Haven't built anything for a while due to lack of space (too many models) but the urge to build something was too great. After looking at many options, I decided to go with something 'easy' to build. I found some full size plans for an Australian MkI Moth which I'm building to a MKII (double chine) style.

I'm building in foam and glass again to make things easier. It's 850mm long and 310 wide which is roughly 1/4 scale (original is 11 ft)

Started by converting all the lofting measurements on the redrawn 1953 plan to metric and dividing them by 4 to get the scale.
Next was creating the ply deck, then contact gluing onto it a piece of dense 50mm building polystyrene. This was then shaped with a surform file and the chines shaped afterwards using eyeometry. Then the 10mm deck foam was glued on so the deck sheer could be shaped.

Next the cockpit foam was routered out, and basswood sides and inner transom piece epoxied in. After that, the ply outer transom piece and hardwood nose block was epoxied on.

The centerboard case upper and lower ply braces were routered out (using the mill and a 1/2" slotting bit) large enough to accept the case sides, leaving enough room for the 6mm aluminium keel (can't use a centerboard for obvious reasons) which will have to have a bulb fitted.

A rebate in the bottom of the hull was routered out for the lower c/board brace. These braces are needed to form part of a box structure with the floor and cockpit sides which the c/board can lever on. Once everything is eventually glassed in, it will make it very strong unit, so the foam will just be the shape surrounding the box, and not having any strain put on it. The ply deck will take the strain of the stays/mast.

The cockpit floor was cut, and will be slotted the same as the braces, then the c/board case will be built.

The mast on this is 1.486m tall, - sail is -luff -11.295, foot 609mm, so quite large for a small boat. The full sized boat is a lot of fun to sail, so this model will be interesting to sail. Unfortunately, without the human input required, and being a performance boat, it may assume the attributes of a submarine in a stiff breeze, - time and testing will tell.

The basic mast was made from 12mm ally tube, boom from 10mm. Sail pattern was cut from art card to the plan. All laid out on the floor to get an idea of what it will look like.

PDF is the history of the Moth. There were a number of versions round the world as it went along,- scow, international moth (dinghy type) and todays high speed foiling moth.

Lots more to do yet

JB

2025 world champs, off the Whangaparaoa peninsula, just up from where I live.

https://australianclassicdinghynetwork.org/moth

https://www.moth.asn.au/

Cockpit floor is now epoxied in. The centerboard case is also epoxied into the lower reinforcing pad, ready for the unit to be epoxied into the bottom hull rebate. - (Pics added to show the centerboard case parts with the assembly method.) Once that's set, the upper centerboard case reinforcing pad, which is a firm push fit over the case will be epoxied in.

JB

Decent hot day today, so decided to f/glass the bottom of the hull. All the c/board case parts were epoxied in the night before and set well. The bottom of the c/board slot was filled with a tight fitting balsa square, and planed flush, to keep any epoxy from entering. When the glassing is finished, this will be easy to remove and sand back.

I put a coat of epoxy mixed with filler powder on before the 6oz cloth, and troweled it into the pores of the foam as a filler, then straight away laid the cloth on and rolled the normal epoxy through the cloth. This should help with fairing the hull later.

My Hitec winch arrived from a surviving model shop 80 miles south, and that will be eventually fitted in front of the c/board case, in the cutout. Lots more to do yet.

JB

Even hotter day today, (37C in the shed) so added some more f/glass. The bottom was trimmed and sanded back, then some glass tissue was laid over (the previous night) to help with fairing. When that was set, it was sanded back. The deck was then glassed with 200gsm cloth. After that set, it was sanded back, and a coat of thick resin and filler was squeegeed over the deck and bottom to get rid of a few imperfections.

