The YAGO Project
designing & building a 31’ Steel Origami Yawl

design by Gerd Müller

Chuck was so kind as to allow me to present my YAGO Project here, and I am more than happy to do so. This is just a short intro, for more detail and contact you should then go to YAGO’s website at:

YAGO is a 31 foot steel yawl, and quite unusual in several ways, for its general concept, for the construction method and finally for the way the plans will be distributed.

The Concept

I did not really want to build a boat again, I had been there before and left a good part of my life and health building 4 steel boats, plus several smaller stitch & glue ply projects, helped on numerous other projects in WEST, Ferro, C-flex and you name it, and anyway thought I was far too old and lazy to really get drawn into this again.

It’s just that my wife kept pushing me to start the final voyaging boat I had always promised her. Well, guys, there are wives like that, don’t be jealous… ;-)

I had kept the plans for a 37 footer tucked away nice and warm in a drawer, for many years, and always found excuses not to start. Then by accident I came across the ORIGAMI building method (more on that later), and right away understood that that was completely different from everything I had done before. I was flabbergasted (always wanted an opportunity to place that word somewhere…) and simply did not believe what I read. By the time I understood better it was to late, I absolutely had to try this out myself, and started making first sketches.

As I had become a bit wiser but not any richer over the years, I wanted to design a boat that would allow me to start right away, from next to nothing, and to be able to finish it, so to say, from the running pocket money budget, but at the same time be well capable of taking me almost anywhere in enough comfort to live aboard for many months. So the first thing was that I reduced the size to about 9 m, and the second was that I switched from a modern rig with fully battened main to a traditional gaff rig. At the same time I did not want to give up on the modern hull shape and wanted absolutely to keep the daggerboards. The result after some weeks of doodling and then more serious CAD work looked like this:

As you can see, YAGO has quite traditional topsides, not really classic but let’s say what went for “modern” in the forties and fifties. Together with the Rig this gives to my eyes a pleasing look that does give no indication of what is below the waterline. A more classic deck, with a coach roof could also be designed of course.

The hull shape is a rounded chine hull (see below) where the chines are under the waterline. There are 2 chines, plus a very light central V. The hull has a very modern U section with nice entry and fairly flat exit, all inside ballast and with the possibility to lift both boards up when running a very low wetted area and good speed potential.

The Daggerboards are a bit unusual today, but they have lots of advantages. They are made from ply covered with glass-epoxy and slide up through the deck. On longer tacks you would lift the one to windward, but in confined areas you just leave them both down. They can be lifted with simple block and tackle, they can be removed easily for cleaning, they can even be switched if one should be damaged, there are no axis or mechanisms to jam or to maintain… and of course they let you beach your boat and get into all the quiet moorings nobody else will get into.

YAGO is a gaff yawl. To be honest, the real reason is that I just love the looks of it, although I have sailed smaller boats with a similar rig and came to appreciate it. A cutter would fit just as well and it would be no great thing to modify that. Otherwise the obvious advantage of the gaff rig is that there is no expensive hardware to buy, all can be made from raw material at low cost, including the sails if need be.

With the steel construction and the home-made gaff rig and sail, two major cost factors in a boat are taken care of. After that it is very much a question of personal choices and preferences, but YAGO can be a very low-budget blue-water sailor on the water without ever looking cheap, and with a bit of love and patience in fitting the insides and during the finishing stages should be quite an eye catcher.

The full width cabin gives a lot of volume inside, and as the steel hull will support itself without the need for structural bulkheads, the layout can be freely designed as fits best for your cruising program. I am still playing around with different variations, here is just one simple example, pretty close to what is today’s standard on this size of boat:


To make this clear right away, folded steel or “origami” is not new and of course not mine. This particular type of folding described here with darts from the center has been promoted notably by BRENT SWAIN who has designed many boats that have made extensive voyages over the past 2 decades. His book “Origami Boatbuilding – a heretics guide”, plans for his boats from 26 to 40 feet, books and a bunch of very nice and helpful builders you will find at:

In conventional steel-boatbuilding you will first set up a heavy solid jig, then build your frames and hang them, then put your stringers on and so on and finally plate this structure with what will be “the Hull”. Believe me, you will spend a lot of time and cash just shopping and driving around and working before you even touch the first piece of steel that will actually remain in the hull.

