I would like to post a drawing of my mast which I designed using the drawings by Paul. This design would simply fit right into my base piece and allow my to retain everything else on my land yacht.
(If there are any issues with reading the drawing, let me know)
A few questions I have:
1. Is the diameter of the entire mast going to be too small for my land yacht?
2. Is the wall thickness to narrow for this size mast?
3. Is the clearence between tube walls at .0045" [.114mm] going to be a problem? I have some smaller diameter tubing just like this and it slides in very nice. But if there are any imperfections it is very difficult to slide in and out. Not sure what the stresses of a sail will do to this tubing.
In the drawing I show 6061 T6 aluminum. I can purchase all the pieces for $170 US. I can also purchase the same diameter tubings in a 6063 T832 aluminum for only $90.00 US. But I am not exactly sure how much softer the 6063 is, and what the difference is in the temper.
And my last option and possibly best option would be to simply re-design my bottom mast section to allow for a larger diameter tubing. I was also considering using the smallest diameter tubing in a thicker wall all the way through the mast.
Here is a link to some photos of my land yacht: webshots.com/weekly
Total weight: 140lbs / 64kgs
Mast height from frame: 18ft / 5486mm
7.0m sail
Thank you in advance for any comments and suggestions on helping me re-design my mast. I am very excited to get back out and start sailing again.
Terry
In Australia the T6 series is almost always thicker walled (3mm+) the tube we use is the T8 range and are usually1.5-1.6 mm wall.. my inclination would be to run the narrowest tube the full length, then the next size.......etc ie have a good thick base with all the sections starting from there.
the diagram didnt translate to a BLack background , so Im not sure of your dimensions..
beautiful looking piece of desert youve got there
Jus read the other thread. If you start with a 44mm tube at the base I think it will snap/bend. I tried this on the mast of a yacht called wee,wee,wee and it snapped regularly. you will need to go up a size to the 48mm OD for your outside diameter.
this will mean making a bigger steel support tube. I would make one that can also take a sailboard mast INSIDE the tube. I think that the way you set up the sailboard rig is probably the cause of the snapping.. all the stress of the rig has been focused to the base of the boom. have a good look at how blokarts avoid this stress point by taking the sail past the A frames .
Thanks for the info. I will design a new steel base support that I can slip at least a 48mm or 50mm tube into to start with. This will give me at least 400mm of overlap between my 3 pieces of aluminum and the steel base tube.
As far as the wall thickness, it sounds like the .58" [1.473mm] is about what you guys are using. This is the only wall thickness I can find that will slip into eachother very nicely. I can get a .065" [1.65mm] wall, but there will be a much larger 1.5mm gap between the tubes. I feel that is a bit too much slop and some sort of a spacer would be necessary.
When you mention T8 series aluminum, would the T832 fall under this category. (Sorry if this is very obvious, just want to make sure).
I'll post a white background picture (autocad defaults to black) for my dimensions.
El Mirage is a great place. It is about 8km long and 2km wide at its widest point of smooth lakebed, and it's always windy! Not sure why it has taken me so many years of going there to finaly start sailing there!
Thanks again for your help.
Terry
These are the sizes available from the place I would purchase from:
So I was planning on using the 2.00" [50.8mm] and working my way down from their as shown in the drawing below:
My new steel base piece will have an I.D. of 2.00" [50.8mm] so I can fit my largest aluminum tube inside. I can purchase all this for about $110.00 US which seems like a pretty good price.
This will be my first experience with this type of mast, and I am hoping it will be strong enough to handle my 7m sail with a heavier land yacht like mine.
Terry
Thats a better range than we have. we have 3 OD sizes that fit and thatsabout it.
You should be able to make a rippa mast from that range
your prices are kinda sweet too
Good to hear that these tubes should work out. Would you start with the 2.00" [50.8mm] O.D. tube as your largest outside tube, or go the largest size available at 2.125" [54mm] to start with? I'll be using the full length of the tubes (except for the bottom two inner tubes) at 6 feet each [1828mm].
I really appreciate your help. I feel much better about what I'll be purchasing.
Thanks.
this decimal point with inches is a bit hard for a metric boy.
The trick is to mke the mast of telescoping tube to get a lighter top to the mast.
I would run your 54mm to say 1/2way,50 to 2/3 then the next size down to the top.