That will all be sanded smooth, and if satisfactory, will be painted with a thick acrylic primer, with more sanding to go. getting closer to the fun part of making the fittings and installing the gear. Hull now weighs 1.4kg,- (was 1.3kg before deck glass) hoping it will end up around 1.5kg when painted

JB

More sanding and fairing done. Tried tinting one of the resin coats, and it turned out well,- another coat and I wouldn't have needed to paint it !. But- it showed up bits I wasn't happy with, so mixed up some more resin and fairing powder and gave it another coat. Sanded that back today, and gave the deck another white tinted resin coat.

Not getting too carried away at this stage,- just getting it to a stage worth undercoating, as I want to see if it sails before spending money on paint. I'll be tinting a colour for the bottom as well, as that's not looking too bad at the moment, fairing wise.

JB

More sanding and fairing on the hull lately, (not so much the last week, as it's been raining non stop the whole week, (big storm, see todays' rain radar pic,- NZ's under there somewhere 😐) - floods everywhere,- workshop downstairs has a tiny stream running through due to a retaining wall leak and water coming from underground,- happens whenever we get torrential persistent rain, eventually most drains out, then its mop time. Does no damage, just a nuisance. Just got my new bathroom roof on in time,- and no leaks,- good test though.

Re-resin coated the hull and tried using red tinted resin as a final coat. Looked good from a distance, super shiny, but was a bit opaque over the previous white and for some reason had a number of small 'fish eyes' from some wax bleeding through. I'd super degreased it, but it still happened. Sanded that back and tried again,-scrubbed it with degreaser and isopropyl alcohol,- same thing, same spots !*%^

Gave up, sanded it back and coated it with Zinsser stain blocker, which usually fixes most problems. Have to wait till the sun comes back to paint it with epoxy enamel.

Just finished building the rudder, stock and gudgeon and pintle setup. Rudder laminated with 3 pieces of basswood, then glassed using polyester aircraft cloth. Another resin coat after that. Stock was from basswood, coated with resin. Will be painted eventually.

Slowly progressing.

JB

Hull's back to red paint now after the Zinsser coat which fixed the fisheyes. Added some mahogany trim to the rudder stock, and have now cut out the self draining slots in the transom, (i think it's going to need them) The foam between the cockpit ply and transom will need filling and coating round the inside of the drains. Still have the deck to paint (over the white resin) and a veneer to go on the transom (varnished). After that,- fittings. Decided to leave the rudder unpainted, looks ok as is I think.

Rough weather slowing things down at the moment, heavy rain, landslides (unfortunately people missing,) slips everywhere, flooding etc . It's supposed to be summer !

JB

Deck has been painted now, and the walnut transom veneer epoxied on, stained and varnished. The winch has been fitted and the pocket it fits in has had all the foam surfaces (from cutting the pocket) epoxied to prevent any water getting in. Managed to get the ESC hidden in a side 'pocket, and the rudder servo mounted and working. A tunnel was bored through the foam between the rudder servo and the ESC, so as to keep the servo lead (fitted with a servo extender) out of sight and dry. Rudder servo will be waterproofed with Vaseline in the casing joints and round the output shaft, will also have a splash cover to keep anything major off it, and will be sealed into the cockpit side with some silicone. Self draining cockpit should let most of the water out.

The side pocket for the ESC, has a waterproof cover which will be screwed on once everything is finally installed and set up, after the cockpit is painted. The glass covering the bottom of the c/board slot, has been cut out, with the balsa plug (previously fitted before glassing) doing its' job stopping any resin intruding into the case.

The centerboard is something I've been working at,- thinking of ways to avoid having a large bulb, which would not suit a small c/board racing dinghy. Here's what I'm going to try as a way round it. If this works, it should end up with a slightly fat fin, rather than a big blob on the end. I'm only after good self righting from horizontal, but not a 'stick to the water upright' sort of weight, as the whole idea is for the boat to plane easily.

