The evolution of my Lake Lefroy Minis.

It all started out with a google search for a land yacht in November 2010.
I wanted to take part in the "Recycle Regatta" here at Pink Lake in Esperance West Australia, where using recycled gear was the object of the competition. I didn't even know what a land yacht was till then.
"seabreeze" with "landyacht's LLM" plans popped up and I've been haunting everyone ever since.

"sn" on this forum contacted me. He said he would chase up some sails and masts and the rest is history. Stephen has been invaluable with his ability to scrounge gear for me.

From the timber body on my original 5 mini yachts for the Regatta, I soon worked out that I needed a better setup.
(I still have not found a source of hardwood welding rods.)



"Landyacht", was kind enough to sort out a fibreglass seat and this has worked perfectly for me.
I really like the idea of a standard fibreglass seat and I can then concentrate on the configuration of the chassis around me.

Slowly but surely the setups have been altered and not always for the better. My last chassis I have just finished tidying up has been through 3 major alterations and I have finally painted it green so as not to dice it again. (I hope.)



Not a lot needs to change from Paul's original LLM plans as they sail particularly well with a 4.5m2 sail.
BUT, I'm a large fella at 108kg and really pushed the boundary with up to 6.9m2 sails on a mini.
So the development of the mast step has been necessary to keep them pointed in the right direction with a sail size that's well outside their original design parameters.





The rear axle was widened on "Saltern" and the steering trail reduced to 10mm from the 40mm I had been using on or softer Pink Lake. Mast was standard as in the plans. This was a positive move.
The Velcro straps are to retain learners legs,to restrain them from putting them out when the yachts capsize. This yacht always goes with me to the lake for newcomers to have a go on.



The next chassis was extended 75mm on "Saline by" and dropped closer to the smooth salt surface with only 45mm of clearance underneath, this helped a lot with the bigger sails. This is the one of the only chassis I'm yet to alter as it takes the pulse jet attachment. I'm not really sure what I was thinking when I dreamt that up.







My next test chassis, I altered the seat shifting it forward 75mm to get more weight onto the front wheel which also worked much better. I had changed the trail on the front wheel to 50 mm but it was not working any different to the 40mm standard one I had. These can be changed by undoing a set screw a bolt and removing a minsup clip. So a couple of minutes and you're back sailing/testing. I cut this chassis 3 times just behind the mast adding 50mm more length to it each time and the mast is now 150mm further forward than a standard LLM but the mast is at 3 degrees of rake. I then removed 75mm from in front of the mast to comply with the 5.6mtr rule.



"Fowl play" was an experiment with rear wheel caster and has 3 sets of axles from 8 degrees, 3 degrees and also 1 degree. 2 front ends with 10mm of trail and also one at 40mm. A 10mm longer chassis and still has 35mm to spare with the 5.6 mini wheelbase ruling. Its mast step was the main difference as the mast was adjustable with 150mm fore/aft position and also from 2-10 degrees of rake. I tried to get a mast rake on the go sorted out and after 3 forward chassis rebuilds, I gave it away and it's as you see it here. This has been the biggest improvements I've made to date. The adjustable rake is fantastic as it is easily adjusted, in the change or surface conditions from Rock hard salt to softer powdery gypsum. The steering is now very point and shoot at 10mm of trail on hard ground and great on softer with 40mm, even when fully powered up with large sails.



The latest mini is "Chicken salt" and "Hiko" sowed the seed to get the mast step right up the front of the chassis and still be adjustable from 0-10 degrees of rake. The steering has only 10mm of trail and the seat is mounted in the 75mm forward position. Ground clearance is still 45mm. This will be my mount for Lake Lefroy this September. The forward mast step is as far as practicable to the front of the yacht and should prove whether it needs to go to back slightly. Time will tell. The axles have 1 degree of camber.





"Poultry in motion" is a chassis that has done many hours on Pink Lake and has been cut up way too many times. I had been experimented with how much 8mm, 10mm and 12mm rod is used to brace the rear axle. 12mm is the way to go as you can see with a Go Pro camera, how the others flexed too much. It's amazing how much that 60mm by 2.5mm wall pipe twists at this junction. I just ruled a texta line along the length of it, on the bottom of the pipe and filmed the differences from the camera mounted from behind.
Having the rear of the 60mm pipe left open and then closed was tested. A "D shaped" cap, welded in to close it off makes a huge difference to the unwanted rear axle flex. It's better to use the spine twist to store the energy created by a gust than the junction of 2 components. It also keeps the moisture out.

Seating positions have been shifted up to 150mm forward and now the mast is 150mm forward from a standard LLM and welded on at 3 degrees of rake.
The welding on this chassis is not very flash as it was a, weld it up and lets go bust it approach when making the changes.



