In hindsight the wing on the berminator should have been a bit larger but it was a fun project.

Not the "Playa-ground"

Since the rules allow any size or type of tire wheel combination I am converting my yacht to accept 16" Skyway Graphite BMX bike wheels and smooth Kenda 100psi tires. The durability of the tire/wheel combo is the ticket. Less drag, less weight and less expensive than any 8" wheel/tire combo.

The Jr. dragster wheels that desertyank is using are pretty sweet and look awesome but kind of over the top and heavier, with a larger patch on the ground creating more drag. In comparing two US 6.7 yachts this weekend at Delamar dry lake, it was obvious that the skinnier, taller and lighter FED 5 BMX wheels and tires out performed the wider, shorter and heavier Airtrack wheels and tires.

These combos were both run on a dry lake but I'm sure the 8"ers would uot run the 16"ers on the beach or dirt.

Original FED 5 converted to a US 6.7 mini. Hauls ass!
The FED 5 has a unique rigging that is very efficient and has less wind drag and is highly adjustable.
Check out that mast step


An original Airtrack promo converted to a US 6.7 mini. Hauls ass too!
The Airtrack uses a conventional center pull rigging.



My next build will be a US 6.7 mini.

Delamar is approx 100 miles NE of Vegas.

www.google.com/maps/@37.3127,-114.951153,6801m/data=!3m1!1e3

Between the island and the shore is approx 5/8mi

Front of chassis before BMX front end conversion.


And I was'nt even done adding parts!

From 8" wheel to 16" wheel rear axle conversion pics.

Before the change.


After the change



Done


If anyone wants to see a drawing of the procedure, send me a pm and I will post it.

these are the parts I made for the front end conversion.

The mast step tube is 2.375"od x .125 wall. 18" long. It will be capped on the bottom end.

The spine extension is 2x2sq tube .125 wall. It has a 1.1875 radius at ten degrees cut into one end. This is where the mast step tube welds to and gets a 1.0"x.125 reinforcing strap wrapped around it and extends down the sides of the spine.

The head tube neck has a radius like the spine and a 1.3" through hole bored .25" back from end and at 90 degrees.

The head tube is made from 1" stainless pipe 3.5" long and partially bored on the ends to accept the head race cups. The caged head bearings were replaced with loose ball bearings. 25 bearings in each cup rather than 16 bearings in the caged bearings. VERY SMOOTH! and more support from the bearings.

Parts used

W/BMX front end

Mocked up

Steering parts

I have a couple of Um I wonder thoughts
I like what you are building here but I wonder about those rear wheels and I wonder about that square section spine
Round tube is much better in torsion and thats what the spine will get Square tube will need to be bigger than round to cope
I guess you could test it by getting a fat buddy to sit on one rear wheel and try and lift him off the ground by a lever in the mast step
Rear wheels on landyachts get a lot of side load and bike wheels dont get that in their normal life
They are just OK on the front but usually only with layover steering
Just saying IMHO

Just my few cents worth.
I have built well over 100 landyachts. The lightest class 5 was 38 lbs with mast but no sail, and it was a complete pig. When I added weight it just got better and better. I don't honestly think that they need to be much less than 50kg. I have loads of theories, and have sailed in every continent except South America somewhat competitively in every class except Mini 5.6. I am always happy to see people try "new" ideas and see if they can make them work when others could not. :)
That mast/front fork system is going to apply massive torsional loads to the front wheel IMHO. I think that you will find the front wheel will be leaning over the moment that wind loads come into play. Happy to be shown to be wrong though.

kiwi307 said...
Just my few cents worth.
I have built well over 100 landyachts. The lightest class 5 was 38 lbs with mast but no sail, and it was a complete pig. When I added weight it just got better and better. I don't honestly think that they need to be much less than 50kg. I have loads of theories, and have sailed in every continent except South America somewhat competitively in every class except Mini 5.6. I am always happy to see people try "new" ideas and see if they can make them work when others could not. :)
That mast/front fork system is going to apply massive torsional loads to the front wheel IMHO. I think that you will find the front wheel will be leaning over the moment that wind loads come into play. Happy to be shown to be wrong though.

I'm sure you know a lot more about it all than I do but I gotta try it. They have been proven and I'm willing to do whatever it takes to get an edge up.

I weigh in at 250 pounds, I don't think I will have a problem with having to add weight.

Thanks for the vote!

the big issue you will face with the 16" rears is that you wont have a big enough contact patch for traction. the simply slide out from under you under side loads.
particularly treacherous in wet or soft conditions.
the tyre wear is horrendous.
i had an early mini fitted with the same tyre, and it was unraceable. that was back when we were sailing with 3m rigs too!!!!

I think I'm going to make a bushing to be able to switch to the 8" wheels, if there is an issue. the dimensions will be: 1.0"od X .625id X 3.0"L .375 wall

Some new build info....

Based on some other builders comments and recommendations I went ahead and fitted 10" Azusa mini bike wheels to the rear. These will serve as my back up set as I will be giving the 16" re-enforced wheels a go first.

With the street tires installed on the 10" wheels the diameter is the same as the 16" hookworms. My chassis geometry will not change but my wheelbase does with the wider wheel due to a wider hub. It is still inside the rope!


Azusa 10151 10" mini bike wheel

Mounted to axle.

Inside view

Tire I ordered
Kenda K329 2.50-10

Steering pivot point

I started with a FREE set of atomlab mountain bike platform pedals. I chose these because they have a square center section and replaceable sealed bearings and are made of aluminum.



I cut off the platforms and machined some height adjustment slots in one of the faces
I also machined the sides where the platforms were. As you can see the factory castings were less than perfect. In fear of cutting too deep and ending up in the pedal shaft bore I left them alone.


I then machined a mount out of the left over 1" axle shaft's. They were drilled and tapped to fit the original pedal shaft threads. 9/16-20.
This will be welded directly to the chassis spine


My steering pedal shaft will mount wit two 1/4" U bolts with a fabricated aluminum backing plate.

Here is the mock up