Equilibrium rig,how its done at the bottom of the earth.

Many of you will know that I have been experimenting with a form of balanced una rig for Footy class yachts and other even smaller yachts for a couple of years now.
I have built around 20 of these rigs now and have refined the concept into a inexpensive,light weight,easily built automatic gust response unit.

Many when they first see this rig dimiss it for a whole lot of reasons,mainly because it doesn’t look like anything that has been sucessful before.
But beneath the odd looks is some solid reasons and the performance of the rig seems quite outstanding when compared to more"normal" looking rigs.

I will make this a Q and A type thread I think.
I will post some pictures of the rig and will attempt to answer your questions about it.

Ian,Can you please post your photos of the boat and rig…I am much too thick to manage it.

Really looking forard to this Brett! Thanks for taking some time to educate us

Well it is only one mans idea of what to put above a footy hull.

What do we want in a rig anyway?
something to hold some sails up and a way of coaxing the sails into the shape needed for best forward propulsion.

As lightweight as possible is always good, quickly made would be good,Ive spent hours making rigs in the past.

a rig that can be quickly exchanged for another between races.

Heres a bit about my “solution”

In broad terms it is a swing rig without a mast and a solid forestay!
a single sail is set on the forestay and the whole rig pivots around a point where the mast ought to be.

The Forestay( refered to as the mast from now on) is angled back to give quite a rake, the mast is made from 3mm carbon tube in the current version.
The boom is made from 1.5mm carbon rod and there is a Z shaped peice of s/s wire (1.5mm)connected the two together.

The Z shaped wire starts at the bottom of the hull and is sharpened in order to pivot easily.it comes up through a small peice of brass tube glued through the deck.
As the wire exits the deck it is bent and goes forward 100mm in my case,it is then bent upwards for the carbon tube to sit over as the mast step.

The carbon rod boom is glued onto the bent wire and carbon tows added to taste,the ammount of carbon has a direct bearing on how much the rig is allowed to twist.

Footys are very short and differcult to handle,this rig solves many handling problems as it smooths out the variations in the breeze that the boat is feeling.These things happen so fast on small boats that it is impossible to react to them so the rig must be automatic. The latest versions can sail downwind without diving at all,the rig absorbs the power from the gusts and returns the power to the boat when the gusts ease.
You get extra power at the end of gusts as the rig comes upright again.

The hardest part is matching the hull/keel to the flexibility of the rig.
The size of the wire and ammount of carbon tow can be varied to get as little or as much stiffness as required.

OK…as you will have picked up it is the bent wire twisting that depowers the rig,not mast bend.I would like to have some mast bend as well but havn’t been able to match the sails to the mast well enough at this size yet.

Since the mast isn’t bending making the sail is quite straight forward.
I use a simple one peice pocket luff sail made from Florist film.
The Florist film is cheap and stiff enough not to need battens,you could use lighter materials but this stuff sets up in a nice smooth shape easily.
The sail is simply taped to the ttop of the mast,gravity holds it down without need for a downhaul.The stiffness of the pocket luff makes sure the sail will not ride up the mast under pressure.
The outhaul is simple another peice of tape holding the sail to the boom,by varying the position of these 2 peices of tape(mast and boom) you can vary the twist and camber in the sail(honestly:))
The mainsheet simply hooks over the bent wire before stepping the mast.
Changing to a smaller rig means steping the new mast on the boom and taping the sail into position.Really keen guys will have multiple booms/sails etc.
The last peice of the rig is a small counter weight on the end of the boom to balance the rig perfectly.

The rig pivot allows the CE to be more or less above the boat for downwind work,the offset pivot also reduces sheet loads enabling the use of a lighter than normal sail winch.
You can see the mast bend off at the bottom as gusts hit the boat,the boom also bends opening up the leech,as the gust eases the rig comes upright again giving back the energy.This automatic gust response smooths out the handling of small boats a treat,the boat will sail upwind completely hands off giving the sailor more tome to think about more important things on the racetrack,This may not be the fastest rig in absolute terms but freeing up the sailors mind for other duties makes the overall package very competitive.

The whole rig incl sail can be made in about half and hour.
I will give some dimensions and angles in a latter post.

Here are a couple of photos as requested. Details and photos on the construction of what I prefer to call the “DUNEDIN RIG” will be posted shortly.

I can hear the wheels turning all over Footydom … kudos Brett


Great post, Brett, and thanks, Ian for the additional pics…Dunedin rig, huh? :slight_smile:

In addition to the excellent info Brett already posted, he has told me that thread soaked with CA glue will work to attach the boom, but won’t be as stiff as using carbon tows.

Also, he suggests the balance should be about 1/3 in front and 2/3 behind the pivot point of the sail.