I'm still learning a lot about sails and how the different types perform and what changes to mast stiffness seem to work. This is what makes it such an addictive past time I reckon.

A huge thank you to all the input we get to this forum. It's a very poor day if I don't learn something new.

Gee lots of enquiry about the yachts today!!!!

So to answer the questions.

The overall width to the outside of the rear tyres at their widest point on Fowl play and also Chicken salt, is 1585mm.
The length, axle centre to axle centre is 1705mm. With these measurements, it has 35mm to spare in the 5.6mm rule. (Using 10mm hard nylon rope.)



It's hard to explain the seat position. I'm 1830mm, tall or 6'.
The seat is mounted with it's lowest point (where my bum sits) it's 120mm ahead of the rear axle centre. You can see the 10mm water drain hole in the fibreglass. The seat mounting bolts which are also the seat belt anchor points, are 75mm ahead of this centre axle point.



The steering pedals are 1200mm from the rear axle centre.



The mast step which is 90 degrees to the main spine of the chassis at the back of it, is positioned 1345mm from the rear axle centre. The camera has distorted the actual measurements when taking the close up shots.



The chassis on both yachts are identical it's only the mast steps that are in different positions.
Fowl play that has the fore/aft adjustable mast step is 1000mm from axle centre and "Poultry in motion" is at 1083mm and fixed at 3 degrees.
All my chassis are 60.3mm by a 2.5mm wall galvanized pipe, made from bent street signs that I collect from my local shire at no cost.
Hope this clears up the questions.

Chook

My Dad would have loved your pulse jet Chook.

Great thread chook very informative You sure have a great line up of minis there
Since I have moved the mast forward on my mini I have gone to centre sheeting and all the sheet loads are on the
chassis instead of the back of the seat Usual setup for class 5 Just a thought for you to try
I like it but the boom needs to be stiffer than required for the other setup
regards Hiko

I agree Wayne. I harped on to our local bloke but he knew better.
I had the photos of both seats of your yacht and George's, taken when we were in Norseman in 2011, with the sun behind them to see through them and how they were reinforced but it all fell on deaf ears.



Much wiser now and I'll get it sorted out myself with Greg's help here.

The centre sheeting idea Hiko is sound, as it does load up the chassis in the correct place.

The main reason I prefer rear sheeting is I can set a good downhaul with huge tension and then add to it with clew sheeting pressure .

Much kinder to the hairs on my legs as well.

Thanks guys.

Nice read! It sounds like moving the mast forward is a good thing. Have you raked the rig back after the mast is moved forward or leave the rake alone? Does the rake change from 6.9 to 4.5 sm sails?
Thanks
John

John I'm guessing YES, for the mast rake. The yacht damage meant I couldn't do any testing.

Hiko, we had a big discussion about camber while the racing was suspended due to gale force winds at Lake Lefroy.

My yachts are at 1 degree with me aboard. My actual GPS testing has proved that this setup is faster but still with good handling.

The other guys seem to go for the camber angle to intersect the centre of effort of the sail. This seems to be between 7 to 9 degrees on all the yachts I got to measure.

I have tested these angles using scales to tow the yacht across a very flat surface and the 1 degree always had less friction. BUT!!!
The guys said to do the test again pulling the yacht from the C/E height on the sail and see how it adds up then.
I understand this reasoning that the centre line of the wheels, will be in line with the C/E when loaded up and the load will then be transferred vertically down through the wheels with less side load on the bearings.

Lots to work out here. Please chip in if anyone can explain it better.

I'd really love to know.

Excellent review and very helpful
Coremat always has been and always will be crap. It is blotting paper that adds absolutely no strength. It does add panel stiffness, but any of the guys I mix with who race fibreglass products of all sorts will never pay for product where it is used. Weight for no gain.

Kiwi
Bikes and wheelbarrows have castor so when laying them over isn't that what makes them turn ?
Rear axles on landyachts don't normally have castor Just thinking aloud

Actually this is quite interesting I don't have a bike handy to lock the front wheel and lean it to see the result
I imagine it would still track straight?
Wheelbarrows I believe though do have castor by virtue of the handles (the rear steering pivot point) being higher than the front axle (the front steering pivot point) Wheelbarrows then would also have trail
If the front wheel axle was the same height as the handles then no it wouldn't have castor in that case but I have never seen a wheelbarrow with a front wheel that large and if it were leaned it would track straight? Or have trail either
So it seems to me that just leaning a wheel has no turning effect at all
We see this on class5s pull the yacht along on all three wheels and the yacht rolls free lift the front wheel and the drag is immediately felt one wheel fighting the other as castor is introduced to the opposite leaned wheels
Me thinking aloud again

**We see this on class5s pull the yacht along on all three wheels and the yacht rolls free lift the front wheel and the drag is immediately felt one wheel fighting the other as castor is introduced to the opposite leaned wheels**

Interesting thoughts there. The term "Castor" isn't the one to consider on the rear wheels, it is Camber and Toe-in.

