I have built two Lake Lefroy Mini land yachts for use on the Australian NSW north coast beaches.
This means that compared to WA salt lakes I expect softer ground, lighter wind, less chance of a favourable wind direction and sloping beaches.
Since I’ll only get to use them on holidays and won’t race them, I haven’t spent much time or money on the sails or body.
I used wheelbarrows for the body and 7m windsurfer sails which are larger than the design recommends.
The result is fast and fantastic.
Maiden voyage:
Build and performance trials:
.be
Thank you Paul Day and all those who worked on the mini-explorer design of a Lefroy mini.
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/Build-a-Landyacht-Lake-Lefroy-Mini-Yacht/Thank you to those people who published their experience with building mini-explorers.
Here are some construction notes about my build.
Mast step:
To accommodate the larger sail I made the mast rake 5 degrees not 10.
The steering pedals did not allow me to move the mast step further forward without making things complicated. I don’t think that is necessary anyway as the craft handles very well.
The mast step to spine junction requires a pretty cut to the mast step. At MetalGeek.com
metalgeek.com/static/cope.pcgi there is a free online program ( a tube coping calculator) to generate the pattern. You input the pipe diameter, wall thickness and join angle to get a pattern to print. Cut this out, tape it around the pipe and mark the edge. Nice.
I slipped a little wooden block into the mast step so that the fibreglass mast would not grind on the spine and welds in there.
One yacht’s spine was 4mm walled pipe, so I could not flare the mast step top just by hammering it over my tow bar. I bought gouging rods (copper sheathed carbon) to make a carbon arc torch, but did not have enough amps to get a constant spark going. So I just played the carbon rod over a 30x30mm square area inside of the pipe. Then I could get in three good hammer blows to the inside. If I had thought to use the rod on the outside I might have had to spend less time filing off the roughness this made. This was quick enough, the result just fine.
To protect the mast further I cut 4 vertical slits 50mm down the mast step.
I could not imagine the fibreglass mast being supported by a 200mm mast step so I made it 400mm.
To strengthen the lower section of the tapered fibreglass windsurfer mast I inserted another mast then withdrew it and cut it to 1500mm. Then I inserted a tapered 500mm wooden plug. I did not glue these as I think this way they distribute the load more evenly. I wish I had put a little glue in so that the pieces could not slip out when the mast is on the car roof. After 5 hours use the mast has not broken or cracked. I will fit a loose outer sleeve of PVC or whatever into the mast step. The strengthening has not prevented the mast from bending as it should.
Sails:
One sail is a Gaastra 7M with camber inducing battens made in 1987, still good as new. The area below the boom has been cut off and the clew for the downhaul re-attached. There is now a pocket for a boom in case I decide the wishbone boom is no good. I might have done better to extend the mast, not cut the sail, which my wife claims was hard work.
The other sail is 7M with no battens. The mast pocket has been cut away a bit to accommodate the mast step.
The camber induced sail seems to provide a lot more power, especially at low speed in low winds.
Mast length 5M.This page shows how to recut a sail to make a high aspect ratio 5m sail.
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Sail-making/How-I-recut-sailboard-sails-to-suit-landyachts/Rigging:
The windsurfer boom pretty much limits the main sheet attachment to the outer end.
This only needs 2:1 purchase.
I ran the main sheet from the rear post to a pulley on the axle close inside the starboard rear wheel, then to the mast step pulley and then aft. This used a mounting point welded on the axle 25 x 50mm x 6mm extending forward like the body mounting lugs. The main sheet did tend to tangle around the rear post but the rig was otherwise good enough. I’ll try some other options. It might be possible to use a bridle to sling the main sheet pulley from both boom arms half way out. Then perhaps I’d need a 3:1 purchase to a mounting point between my knees.
A cam cleat for the main sheet mounted inside the bucket would be nice for when I get bogged and need to turn both wheels by hand.
My main sheet post is not demountable, 25mm for its full length.
The handbrake is only useful on tarmac with a wooden tip attached. On the beach it is useless, unnecessary and something else for the mainsheet to tangle around.
Paint:
Cold gal spray can, filled all spaces with expanding foam, gloss black enamel top coat, seems fine.
Body:
The seat is a $40 Saxon 60litre bucket wheelbarrow from Bunnings. It is mounted with 4 bolts, large washers, through the ply to mounting lugs. It is not secured to the rear post. It is strong enough, very comfortable, secure and required no modification. The wheels were a welcome bonus (16mm shaft).
