This from the Moth Home Builders facebook page:

3 june 2015

Time to add some spice to the home build conversation. I was once a keen home builder but sucummed to the purchase of a Mach2 three years ago. I have enjoyed my Mach2, but the experimental bug does not go away. I talke to a few people at regattas over the past year about this boat but I had nothing to say it had promise until this week.

This photos are almost a year old. Yes its a wing sail and yes it did make it to the water last year, and no it was not a success and yes it as a complete pain in the arse to transport, rig, launch and to sail with. Some good ideas, but mostly a bad idea for moth sailing. The back bit is in a big box and the front bit has been recycled into a new soft rig which seems much more practical and much more functional. The concept was for a deck sweeping unstayed rig with minimal windage and end plate effect. To do this the mast is 200mm forward than standard and the foot length is shorter to allow tacking behind the rig.

The hull is flat topped and the rig/sail come all the way to the deck, the CoE is consequently 500mm lower than a std moth. The hull is wider and shallower than normal to increase the end plate effect and reduce windage.

The hull and these features have been retained under the new rig which I tested for the first time last saturday. It has the same large dia main spar, and some of the same leading edge fairing, but these are no longer rigid and are suported only by special camber inducers so the fairing twists with the sail and battens.

The rig has minimal windage as there are no stays, spreaders or compression struts, and the boom, vang and cunningham are all inside the double skin lower part of the sail.

Its all home built with a lot of cost saving shortcuts hoping to prove the concept before spending up big.

But after only one sail which was abrieviated by breaking one of the main wing bars (made from broken sail board masts, I am sufficiently pleased to have confidence in spending more time and money on the project. It was less than 10kts and although I could not really get enough lift on the rudder, it did fly and it seemed to glide through the tacks withut slowing, But my body movements were limited somewhat by the wing tramps separating from the hull.

One brief sail only, but lots of promise. Wing tramps are fixed, rudder aoa fixed, wing tubes next, another sail in a few weeks. More photos of various bits if anyone is interested.

I have built 12 moths and owned 4 others. Thats as well as 26 other boats I have owned or built for my friends, myself or my family since 1962. That make this boat #42. For Douglas Adams fans that could mean that this is my ULTIMATE boat or the ANSWER to the design question for moth sailing. We willl see. Good name though.

 3 dec 2015

After 6 months off doing other stuff I am back onto this project again. The new wing tube sockets are in and the deck repaired. Bowsprit next, new telescopic wand needed. Some interesting things to do with the rig too. Might sail it before Christmas after the M2 gets loaded onto the truck for the Perth Nationals.

19 dec 2015

 Ready to sail today, wing angle incresed, the double deck is gone so I can see what all the controls are doing. I have changed the boom and vang arangement to make less impact on sail shape. Photos later today. Expect the unexpected. Its forecast to be a bit windy for a test sail, so hope it all hangs together.

 Rigged and ready to go, no windage from spreaders, compression struts, stays, boom, vang. Its all inside the sail.

 Sail needs some work, it was a bit of a rush this week after some delays getting the boxes loaded onto the truck for Perth. But I went sailing, completed the race, had a few issues which made tacking difficult, so quite a few swims. But nothing broke.

Some more details. The mast has two fixed levers, one at the top holds the sail out like a gaff, the one at teh bottom controls how much the mast and gaff rotate, so twist is controlled with mast rotation, like a CCat wing mast.

The bottom lever

 The camber inducers fit around the mast and extend forward to form a neat aerofoil shape. then the gaps between them and forward of the mast are covered with shells of K/C hybrid laminate

The shells

The whole rig is down to the deck, the mast band is at deck level, minimising lower tip losses, and reducing both capsize moment and total aero drag.

There are two booms inside the sail which is doubke skin below the bottom batten. Both have conventional type goosnecks just below the batten. They have pin joints at either end so can rotate. The idea is that they are half wishbone shape, hange vertically in neutral and rotate to leeward to match the sail camber on either tack. This first attempt had a bent boom for the longer upper one and worked Ok until one of the endplugs sliped in and jammed the pivot. The smaller lower boom just goes down to the back end of the mast strut, spreads the vang loads and gives teh mainsheet somewheer to attach. I used a straight tube this time but it will get a bent one next time.

 The whole rig is 200mm forward of standard, the centreboad is 300 forward of M2 position, so it really needs the bowsprit. When I sailed last winter without the bowsprit control seemed marginal, yesterday it was on rails. Foils used were M2 verticals, old large M2 rudder foil and a Makita main foil. My others are all in the box for Perth. The forward rig is to allow tacking behind the sail. Yesterday I had both booms a bit long and the vang line between them was below the sail, so I managed to catch it nearly every tack and fall over. this will be fixed next time, I just ran out of time after loosing a couple of days with teh truckies.

 The boat is amazingly quiet, even compared to other moths. I think it will foil tack easilly once i sort out the gap and my technoque, A couple of times It came about so fast I fell overboard as it accellerated, I just have to work out where to aim my bum or what to grab.

Hope you all enjoy the story. Not sure when the enxt sail will be, probably after Perth. Hope there is something here to inspire the mad home experimentors.