In Origami the process is inverted, you will first build the skin, and then simply insert the structure where necessary. To do so you will cut a single shape per half-hull out of a flat sheet of steel and then pull it together along the seams, a little bit like in stitch & glue cosntruction, to produce a 3-dimensional half-shell. These two halves are then joined along the centerline.

As a picture is worth more than…. Here is the shape for YAGO:

You can save the picture on your computer, scale it up, print on paper and try it out yourself. The upper shape is the theoretical , flat half deck, without camber, you need this to define the sheerline.

Here is how to do it in steel:

Cut the same shapes out of full size panels, flat on the ground. Then start pulling them together:

The pulling, although quite impressive, is very easy, done with cheap $8 come-alongs.

Here you can see the starboard half in front, and in the background the port side coming together.

Once you have your 2 halves you simply join them along the centerline and pull the hull together:

Compared to traditional construction this is incredibly simple, cheap, surprisingly precise and most of all it is so FAST the neighbours still haven’t noticed it yet ;-)

I have knocked the hull for Yago together in 8 working days over a handful of weekends, under bad conditions and only with my 14 year old son, and I had to assemble the full size sheets first. The total amount of money invested at this point is about 2000 US, half for steel and half for tools. If you can get single full size sheets, the hull should come together in 3 days. If you have ever built a steel boat, just think what you will NOT have to do:

  • No Scrap hunting for the jig
  • No jig to build
  • Frames fitted in later
  • No turning of the hull
  • Much less cutting, welding, grinding
  • Not hard points during plating
  • No lifting of plates as they are always supported o the ground

And finally, you get a very sweet round shape that you simply can not have with normal hard-chine construction.

The secret lies in the fact that the steel can take a “natural” shape and tension, without being forced and welded to a rigid structure. Because of the way the darts are cut, the hull will produce rounded, compound sections for and aft, the chines will only remain in the central part and under water. An Origami hull in the water looks absolutely like a round-section hull.

In the picture below, you can easily see the foreward end of the chine and the way the plating will bend into a compound surface.

Once the hull is assembled, you add the deck, which will define the sheerline.

Only AFTER that you will go inside and add the structure as required by the designer.

A note on “Frameless”: Origami is often described as frameless steel construction. This is a bit misleading. What it really means is that frames are not required for the assembly, and you may freely place them afterwards for best efficiency, and simply by cutting pieces of profile to size and fitting them in. It does not mean that origami-boats automatically have no frames, it just so happens that some designers like Brent Swain design boats without frames, or with few frames, whereas YAGO for example does have frames.

If you want to see more about the way you would design an origami hull or to convert an existing hard-chine hull, the full CAD process is described on my website:


There is not only the design process explained on my site, there will be all the rest as well: YAGO 31 will be distributed a bit like “open source” or “freeware”. There will be all plans freely available. At this moment I am working on a full building manual with pictures and drawings, and the first part, for the hull, should be ready for download September 2004.

Already now there are a few people gearing up to build their own YAGOs, and I hope that over the winter 2004/5 this will begin for real. There are requests for different layout, rigs, even hulls.. I might not be able to do all that myself, but you know, the more fools there are the funnier it gets.
For my own boat, I hope to be ready for sandblasting and painting spring 2005, and in the water a year later, have quite a busy professional life to attend to and working only over the weekends and some odd hours in the evenings.

So, if it is so easy, fast and cheap to build such a nice boat, and if even the plans are free for the taking, there is really no excuse anymore NOT to start building your boat tomorrow – so what are you waiting for?? ;-)