Re c/board. -- milled out the aluminium centerboard last night for the lead infill. I bolted the 2 50mmx3mm halves together with 3mm drilled and tapped machine screws, and they will be clamped over the block which has the same profile routered out of it, then filled with lead (hopefully it won't pour out everywhere!) The block itself will have another lot of lead poured in after that, to make the other side of the c/board, well that's the theory !  If it looks good, it will be glassed and painted.

At the same time as this, I've been knocking up a new improved beach trolley for my restored 11ft 70s vintage Cherokee racing dinghy, which is going on display with many other small yachts at our next Auckland Wooden Boat Festival in March, plus- putting a new roof on my bathroom,- so modeling progress is a bit slow at the moment. Hopefully pouring some lead today.

JB

Have poured the lead into the c/board mould and it came out well. I've filed the good side (wooden mould side) to a curved shape, and filed the top side flush with the aluminium center. I used a Surform file which I have found to be the best for lead, (a slightly used one is best as it won't grab). The filings and a few other bits will be used in the mould to make an identical side to be attached to the flat side, which will be filed to match the other side.

I've also rigged the mast, and made a pair of turnbuckles for the side stays. They were made from 5mm aluminium rod, drilled and tapped for 3 x 30mm machine screws. The screw heads were peened flat and a 2mm hole drilled through them. One end of each the aluminium rod was carved with the tip of the lathe tool by turning the chuck by hand and making a knurled effect for grip.

The top end of the rod was cross drilled 2mm, then cross cut at 90deg to the holes with a hacksaw. 2 small fishing swivels had one end loop peened flat on each to fit into the slots, then held in place with brass pins with soldered ends to keep them in place. Brass wire hooks were bent and soldered through the drilled screw heads for the chainplate ends.

Mast had a center drilled dowel inserted in the bottom for a locating pin, which was cyano'd in.
Stays were made from plastic coated stainless fishing trace, the trace was fed through a brass ferrule, through the attachments on the turnbuckles, back through the ferrules, adjusted and then crimped in place (leaving half the thread on the turnbuckles for final adjustment.)

Brass chainplates were made, and screwed through the deck f/glass into the ply sub deck below. Sail template needs some adjustment, then I'll be having a look at making the sail. The template is pretty close to scale, so sailing is going to be 'interesting" !

JB

Cut the sail last night using a Weller soldering gun, and managed to get the luff and foot taped ready to sew. Rather than make a mess with my sewing, I decided to take it to the experts a few houses down the road, where a couple of ladies do alterations in a well set up workshop. I'm getting them to sew the foot and luff, and sail batten pockets (which I made a wrinkly mess of on the first catamaran sail) . There is a special folded hemming? tape the lady showed me which looked ideal for those. Hopefully it will all come out nice and flat. UPDATED SAIL PICS

Also worked out the sheet hauler pulley system which is similar to the last day-sailer yacht I built. Comes off the winch one side lower than the other, so the initial pulley for the top of the drum, is slightly higher than the lower drum side pulley. The line goes over that and under a guide at the bottom of the c/board case, and back around the 2 rear pulleys in a continuous loop, as per normal. The dropper idea gets the lines down near the floor and less obvious. A bit harder to do than a yacht where the lines are all internal and out of sight.

The rear 2 pulleys are made from tuned down bungy tie down buttons used on utes or trailers, drilled out for a brass tube insert, and bolted to a ply plate with 3mm machine screws with nuts pressed and cyano'd into the bottom.

Sail will need fitting when it's done, and cockpit needs painting before everything is screwed on permanently. Still have to figure out how I'm going to fit the battery.

JB

Sail's now fitted to the mast, and battens made from resin coated 1.5mm ply. The mainsheet hauler is now sorted also. Managed to find a suitable small Li-ion 7.4v 1500mah 2s battery for the boat, from a large Chinese owned model shop - https://hobbystation.co.nz/ (one of very few shops left) as they must have the biggest range of batteries in NZ, (to fit the dozens of different RC vehicles, tanks, diggers etc they sell) I've managed to find all sorts of batteries there for various projects (eg modifying TXs to last for numerous outings and doing away with the AA batteries in my FSi6 and 10x TXs)- very good service and prices there as well.