Assuming the rear wheel axles are angled to produce wheel "Camber" and aligned correctly there will be minimum rolling friction. When you then lift the front wheel off the ground it will cause the axles to rotate and introduce "toe-out" to those rear wheels. The rolling friction will increase the same as if your car had front wheel toe-out....a good way to wear the tyres out, burn fuel and head for the bush. If the rear yacht wheels had zero camber due to a solid straight axle it wouldn't have a problem. I tend to think that a flexible rear axle might produce awful tracking problems as they flex. What do the experts have to say??

Well I said I wouldn't modify "Poultry in motion" but another chapter has emerged so I just nicked the seat off it, for #24.

Running with uncut windsurfer sails has moved me towards "Greg's" newer design of mast step. The chassis is the same configuration as "Chicken Salt", just reinforced more around the T/spine to axle intersection as they were bending slightly. Compressing the 35mm x 35mm x 2 RHS each side of the top weld.
The underneath had already been beefed up with a triangle of 25mm x 25mm x 2 as a gusset each side, extending out past the upward bend underneath on each side.
No more cracked seats either with the support to the rear.
The cold galvanized paint is still wet here.

The mast step is replaceable with whatever angle "stalk" (that the mast slips over) as required.
Both the base mountings are welded to the chassis at 3 degrees of rake.
The 2 "Stalks" I have made are one at 2 degrees and one at 5 degrees.
By reversing them you have a combination of positive and negative rake angles.






The bases were machined up in my lathe bolted together as pairs at each angle.

The sides of these bottom 75mm x75mm x 16mm thick plates drilled and tapped to take 35mm long 12mmx1.5mm pitch cap screws, are supported by 30mm x 6mm gussets along the chassis with 2 small 6mm thick triangles at the front.
The bottom of the mast stalk is only 12mm thick flatbar. The stalk was tacked preheated then welded both sides (after the hole was chamfered for the weld.) The bottom was then touched up with the grinder to be perfectly flat again as the weld had distorted the plate.

.
Here the yacht is fitted with a 5 degree stalk. made from 51mm OD x 31.6mm ID, 4140 grade hollow bar, that's 350mm long, (giving me a negative 2 degree mast rake in it's forward position for a 8.5m2 sail.)
The surfaces where the mast slides over and is supported are 30mm in width. The stalk is reduced 1mm in diameter between them. So the mast rotated easily.
The Boom doesn't move on the mast at all, as it rotates as a unit.

The 4 gussets around the stalk was built up with the welder.




The mast stalk is at negative 2 degrees here.


Here is the mast setup with the 6 to 1 downhaul. The boom yoke is trapped on top of the strap to pull the bottom of the sail tight along the boom.


I use a shackle rather than rethread the downhaul rope each time. I never remember my glasses to see. The boom is attached to this shackle and then the downhaul triple pulley to the boom inturn.



The outhaul on the sail is pulled as tight as I can manage it. No need for adjustment, as to have the sail fuller this is done with downhaul only. This is the only mod to the sail as the outhaul eyelets were very high up.

Here the mast is fed into the mast pocket just to seat the tip of the sail onto the mast tip. There is an aluminium extension on the top of the mast to lift the sail.

Now only downhaul added to clip on the cams. Note there is no sheet tension, (or very little) required as this only tightens the mast pocket and makes it harder to get the camms on.




Camms on and a bit of sheet tension now to stop camms popping off. (If they pop off the mast the downhaul is to loose, or too tight they are impossible to get on.)


Now stand it up and pull the downhaul with all my might!!!!!!!!
Here it is fitted with our "Pink Lake" all terrain wheels.
Note how it's ready to sail without a single wrinkle and look at the sheet rope!!!!!

If you look closely at the rear of the seat you will see that the pulley blocks have been lowered, as I had them set up to close together for the additional becket block.

This is what I raced at Lake Wallungup in the States with a smaller sail. It's done over 500kms now, with only the rear axle and pulley block mount mods done to it.
Hope I have explained it well enough?

You have taken this to a whole new level Chook Using the unaltered Windsurf sails makes sense to me it just took someone like you to figure out how it could be done. The class 5 type wheels though takes the yacht out of the mini class I would think ? How do you race with those ?
Anyway well done

Wow what a venue ! A bit different to our 'ribbon of sand 'sailing. That yacht of yours is going really well
Thanks for sharing