We have 2 x Lake Lefroy Mini's,
The chassis spine on both is parallel to the ground.
The first one I built to the original plans - "Dangerous Goods" has 2 1/2" ground clearance under the chassis spine.
The other, built at the Esperance Skunkworks, [Chook's shed]- "Chook Chaser" has 3 3/4" ground clearance under the chassis spine.
stephen
More build pics....
2.0"sq tube
1.25"sq tube
1.0" set collars
.75" set collars
1.0"od x .75"id seamless tube
.75"od cold roll round bar
1.0"od cold roll round bar
.75"id hardened machine flat washers
.75" cold roll steering stem and .75"id x 1.0"od x 1.75" long head bushing. the bushing was .748"id so I had to machine it to .751" to fit the steering stem shaft
Bushing was also notched for 2.0"sq tube seam clearance
Drilled a .75" through hole 1.0" back from end and centered on one end of 2.0"sq tube
Installed and welded steering stem/head bushing inside 2.0"sq tube
Cut a .75" x .75" end plate for 2.0"sq tube. Tacked two shims to it in order to make it set back .125" inside tube
End plate ready to tack and weld in place. After the plate was tacked I used a chisel to break off the jig
Hardened washer welded to bottom of tube as a wear plate
End plate welded and stem installed
I cut a piece of 1.25"sq tube and center drilled a .75" through hole and welded the steering stem inside it. I left .125" protruding through the bottom for welding purposes. The stem is welded inside also.
Another hardened washer was welded to the top of the fork bar as a wear plate for the steering
It's turned at a 90 so you can see the configuration
That's it for now.
I gotta tell ya, that's the most work I've done in months
Will work on joining the spine to the rear axle next
That's better or it would have taken the rest of your pocket money to purchase Auto Bog Filler to fill the gap. Haha
Select to expand quoteGizmo said..
Now that a serious blokes shed in the background 
Ya It's pretty nice having a place to do some serious work. It's an old milking barn. 3500 sq ft. We do almond harvesting and the barn was converted so we can do the winter service on the equipment. I only wish the floor was concrete, if you drop something small you better have another one cuz you'll never find it again. I'll post a pic from the end door because that's just a tiny part of it.
I cut the spine tube at 22.5 degrees and welded the the parts together with a stick arc welder using .125" 6013 rod at 90 amps. I will be adding a thrust washer between the gooseneck and the fork cross bar.
I'm sure the bride is going to love this picture! When the cats away the mice will play....or is that, the rat will play?
I am going to re-do the front end. I don't like the looks of it. I made a die for my wrought iron parts maker so I can bend 1.250" sq tubing. Or I will just remake the forks to match the drawing I posted. As it turns out the chassis as it sits weighs 58.5 pounds or 26.5 kg.
Any questions or advice at this point?
Today I cut a piece of 5/16" rope at 219.375" = 5.572m to make sure I am within the 5.6m rope rule.
I used bigger rope and just a little short to make sure I have some wiggle room and will always be within the limits of the rule. I'm sure I could squeeze another couple of inches of wheelbase out of it using the proper length/diameter rope but I will never have to worry about getting DQ'd for that.
The way I made a loop of rope the exact size I wanted is I cut the rope a .250" long and melted the ends together. Came out perfectly to the cut dimension above.
I also cut the mast step out of a piece of 2.375" gal. conduit and came up with some peddles.
Using that smaller loop your yacht should be a "Shoe-In" size wise.
Shoe-In
How's that for a name for your yacht
After making the 5.6m rope and adjusting my wheelbase to it, the wheelbase is now 69.0"=1752.6mm instead of 66.5"=1689.1mm. Should make for a little more stable yacht, I think?
The mast step can now go as far forward as 50.0"=1270mm from the rear axle center line.
I also added a .750"id Oilite bearing between the frame and the steering tree.
Select to expand quoteKAONAONA said..
Today I cut a piece of 5/16" rope at 219.375" = 5.572m to make sure I am within the 5.6m rope rule.
I used bigger rope and just a little short to make sure I have some wiggle room and will always be within the limits of the rule. I'm sure I could squeeze another couple of inches of wheelbase out of it using the proper length/diameter rope but I will never have to worry about getting DQ'd for that.
The way I made a loop of rope the exact size I wanted is I cut the rope a .250" long and melted the ends together. Came out perfectly to the cut dimension above.
I also cut the mast step out of a piece of 2.375" gal. conduit and came up with some peddles.
thats actually a brilliant idea
that tube you used for the mast step is what you should use for the main spine of the chassis. square isnt very good at all
DObbin?
Here is the semi completed pivoting mast step tube.
Stick welded with 3/32" 6011 rod at 90 amps DC.