I hope to get one made and try it this weekend…provided this snow/rain/ice storm ends and the weather improves by then!


p.s. Brett didn’t mention the need for something firm under that pivot…I can just imagine my mast drilling a hole throught the bottom of my boat!!

p.p.s. Who are those ugly guys holding those beautiful boats??

Bill, If you first put a short piece of brass tube onto the pivot before stepping, it would keep the end of the wire from touching the bottom of the boat. Just as long as you keep the bent part of the wire from rubbing the pivot tube.

What exactly are carbon tows?

I believe those two distinguished gentlement in the photo are from NZAPAS (New Zealand Association of Pint-drinkers And Sailors)

Carbon fiber filaments which are not woven into cloth. This stuff is carbon tows with a very light backing which allows the tows to be ironed on (otherwise, the unmounted tows don’t like to stay where they’re put much).

Ha, don’t fall for it Bill! It’s a Kiwi plot to sink our boats before we can get course times recorded. :stuck_out_tongue:

Seriously, I’m going to give it a try but not until after I get past the Postal Classic. I have my rig working reasonably well and I’ll stick to what I know. A more experienced skipper might be able to make radical changes quickly, but not me.

Did you notice the long arm on the sailwinch? It looks a little long, but I assume it’s the right length to allow the boom to swing out for downwind sailing. There looks like a micro servo on the end of it too.

Also notice the split pin on the bow point where the sheet goes through; not your usual fairlead spot.

And the big question: where do Yanks get 2mm stainless steel wire? DIY?


you can get stainless steel, and titanium 2mm, and 2.5mm spokes from a quality bicycle shop. stick with “dt swiss”.
the mushroom/ bent part is also good for passing through a servo(std size) horn, instead of z-bends.

Duh! I have boxes of DT spokes, both round and elliptical. :smiley:

“Quality cycling shops” went away with the 80’s…


I keep on looking at this thing with amazement. If it performs as well as it probably will, it is the greatest advance in yacht rigs (model or full size) since the Finn dinghy with its bendy mast in 1951. So far as I am aware, it is the first model rig that will depower completly automatically without all kinds of gimmicks and gixmos. This in itself totally rewrites the book on Footy hull design - I’m not sure how.

Congratulations Brett. You have out-thought me and evryone else. ‘Official’ terms seldom catch on. I shall be addding the McCormack rig to the Barber hauler, the Cunningham hole and the Elvstrom bailer in my list of eponyms.

Cheers mate, and very well done.

Those of us who don’t commit bicycle can get lots of stainless, small hardware, Teflon, Delrin, and all kinds of other neat stuff at Small Parts Inc.. I’ve found them to be a great resource.


Here are the first of my photo`s in the “how to” section of this “McRig” thread.

  1. Shows the layout for the bent wire base. 50mm = 2 inches (near enough)

  2. Wire blank bent to shape.

  3. An earlier version wrapped with Kevlar thread and glued with five minute epoxy. (More photo`s of this process soon.)
    (The boom here is a carbon fly rod tip.)

  4. Fitted up with a mast and sail.

I have ordered some more carbon bits and when they arrive tommorow or the next day I will finish the rig I am building for Nigel and post pictures of the process.

Do you think you could either drill a hole in the boom for the axle, or maybe a shallow groove for the wire to fit into? You could probably eliminate most or all of the wrapping by using a 3mm tube for the boom, and putting the wire in a slot, and filling the tube with epoxy.

BTW- in the U.S., we can get #4 pushrods in chrome/zinc steel, commonly from the hobby stores, and they are probably 2.5mm heavy. I keep a stock of those for the power boats, and the bigger yachts. It’ll be a little less bendy, but a little stronger too.

Yes Tomo I am sure there will be many derivations as you suggest, as the combined might of the brain power of the FOOTY community puts their head around the concept.

Suck it and see would be my advise, then post your findings here for us all to benefit from your experiments and knowledge.

thanks Ian.

A few things to note.
The flexibility of the rig has to be carefully matched to your hull and keel package.
It will take some experimentation to find the sweet spot of having sufficent power and smooth gust response.
The sizes of the parts I used are tailored to a 500g overall displacment for reference.

The sharpened end of the wire sits into a quite large diameter peice of tube glued to the hull bottom with a small peice of timber between it and the hull.,it doesn’t just pivot on the hull bottom. The through deck tube and this bottom pivot must be very free moving.You should be able to blow across the room and the rig should move.

Also make sure to angle the boom upwards somewhat…it will drag in the water when hard pressed on a reach if you don’t.

Sloops,schooners and ketches are possible with this style of rig also.

Thanks for sharing Brett. I’m very keen to have a go at this type of rig too. Most of my questions have been very well answered and all I need to do now is get my hull ready…