Did an 88 mile round trip to buy the batteries, so as not to risk couriers losing them, but well worth it as it solves a bit of a problem with hiding the battery in the boat. On that, - I've now managed to fit the new battery by cutting another bay in the port side of the cockpit, and tunneling out the foam. Because the battery is 7.4 v, I've used a cheap voltage regulator (Ali Express) to set the output to 6v for the winch and RX. The VR sits in front of the battery in the cutout in a plastic bag to hopefully keep moisture out, and has a JST plug so the battery can be removed for charging.

I have another waterproof cover to make for the battery pocket like the RX on the other side. The rudder servo has been silicone sealed, screwed in place and sealed in its' pocket with white exterior sealer. The foam pockets have been painted with acrylic artists paint to keep any water from penetrating the foam and getting behind the cockpit ply lining. Shouldn't get too much water in, as the covers will have EVA foam seals.

The boom vang has a nylon spacer captured by a clamp above it, and can rotate with the boom. Luff is tensioned with clamps top and bottom, and the foot is tensioned with a boom clamp. I've made a couple of pulleys for the mainsheet as well. Splash cover for the winch is a cut down scoop from a set of 3 for $4. Still to be painted and fitted.

JB

99% done now, finished after a 12hr stint on Sunday afternoon. The RX and battery covers are done as well as the c/board spacers, c/board case top trim, winch splash cover, wiring secured and hidden as much as possible, and a few other minor bits and pieces. The 1% is for if it sails. I was hoping to try it today, but the weather changed from fine for a week to wind and rain, so will have to wait for the next fine day with light winds for testing. Keen to see if it's going to need a periscope😀

JB

Finally got to wet the moth after picking up my racing dinghy from the boat festival in the city. Wind had died down and was just right for a test. It went quite well but needs more adding to the c/board leading edge, as it wouldn't tack at first, with the c/board 20mm back from the front of the c/board case. Spaced fully forward it was slightly better, but I ended up reversing the c/board so the 20mm trailing edge was forward, and it was spot on.

Will be modding the c/board with 40mm on the leading edge (had the same problem with my catamaran) Unfortunately couldn't build the case any further forward because of the winch position. Boat's a bit nose heavy so will need some rear ballast. At present I'm making a tiller and a water diverting coaming for the deck. Only shipped a spoonful or 2 of water on the test, but the electrics stayed dry which was the main thing. A few mods and I'll give it another go.

JB

After the successful first outing, I've added a few more bits which I left off in case it turned out to be a total failure. I've added a tiller, cast some small 110g weights for the stern (to try and level the boat under sail), fitted foredeck coamings, and made a spring supported mainsheet block to prevent the block becoming tangled in the mainsheet hauler line (previously the block was on a cord.)

It's now on an eye in the floor, and the spring keeps it upright out of the way (same idea as a full sized stand up block) but still flexible. I've also painted and mounted the 2 lead weights on the rear cockpit sides. Ready for round 2.

JB

I've now made a new keel for the moth. It's 700g lighter but still has the same righting ability, as the weight is now on a slightly shorter skeg, but now as a bulb, rather than previously distributed over the length of the original c/board in a milled out center, (done for more scale aesthetics) The original only added weight, and a lot of it was wasted in the upper side and not doing much toward righting ability.

I made a new mould, and cast 2 weights using and equal number of lead ball sinkers. These were epoxied onto the skeg and bolted through with brass bolts for security. The skeg has a 20mm hardwood leading edge added, which is f/glassed on to correct the center of balance.

Managed to get a 2nd test sail after waiting for some bad weather to pass, and the boat now sails a lot better with the reduced keel weight and the 200g of weight in the rear of the cockpit
Sits with the hull level now, not as prone to 'duck shoveling'.

JB