So far so fun. So much fun I'm going to start another one as soon as this one is sailed. I already have a lot of the parts and material. This is a lot of fun and has re-established an old friendship with an ex coworker. He let me use his mill and lathe and was stoked to see what I was working on!
Select to expand quoteGizmo said...
So how it the mast tube being supported to hold it up?
Two of these 5.0" tie rods.
They are 3/8-24 and have both left and right hand threads.
Like this.
I think one support would be fine but I'm using two.
I will give it 10 minutes before it breaks.....
Think of this..... if the mast is 4m long and you have 50+kg of force to flex the mast to how you want / need it that means a mounting 200mm from the mast base will have to put up with 1000+kg force (20:1 ratio) than add some twisting force because of a jibe....... 10 minutes tops!!!!
Gizmo, I think it will only take 8 minutes!!!
Koana, I have a similar setup on my mini which hasn't broken down yet, it works fine but uses a 1/2" threaded bolt spaced further away from the mast pivot, in fact ahead of the steering shaft - shown in my photos collection. I would go a little bigger again as I think I'm right on the limit and am surprised the mast hasn't come down. The mast in fact did come down first trial when the pivot bolt tore through the mast tube walls, so beef that area up. My side cheeks are 1/2" x 1 1/2". T'was an embarrassing moment in front of onlookers at the time.
I see you have used square tube for the spine. I suspect it will be too rigid. Round tube allows flexing along the spine storing the energy. As the flexing force reduces( either a gust of wind, direction change or even bumps in the terrain) the energy is transfered to the wheels as more power/speed.
Where is it that you think it's going to fail?
Where the rod is attached to mast step and steering head. If as it seems in your picture the rod has eyes at each end and if you attach at pivots you will have even less lateral support for the mast step. I hope your system works as you seem to have a light weight(minimal strength) design in mind. Again a flexible spine would help.
i will follow through with this build and keep all the material suggestions in mind for the next one. Besides, me being a big boy I need to go as light as possible next time, for sure! I weighed it today with me on it and it came out to 305#. Too heavy, no doubt.
That kind of sucks because it only weighs 49# by itself! I make turds bigger than that!!
I too am a big boy. Thats why I was the test pilot for the original LLM and our Promo's. It was on my yacht that the mast step tore out of, nearly crushing my ankle in the process. That lead to the reinforcing strap under thr mast step
my suggestion is to just follow the original proven plans and not to reinvent the wheel for your first yacht. and go out and enjoy sailing it not repairing it.
Not sure what it is you think is going to fail.
The pivot brackets?
Or the mast step pivot?
Or the tie rod strut supports?
The tie rods in the image above are what is used to hold the rear axle in and under a quarter midget race car and only seem to have ever failed in a crash, if even then.
My pivot brackets are 1/2" thick but I think yours will be ok. My pivot pin is 1/2" high tensile and the base of your mast is almost exactly how I re-did mine successfully as previously I only drilled a 1/2" hole through the base of the mast tube - that is where the pin ripped out of the thin walled mast tube.
I would worry about up-sizing the adjusting the tie rod and its attachment to the mast post and chassis.
Whatever you do, if it fails then it takes only minutes to re-weld the failed spots. Enjoy the sailing...w
There will be two rods side by side equaling 3/4" between them.
Also i'm pretty sure my mast pivot pin will not tear out of the 7/8"od 1/4" wall tube welded to the bottom of a 3/16" plate that is welded to the bottom of the mast tube. Plenty of surface weld and more than enough mass.
By the way I like your videos on you tube. You and Alan Watson get some pretty good footage. I love that winged unit you run. I thought you had a mini with a wing on it! Or was that Vic? That one is pretty sweet too.
My second build is getting under way and I'm planning in competing for the Americas Cup of land sailing next time around. I am also going to attend and race at as many events as I can in order to utilize all that I learn from the "old salts". I want to do well so their efforts to help me are not in vane. I appreciate all the input form other pilot/builders.
My plan is to have a two or three pilot "racing team" I will also try to help as many other pilots/builders/competitors to succeed, as I have been helped by others to succeed.
Thanks to all for your support!
It' cool that a simple design like the mini has drawn in people like yourself that have some building skills. I know once you experience sailing on a drylake bed that hook you in for good. Basically these dirt boats are trying to twist them selves apart. The first one I made was out of wood and the floor departed from the side at the axle junction. A few chunks of 3/4'' plywood ,some aluminum straps and 5 minute epoxy had me back on the race course in a few hours. The other mini is all steel frame work. The axle is bolted on to a few 1x 1/8'' straps that run between 2 bulkheads. The strap tore the thin wall metal tubing that the bulkheads are made out of. Wider straps to distribute the (weld) load fixed the problem.