This should work nicely
Sounds good. I'll go with the larger 54mm tube to start with. So about 1/2 way up I'll have all three sizes inside of eachother, the next section will be the two smaller sizes inside of eachother, and at the top will be only the smallest size.
Thanks again for your help. I'll be ordering some parts shortly and put my land yacht back together again fixing my weak spots.
My buddy and I have already started designing a class 5 (like the PM) land yacht. I'll post some pictures as we progress.
Terry
if you get the chance have a look at a FED 5 before you build. they are a good design also and possibly easier to build. i would be strting with 4.00x8 rim wheels,rather than trying to go high tech from the start.
remember to enjoy the whole process from design to roll out, and dont get tooooo serious about it all
cheers Paul
The Fed 5 looks very similar to the PM, but that may just be my untrained eye. I've studied the PM plans pretty well and understand how to build the drop axle. Is that the main difference? I read that you recommend a 5 deg angle if sailing on salt and 10 deg if on sand. The plan shows 7 deg. if I am looking at it correctly.
I will most likely use the new simplified steering you showed in some photos set at 30 deg. Looks like you didn't narrow the main beam with the new steering setup. I liked this better, it looks stronger.
Still don't 100% understand the Mast Step. Is this designed so the mast can be inserted at different angles? And the locking T can be inserted between the 5/16" rods at different locations depending on the angle of the mast? It may eventually come to me. I just need to stare at it a bit more.
One more question. What keeps the rear wheel clamps from twisting on the axle after they have been pinched down. Is pinching them down enough? There is mention about an axle retaining slot. I beleive this is the slot cut out so the tube that the axle slips into can be clamped. But I may be missing somthing because I don't quite understand when it says to rotate axle front to back to lock axle in.
Anyway, sorry to bombard you with all the questions. I've been looking at the plans while typing this message and things are popping into my head.
We've stuck with the 4x8 wheelbarrow tires and 5/8 sealed bearings with our kite buggy and land yacht so far. Though the last ones I purchased for the land yacht the rims were very out of round. I need to find a better supplier without spending an arm and a leg.
I do most of the machine work, such as the welding, cnc machining, tube bending, etc.. My buddy I build with is very artistic and great with wood, and fiberglass. We like a challenge and now that we have a little better idea of what we are doing I think this next build will be a lot of fun.
Terry
Excellent, keep us posted with lots of pics!! 
you could PM Dave Webster on here, he had some high quality alloy wheels in stock not long ago.
I think the mast step on the fed 5 is a better way of tackling the changing mast angle scenario.
the rear axles on the PM had a slot cut into one end that resembled a light socket fitting. you could drop into place and then rotate the axle to get the right spot. THEN you tighten the clamp.
Keep an eye on the 5/8 axles as weve found that there is a tendency to snap if subjected to lots of vibration on a cl5 eg claypans
Got it. The axle drawing that shows the 3/8" hole (with additional material removed) on the left of the page now makes sense. This would also keep them from rotating after they have been clamped. We may also consider welding the axle clamp to the rear axle and going with a steel axle. Weight would increase, but this may not be a problem for us.
Good to know on the 5/8 axles. Is this mostly in the rear or have you had any problem in the front. If we design or own rear wheels we can go to a 3/4" axle.
I'll have to research te Fed5 mast design some more. I wish I could look at one in person, but the internet is my only means right now. Maybe I can find an up close picture.
Thanks,
Terry
I'm using steel axles these days as the Ally become harder to get.. 3/4 would be better. You may get some good photos on the NALSA website as the US has the biggest fleet of FED 5's
Just a thought on class 5 mast design, has anyone tried a rotating round mast with a fixed boom. So instead of the boom moving around the mast, the whole mast and boom and sail would rotate as one?
I know wing masts people have used rotate and the boom moves inderpendent to the mast.
This is how I set up the mast on my land sailer. The boom is mounted solid to the mast and rotates with the mast. It worked really nice (until the weak fiberglass mast broke). When I replace my mast with a proper aluminum mast, I will set it up the same way. I used a simple clamp method like they use on windsurfers.
Though on our next land sailer we build I will probably have a fixed mast and let the boom and sail rotate on the mast. I'd like to try both ways to see what the difference is.
Oh well never mind 
at least that saves a few hours on the CAD program.
BUT I will keep the idea for a class 6
