China Moon was designed and built as a seaworthy ocean cruising home for short handed sailing. The unusual double junk rig provides for safe and easy handling. Sails can be hoisted and reefed from inside the cuddy without getting wet. Hinged carbon fibre battens give the sail a good shape. As well as her superb off wind performance she also sails well to windward and tacks easily,

Construction is marine grade Okume plywood. Epoxy and glass sheathed on the outside and epoxy coated on the inside. The hull, deck and cabins are foam insulated with an inner skin of plywood. This keeps China Moon cool in the tropics and warm and dry in cold weather. All windows, hatches and bubbles are double glazed.

China Moon has low aspect ratio keels with thick fibreglass base to enable her to dry out on uneven bottoms. The keels also protect the hulls from damage. The rudders are skeg hung and semi balanced.

China Moon was built in South Africa in 2003 and has since cruised to Brazil, Argentina, Patagonia, Magellan Straights, Beagle channel, Cape Horn, Antarctic, South Georgia and across the Southern ocean to Cape Town.  China Moon has sailed up to the Chesapeake via Brazil, Caribbean and Bermuda. Recently across the Tasman Sea to New Zealand. Very seaworthy ocean cruising home.

She is very easily driven and slipped along nicely with the articulating battens giving the sail a nice shape. The log was not calibrated but the estimated speed was about 3 knots to windward in a Force 3 and tacking through 100°. There was noticeable leeway, but not excessive. 

As soon as the wind picked up to a Force 4 she seemed much happier with very little leeway and was doing about 5 knots. The strongest the wind got up to was the bottom of Force 5 and she was then sailing at about 6 knots and tacking through 100 – 110° with no problems. There was a firm but not excessive weather helm. 

A close reach was her fastest point of sailing with speeds up to 8 knots 60° off the wind. With the wind right on the beam in a Force 4 she was sailing at 5 – 6 knots.

Both sails were pulling well but probably not at their most efficient, as the windward sail was feathered a bit and the leeward one was not in clean air. With the wind abaft the beam both sails were working well and once the wind was on the quarter she more or less steered herself. Sailing at about 4 – 5 knots in a force 3 – 4 wind the sea was flat, so of course the ride was very smooth.

The next two sails had up to Force 8 gusts, so it was not easy to analyse the performance. 

The 10 people aboard must have weighed in at  over half a ton and although she seemed a bit  slower it did not make that much difference.  The third sail ended up with several of the bat ten joints broken and a couple of the batten tubes bent, as well as flaring of the tubes ends at the joints, so obviously the battens were too weak.  I was loath to give up the articulating battens as they give the sail such a good shape and I am sure that a flat sail would ruin China Moon’s windward performance. I have now made carbon fibre battens using the old alloy 38mm OD x 1.6 mm wall tubes. My original joints were of white oak with a 3° taper on each of the cone ends. I have made  the new external joints out of 50mm OD x 3mm wall plastic pipe with a heavy layup of unidirectional carbon and plenty of glass and carbon going around the tube, it was not a cheap arrangement, but with 18’ long

The 26’ masts are hollow Douglas Fir and 8” OD at the partners. They are quite stiff and there seems to be little bend. They are mounted in tabernacles and quite easy to lift up, using the big rope winch on the centre deck.

China Moon swallowed 10 people sailing her without being the least bit crowded. 

The engine in the one hull works fine and she is very easy to steer going ahead, although going astern and manoeuvring in a marina is very difficult, especially if there is any wind, but with a 23’ beam I could never afford a marina again. 

The plan is to finish the essentials such as the self steering gear and a bit of electricity, then sail to Brazil via St Helena and spend several months in Brazil finishing China Moon off, before heading south to Argentina.

If any other members are planning on putting a junk rig on a cat then I hope they will be encouraged by my efforts — it does seem to work. I would say that two important aspects are keeping the masts well apart. (The centre of each mast is 18’8” apart) and having some shape in the sail. 

Progress Report December 2003

China Moon made a good passage to Brazil via St. Helena and later headed south to Patagonia, but it was decided not to continue to the South Shetlands as originally planned until the self steering is working better, so we are headed north back to Jacare in Brazil.

