Rusty the Junk - The Rig

Rusty is a 2 masted junk Traditional Chinese rigged schoonerMore than 1 mast and the foremost mast is not the tallest. We spent a lot of time discussing various rigs.
Among the possibilities were -

• Bermudan Main sail is triangular Sloop Only 1 mast
• Bermudan Ketch 2 masts and the foremost mast is tallest.
• Staysail The sail between the masts is a staysail not a main sail Schooner
• Freedom Unstayed carbon-fibre masts, with wrap around sails
• Junk rigged Schooner

There are obviously lots more, but these are the only ones we seriously considered. See here for a comparison of these types.

We discussed these rigs for a long time and consulted with our many sailing acquaintances and friends. The conclusion was that the Junk rig offered the lowest tech solution and was therefore the cheapest and easiest to maintain, and, with the addition of a good winching system, offered the easiest sail handling. In addition to this it is the one that has been tried and tested for the longest, on a variety of boat shapes and in a variety of conditions.

We obtained a copy of the Junk bible (at least in the west) Hasler and McLeod's Practical Junk Rig. This wonderful book provides a lot of the theory of junk rigs, various possible mast and sail arrangements, and best of all a complete how-to of designing and manufacturing your own rig. With this in hand, and the 3D modelling package, we were away.

For a long time we tried to make a traditional Chinese 3 masted schooner on Rusty's hull, but we just couldn't find a way to sheet the mizzen The aftmost sail. sail. Eventually we gave in and settled for a 2 masted schooner.

We started from the ketch sail layout provided by Bruce Roberts in the set of plans for Rusty. We increased the sail area, because of the ease with which junks can be reefed. We took the Lead The amount by which the Centre of Effort of the sails is ahead of the Centre of Resistance of the hull. specified by Bruce Roberts and the Centre of Lateral Resistance The point on the hull where the sea pushes against it. provided by the model, together with the book, to get the desired Centre of Effort The point on the sails, where the wind pushes/pulls it. The higher it is, the more the boat leans over. of the new rig. We then adjusted mast positions and sail sizes until it all fitted together - judicious use of a spread sheet helped here.

Having done all the design and drawing, and seen what it looked like when we rendered the model, we started to turn it into reality.

The shoes The cup holding the foot of the mast. Strongly welded to the hull. for the masts were made of steel, essentially a tapered cube with drain holes and a lot of strengthening. They also had tangs extending up two sides so that we could put a retaining bolt right through both tangs and the mast. This is mostly to remove any chance of the masts jumping out of the shoes in very heavy weather.

We made partners The support and strengthening for the mast where it passes through the deck. at deck level. In order to simplify our task we actually made straight sided partners in the form of octagons, and welded these into place, with quite a lot of strengthening, since this is where the vast majority of the stress in a junk rig comes.

The relative positioning of the shoes and the partners was complicated by the requirement for each mast to lean forward - 1° in the case of the main mast and 5° for the fore mast. We did this by making mockups of the masts in plywood set at right angles, then a lot of fiddling with plumb line, level and protractor.

The masts need to be tapered and flexible. We considered several different materials, including -

	Carbon Fibre	The ultimate hi-tech solution, unbelievably expensive. 10years ago 1 mast was quoted at £12000!
	Tapered Aluminium	Flag poles, street lights etc. A good solution, but surprisingly difficult to source in the UK.
	Hollow wood	A good solution, recommended by Hasler and McLeod. We found a mast maker in The Netherlands who quoted a good price. But still quite expensive.
	Solid Wood	Telegraph poles etc. The traditional Chinese solution. We found Calders and Grandidge, in Boston, Lincolnshire, who import and process the vast majority of poles in the UK. Also an extremely good price.

We went ahead and ordered 2 telegraph poles from Calders and Grandidge.

They were quite used to people coming to them and asking for masts for boats. We gave them the required dimensions and they promised to look out for appropriate poles. Some time later we went out into deepest fen land to make a final selection from the short-list that they had chosen.

It was an amazing site. Thousands of poles everywhere. Two of the biggest lathes you have ever seen. Pits for treating the poles. You could smell the creosote A well known black wood preservative. about 2 miles away. We were given a choice of treatment, creosote, CCA Another wood preservative (this time green) and quite poisonous. Made up of Copper, Chromium and Arsenic compounds. or untreated. Unsurprisingly we chose untreated. CCA is environmentally unfriendly and is thought to dry the wood out too much, and creosote comes off on everything forever. We coated them in raw linseed oil to preserve them. They organised to drop them off for us on a delivery that was going close, which meant that the delivery charges were kept low. All in all Calders and Grandidge were extremely helpful and we would unreservedly recommend them to anyone looking for poles.

When we received the poles we set them up on rests, and proceeded to dress them as masts. This required them to be straight tapered, from deck level up to the head and from deck level down to the foot. Thus they ended up as elongated barrel shapes with the widest part at deck level. The foot had to be shaped to match the shoe welded to the hull for each mast and the head shaped to take the mast cap that had been fabricated for each mast. In addition each mast was grooved on both sides, for cabling to lights and aerials, and for lightning conductors. These grooves were covered and made smooth once the wires had been laid. It was a lot of work but none of it impossibly complex.

The tapering was quite a big operation. Fortunately a carpenter friend was intrigued by the job, and did most of it for us. The technique starts by marking the desired circles on the ends of the poles. The heart wood should be inside this circle, but doesn't have to be at the centre. Then draw a square around the circle. The pole was planed down to each side of the square in a flat slope. Then the corners of this square were planed off, to make an octagon, then the corners of the octagon were planed off, etc etc until we were back to a rounded shape.

For the mast feet, we cast fibre glass plugs of the mast shoes and then made female moulds from them, which we used to check the actual feet of the masts. The shoe for the main mast had been welded on off centre and slightly rotated. It's possible that the welder was hungover or stoned that day. This had to be corrected for by modifying the foot of the mast. Much easier to get the shoe right to start with.

Once the masts were complete, we rigged them with a single halyard each, so that we could get up them later, and had them craned into place. The operation went surprisingly smoothly apart from the tangs on the foremast. We did the foremast first and had to force it between the tangs in the feet, because we hadn't made the cut-outs in the mast wide enough. Seeing this a lad was dispatched to the main mast with a chisel, and rapidly made the cut-outs on that one bigger. It dropped in like a dream.

Still to come -
Rigging a Junk - We've only just started on this, and already the details of the design have changed several times. Hint - Work out the rigging warrant A complete list of all the ropes needed for the rig. Including diameter, length, splices, thimbles, shackles, pulleys etc. in advance. The sheer amount of rope needed is mind boggling. We saved quite a lot of money by buying full reels of 8mm and 10mm. Yes, we have used all of it.

References
Voyaging on a Small Income by Annie Hill
The Junk Rig Association