I regret not installing a front mudguard, ptuiwee.
The floor is 6mm marine ply 1210mm x 440mm with the front end cut to a circle, keyhole for mast step and brace. Maybe 6mm is a bit too thin but 10mm would be a bit too heavy. The ply reaches across the top of the rear axle to support the bucket. It’s flexible enough so that the out-of-plane mounting points don’t matter. I added two mounting brackets for the body at 400mm and 1070 from rear.
Cut 2 of 300mm x 25mm X 3mm flat bar with holes for the top, 280mm x 25mm x for underneath. Use an off cut of the spine clamped alongside the spine to help you clamp these nice and squarely aligned above and below. Weld them on. Hammer the underneath bar to bend it up to touch the top bar inboard of the holes. Clamp and weld. Lovely. Spine:
I ended up with one spine at 60mm x 4mm and one at 60mm x 2mm. There was no advantage in having 4mm, about 4kg extra weight.
I added a reinforcing 25mm x 3mm wrap-around strap to the 2mm spine’s mast step – described somewhere on this site.
To mark the cut for the 60 degree spine end I made a jig from a 1500 x 100x50mm timber and sheet of ply.
Cut the 100 x 50mm at 60 degrees. Cut a 300x70mm slot in the ply and screw it to the end of the 100 x 50mm timber. Clamp the timber accurately lined up with the pipe. Lay a steel rule flat on the ply and slide it around the pipe as you mark it like this. 
Assembly:
I spent a lot of time making sure things were all aligned all square before welding.
It would have been good to have made a squared X/Y/Z axis from 3 x 600mm x 20mm tube and welded that to the middle of the spine as a reference point and sight line.
Welding:
I did 3 nights of a welding class 30 years ago and 30 minutes practice since, some googling on the day.
I tested my suspect work with a hammer grinder till I could see the connection between horrible and weak.
The first yacht took ages while I welded, ground off and welded again until I worked out how to use the broken knob on the front of the welder box.
No-one else noticed how ugly my welding was and none of it failed.
2.5mm Satincraft rods worked well.
Wheels and tyres:
270mm x 80mm diameter tyres are too small, harder to start and quicker to stop where the sand is soft.
I bought small diameter tyres. Luckily the wheel barrows came with bigger 350 x 70mm tyres. Of course they won’t last. I’ll buy the recommended plastic Fallshaw wheels and tyres later.
I left my axles longer than necessary, to be cut after I get some better wheels, drilled pin holes positioned for each available wheel.
16mm diameter axles seemed strong enough.
The steel shop had 16mm “bright steel” rod that was a tighter fit than the available galvanised rod.
I could not re-inflate one tubeless tyre after I lost the seal trying to pump it up at the beach.
Materials:
The square tube I found at the hardware store was 1.6mm walled. The design calls for a 2mm wall and that is necessary.
I found all the steel at Edcon steel and the nuts and bolts at their Bomond Trading shop. They will sell you the length you need and cut it for you at a price per cut, on a Saturday. I went overboard with this but appreciated the square ends.
I notice that windsurfers are hard to find second hand on-line, some are at the re-cycling area at the tip.
Edcon steel stock aluminium tube although they don’t list it on their website.
Weight:
Frame , ply floor and bucket: 11kg (using 2mm walled spine)
Wheels, axles, steering column: 11kg (350mm tyres)
Add mast, rigging and sails.
Me: weight: 75kg (Height: 1710mm)
Cost: Steel, $40 cutting fee, gal paint, welding rods, carbon rods, wheels, bolts, drill bits, grinder discs, hacksaw blades, axle pins: $400 each (wasted about $75)
Add more paint, better wheels, sails, running rigging, masts, rigging, tools.
Performance:
On fairly flat, firm tidal beach sand at 10 knots wind speed the yacht can tack to windward travelling up-slope (slowly) and fly on other points. Above that wind speed is all fun. Wind speed in the video is 10knots in some, 15 in others. I expect that 8 knots will do on flat grass.
The windsurfer boom cracked my helmet, glad I had it and the safety glasses.
There is no need for a wider or longer wheel base even if you won’t race.
The metal specifications in the design are spot on.
The foot "roll steering" is necessary and perfect.
BillNSW