On passage we broke new ground by going up the Rio Negro to Viedma and were told that we were the first yacht that anyone could remember having paid them a visit. 

Apart from some small problems China Moon is proving herself to be a very able vessel. I am still learning how to get the best out of her. She sails very well to windward, a bit sluggish in a Force 2 but once the wind gets to a Force 3 she starts to move. The stronger the wind the better she goes. In a Force 4 – 5 she will be doing 5.5 to 6 knots and tacks through 100° (in a smooth sea) and 6 to 7 knots in a Force 6, there is little leeway. She sails much better to windward than I had expected. I’m sure the articulating battens account for much of this. The carbon fibre battens are holding up well with no sign yet that they will break, and we have been out in some quite strong winds. There is some interference between the sails on a reach but it is not a problem as it’s a fast point of sailing anyway. Downwind China Moon is a dream with the sails “wing & wong” she will steer herself. 

China Moon was designed to be a comfortable cruising Catamaran to be used for long voyages to remote cruising grounds. Fitting a junk rig on the boat was a major consideration. Having read about the successful junk rigged catamaran ‘Dragon Wings’, designed and built by Gary Lepak, I felt it feasible to design my own boat.

China Moon was built in South Africa over a period of 3 years. South Africa was chosen as a country with good access to materials, inexpensive and with a good climate, it proved to be a wise choice.

I used a hard chine design program called ‘Plyboats’. It ran in DOS and was very simple but it gave all the design outputs of displacement, centre of buoyancy, centre of lateral resistance and expanded offset tables for the panels.

• The hulls were dory shaped with flaring topsides and the hulls were built in two halfs.
• The lower half was built of 12mm plywood sides on 30mm stringers, over bulkheads, with polystyrene foam between the stringers and an inner layer of 4mm plywood.
• The bottom was a layer of 12mm plywood.
• The lower hulls were built upside down and then rolled over.
• The upper hull was then built on top with bulkheads, stringers, foam and 9mm plywood on the outside and 4mm plywood on the inside.
• The cabin and deck were built the same way but with 6mm plywood on the outside.
• The inside was completely coated with several coats of epoxy and then varnish or paint.
• The outside of the boat was sheathed in glass and epoxy before painting.
• The low aspect ratio keels are 10 feet long and  18” deep, built of plywood.
• The keels are hollow and form the diesel tanks, holding 175 litres each.

As launched there was no cuddy over the front of the cockpit, but the early cruise to Patagonia revealed how exposed the cockpit was and the addition of the cuddy made a huge difference to the shelter in the cockpit.

An 8′ dinghy lives in davits behind the after beam, which makes launching extremely easy. On passage the dinghy is stowed on the centre deck, just forward of the cuddy.

China Moon was originally launched with a 27HP Yanmar 3GM30 saildrive in the Starboard hull. This proved completely adequate, as long as not needing to manoeuvre in tight places with any wind blowing.

The new owner of China Moon subsequently (in 2010) replaced the engine with Yanmar YM30 saildrives in each hull, making the boat very manoeuvrable. The engines have 2 bladed folding propellers.

A 1:12 scale model was built of China Moon to test the balance of the rig in relation to the hull, rudder and keel. It was found that because multihulls hardly heel the COE of the sail does not need any lead over the CLR of the hull.

• The rig is a biplane junk rig with the masts set at the outboard edge of each hull in tabernacles.
• The hollow masts are Douglas fir built using the “birds mouth” 8 stave method, covered in glass and epoxy.
• The rig is a slightly modified Reddish rig with articulating battens.
• The battens are made of 1 1/2” alloy tubed with unidirectional carbon fibre covers.

Originally there was a mizzen sail mounted on the centre line, on the aft beam. This was designed as an ‘air rudder’ to help with tacking, but China Moon is exceptionally good at tacking on her own and the mizzen was removed.

The accommodation down below is as follows:

Port Hull

Forward in the port hull, we have a sealed, watertight compartment that serves as a collision bulkhead, keeps weight out of the bows, and provides space for empty jerricans. Some of these will hold extra fuel in case we intend to be away from civilisation for an extended period of time, while others will provide additional water for lengthy voyages.The heads compartment is located abaft of that. The heads themselves are at the forward end, with a wash basin on the port side, with storage underneath.

