A pair of furlers would allow permanent head stay tension, though the shape of a partially rolled up jib suffers (reefing).

Tom

Yup, head stay tension might be an issue.  John Harris needs a winch to get his flying jib as tight as it needs to be.  But the track that the clew of the jib travels on will provide some mechanical advantage—the luff tightens as the clew gets closer to the bow.  A two part traveler system for the clew track could be 2:1 for shunting and 8:1 for tightening the luff.

As for sheeting angle, you could use a sheet, placed for upwind work, plus a barber hauler that sheets from the lee tip of the pod to shift gears downwind.

Just a thought.

Chris

On the subject of shunting and prompted by this thread, I’ve just posted a an animation of an idea I had a few years ago at http://www.youtube.com/watch?v=nF6xC2rUU9w&feature=youtu.be  I hope it may be of interest. It’s a shroud system which helps with shunting a crab claw type rig.

Cheers,

Mal.

Mal,
That looks really great! I really like that the endless shunting line appears to move both the heel of the rig and tilt the mast at the same time; am I seeing that correctly? Thanks very much for posting that.

Yes, that is correct. The movement of the mast and luff spar is locked together by a kind of geared pantograph due to the fore and aft shrouds. An important factor is the ratio of the distance between the chain plates (Lc) and the length of the spreader (Ls), which controls the gearing:

If LC/Ls = 2, the heel of the rig wilL travel in a (more or less) straight line between the bows.

If Lc/Ls > 2, the heel of the rig wilL travel in a downward elliptical arc between the bows.

If Lc/Ls < 2, the heel of the rig wilL travel in an upward elliptical arc between the bows.

Changing the gearing can be useful if you need the heel of the rig to clear a cabin top, for example, during the shunt.

A couple of images of the model I built to test this rig are attached.

Cheers,

Mal.

Brainstorm! Rather than make a new thread I’ll keep my ideas here as they are related.

What if a lug sail of sorts was fore and aft symmetrical with the yard at 50% but had a movable parrel on the boom; would this allow shunting? The moveable parrel ensures the sheet will be lightly loaded at all times to maintain control of the sail.

This seems too simple; perhaps it would take some refining to get it to be as efficient as user friendly as it is simple.

Brainstorm #2 Chinese Junk set up to operate like a Bolger/Ayrs rig but with the last panel or two being present in duplicate: one set for each tack so that the normal chinese junk sailplan profile can be attained on either tack and the mast always is on the windward side. When one yard and top panel is hoisted, the other is down in a lazy jack where the horizontal panels meet the slanted panels… so the bottom 60-70% of the sail area is used on both tacks and has symmetrical camber panels

Adam,

You’re 87.4% or thereabouts down the road to Slieve’s Split junk rig with the mast at the 35% back from the luff position 😉

There’s reference to it over on Johannes’s box proa thread.

That’s actually the rig I’m going to try with an unstayed mast stepped as far to leeward as possible on the Vaka/cockpit area, hopefully betting the balance to where I can leave both rudders down all the time and achieve decent balance.

That is one VERY cool rig Mal.

Tom

Tom, thanks for the reference to the split junk; it looks like a rig worth experimenting with and I especially like how simple it is.

The simplicity and the ease of reefing is what I’ve always loved about the junk.  Since they started cambering panels, the windward ability seems to be acceptable as well.  Down wind there is no sail that is better behaved.  As to speed, check this out.

http://www.youtube.com/watch?v=h_ILYfWTEbk

The VERY cool thing about the split junk is you can get 1/3 of the area forward of the mast similar to a Baelstron rig without the High CE.  I’m guessing the lateral placement of the CE will be reasonably close to the mast as well.  Put far enough to windward,  this you gives nearly neutral helm on all points of sail, meaning I can leave both rudders down all the time.  This would (1) greatly simplify shunting.  Simply sheet the sail over.  (2) the lateral load on the rudder(s) would only be 50% of a single foil, meaning they can be smaller/shallower/less beefy.  A lee-board would essentially be unnecessary.

That’s my theory anyway, for what it’s worth 😉

Tom

Luomanen - 18 June 2012 02:18 PM

What if you had a Brown style rig with no main, and instead of two jibs that you raise and lower when you shunt, there’s just one jib and its tack is attached to a track running from bow to bow. 

Let’s cross-pollinate this idea with a gaff again; sort of like what started this thread. The jib portion is lead around the back of the mast during shunts. The bottom of the sail is tensioned onto a wishbone boom which is tensioned to the base of the mast. You end up with a rig that weathercocks yet is always on the leeward side of the mast and also has balanced forces for lighter sheet loads. The lack of a slot might give this sail the performance nod over the aero rig.