Entries | Contributions

A Proa for Ariadne

On the Greek island of Naxos, fabled home of Dionysus and Ariadne, Helmut Mueller is building an 8 meter proa. Unusually for its size, it is actually a half-displacement model of a 10 meter proa Helmut intends to build. However, we decided it was best to build the 8 meter model first and test it thoroughly. Besides being a lot of fun, the 10 M proa is intended to be practical transportation between the islands of the Cyclades, with the ability to carry several hundred kg of cargo- so it needs to work, and work well.

This proa is laid out along the general lines of the Kiribati proas, with the famous “Kiribati dimple” in the lee side, and a 40 mm lateral camber to the keel. The only hydrodynamic innovation is the use of a “vortex tunnel” keel, which Dieter Shulz and John Dalziel developed some years ago, to get better windward speed from hulls without daggerboards. Dieter built and tested aerodynamic models which showed promising lift/drag characteristics, but as far as we know this will be the first full-size test of the concept.

continued...

Bamboo Boatbuilding

I held a sample of interior grade bamboo ply in my hand and it took less than two seconds to decide that I could build boats out of this stuff. I could not believe how light it was! And it felt about as stiff as steel. Of course it has to be completely incased in epoxy to be used in a marine application and the interior bamboo ply is not, but bamboo has a lot of merit, none the less.

continued...

Crab Claw Tests

These are qualitative studies of slender foils and leading edge vortices for sailing craft. The results of these experiments, suffering from improvised input and variable conditions were good enough to inspire further work but produced more questions than answers.

continued...

FreeShip Walap

I've found a way to force the freeware boat design softwareFreeship 2.6 to do proas, it may interest proafile readers.

The problem is that such programs assume that the port and starboard sides are mirror images of each other, so you can build a catamaran or a trimaran, but not a proa. Then I remembered that proas *are* symmetrical, only the axis of symmetry is turned 90 degrees.

The trick is simple: begin with the default design, and set the measures to say, 6 meters WIDE and 0.5 meter LONG. the hull will look weird at first, but once you move the control points around, it becomes pretty normal.

continued...

FatCat21

Just a few months back, our Proafile host, Michael Schacht, introduced a set of concept illustrations for a very nice, 23' Hawaiian flavored catamaran called, Manu Kai.

Michael's vision was at once elegant in the manner in which it honored traditionally styled Hawaiian sailing vessels and it provided a set of unique solutions for how to blend the traditional with the modern in boat design.

Below the text of the article in the section for comments was a note from the author about the difficulties of designing this type of hull for a plywood build style. Since I design a lot of boats for stitch and glue plywood construction, I was immediately curious as to just how far down the path of the Manu Kai I could actually go with a possible design from that material/technique.

continued...

Palindrome - a Land Proa

Three quarter view from windward side.
The craft travels toward upper right in this view.

The land proa was a mad last minute dash to the finish for 2 quarters worth of thesis work I did around "Joy Rides". The idea was to create unexpected experiences--things you had to try to understand. All of these were developed as working prototypes. The projects included:

continued...

High Performance Outrigger Pt. II

In September I had my contribution appear in Proafile regarding the design and construction of my tacking proa or more correctly, outrigger sailing craft. Since that article I have sailed my boat in the strongest wind conditions that I had taken it out thus far, around 18 to 20 knots. Apart from an impending structural failure in that the 50 mm aluminium tubes could not stand the rig load from the side stays and bent permanently beyond their pre-bent shape, it was very instructive at a design level for this type of craft.

continued...

High Performance Outrigger

After more than two decades sailing, designing and building sailboards including a six metre long tandem I decided to go back to my sailing roots, that is a Moth dinghy. However I needed a craft for two as my son has accompanied me on my sailing journey for the last 20 years. The other problem was that when I last sailed Australian Moths they were 1.3 metre wide scows, and now they are ultra narrow 30cm wide skiffs that are more stable lying on their side, capsized, than upright, sailing. However the modern Moth is the speed machine of the monohull sailing world.

continued...

A Bloody Fine First Day With a Crab Claw II

Bleeding while you are swimming is disarming and kind. What seems to be water dripping in my face is actually something horrific -- that it never stopped dripping should have clued me in, but I'm still pondering that nth dimensional paradigm. Somewhere a baby is crying. I know this sounds like a cliche because, in all the bad novels, as soon as something interesting happens, there is silence, and always, "Somewhere, a dog was barking." The thing about cliches is that they're true, they're the condensed wisdom of society, but we English professors never tell our students this.

The baby is crying, and they repeat, "Man, you're bleeding!" I say stupidly, "My foot's stuck." And it is. I'm floating in a pool of blood, my eyes are covered with a strange film that I later know was blood, and I'm drinking ounces of my blood, and it will continue for quite a while because I'm also tasting Plavix, a blood-thinner, one of my medications. Yet, I'm happy that I wore the life jacket today, because at least I'm floating while -- yes -- the Nutcracker Effect. I didn't have the words to respond better than "My foot is stuck," nor could Hollywood have scripted a more unbelievable plot.

continued...

A Bloody Fine First Day With a Crab-Claw I

My girlfriend tells the story about her father who saw someone waste a few hundred dollars on some unworkable scheme, and he wisely observed it had been money well spent because "how often can you get a lesson that lasts a life-time for just a few hundred bucks?" My own father, well, I think he would just stand there shaking his head, perhaps with a slight grin. I can picture the ghosts of both fellows making their observations on the day I became a True Proa Sailor. I wrote most of the following narrative (some edits came later) late at night in a blood-stained shirt, hospital pants, no underwear, and a forehead fastened back together with Krazy Glue (really). I will be spending money replacing various things that fell to lake-bottom, floated away, or was stolen by a shoreside vulture after the ambulance took me away -- go ahead, shake your head, grin: perhaps it will be money well-spent.

continued...

Page 1 of 2 pages  1 2 >