Heads

The heads’ own hatch makes it easier to use from the deck and eliminates the need to constantly walk through the galley. With floor-to-deckhead vegetable racks on one side and an oilskin locker on the other, the space between the heads and the galley is essentially a vestibule. At the forward end, there is an opening scuttle.

Galley

In contrast to Badger’s fantastic galley, the galley on China Moon is big. Additionally, we plan to use this hull at sea, especially in bad weather, so the counter area behind the Dickinson diesel cooker/heater will serve as a makeshift chart table. In addition, we’ll have a permanently mounted single-burner paraffin cooker, in use when in warmer climates. There will be plenty of room for lockers.

Saloon

The raised saloon along the entire width of the hull, will also heat this area more efficiently.

Six people may comfortably sit in the saloon, which is 6 feet 6 inches long, and eight people can squeeze in. 

There is plenty of book-shelves and storage in the galley.

Many, double glazed, windows along the outside of the hull (galley and saloon) offer uninterrupted view and provide plenty of natural light inside, when underway or at anchor, while cooking, reading or just relaxing. 

On the inboard side of the saloon there will be bookshelves in place of a window. Another window is looking into the cockpit, which is useful . 

Twenty-two fifteen- liter water containers will be stored beneath a table that runs along the centre.

Sleeping Cabin

Past the saloon, there is the after-sleeping cabin which has plenty of headroom as well as storage underneath and at entry. It  is placed in the most comfortable area of the boat. This bunk, which is four feet wide at the head, will serve as a berth for guests and is suitable for cold weather or at sea when we are keeping watch. There is plenty of storage underneath it and some shelves on entry.

Starboard Hull

The bow of the starboard hull also has an enclosed, waterproof chamber. There is a workshop with a suitable small workstation where we will store tools, paint, fenders, ropes etc.  The workshop is separated from the next cabin by a completely watertight bulkhead. This,  yet another watertight compartment, will keep the smell of paints, etc. away from the rest of the accommodation.

Master Cabin

The next cabin aft is a sleeping cabin, which we intend to use as much as possible, but certainly in harbour and in hot places. There is a good, 4ft 6ins wide double berth, with clothes lockers either side and another bookshelf, above which there are windows along the outboard cabin side.

The front of the cabin has an opening scuttle. There is a hanging locker and a little seat for comfortable dressing aft of the cabin. There will be additional lockers here because of the little wings. To prevent water from seeping into the sleeping cabin, a sill separates the floor from the chart room.

Chart Table

There will be plenty of room for charts beneath the full seize chart table and for books above it.

The ladder is across from the chart table. 

Additionally, the cabin’s exterior has windows – the same as in the port hull. 

As we will have to cross from one hull to another in the pouring rain and subsequently dispose of wet clothes, there is an oilskin locker here. 

In order to utilize the entire width of the hull and view out of the windows when seated, the area behind the chart table is raised (as in the port hull).

“Snug”

A portion of our library and a small solid fuel stove will be here. There will be a built-in table for computer so we can write in privacy and comfort. For chilly mornings or evenings,  that don’t require a Dickinson range to be lit up, we may use this ‘snug’ space as a place to warm up and relax.

We’ll need to see how it functions in actual use before we can be certain. Another advantage of this arrangement is that if we have a couple staying with us, we can turn this hull over to them in its entirety, which will give both plenty of room and privacy.

Engine Room

The engine room, which is large enough to provide adequate access to the engine and enough room to store a few bicycles, is located in the after end of this hull and is once more divided by a completely waterproof bulkhead. The reconditioned Yanmar 3GM  saildrive engine is ideal for a dory hull.

 “Won’t we go round in circles?” is the typical question we are asked. Our reading suggests that it won’t really be an issue unless we use marinas, which is not our plan.

Other JR Boats

Bob Bums of Roamer lied here for a whale during his circumnavigation. He visited us a short while ago and might be bringing Roamer here in November. Therefore, there is a chance of three junk-rigged boats being in the water at once at Port Owen Marina!