02 March, 2020

Improvement in Wave Propulsion Devices: Using the power of the sea waves to create forward motion in a boat.

Following, a transcription from my article in Catalyst N-44 from October 2011:

I have never calculated how much a wave weighs; I suppose this can be measured in tons. And all that water in motion almost all the time: tides, currents, waves; also the wind generates motion of water and interacts with it affecting floating objects. Normally, we accept that if something is possible, somebody else did it long time ago: oars and sails was used for centuries by our ancestors before engines came on the scene. But after new materials were invented, all of that was improved, as seen in the world of sailing and rowing. Today the wind can be tracked at a smaller angle and several persons have crossed the Atlantic rowing. Now, I was an enthusiast of sculling oars, because this is a very simple and relaxing way to propel a boat, fitting to a minimalist mind like mine; but at the same time I am still researching about the possibility to propel a boat using the waves. I love the lines of powerboats but I don’t like to depend on petrol and at current prices I think most of people are looking at their budget. Now, after researching in the net, magazines and some books about the boat propulsion, I have seen several models that are not capable of working with beam seas, others that produce more drag than desirable, and most of them a multi-complication of springs, monstrosity of floats, fitted in expensive boats and developed by engineers. So I like to go back, to trial and error and to the old technologies, I suppose that somewhere, somebody used to sail across the waves with timber, cord, and after observation of nature and some experience rowing. So, looking at the different kind of oars, from the paddle to the ro, I saw that the last one, like the yuloh and western sculling, uses hydrodynamic lift. Most of us know the modern propellers uses a similar motion to sculling, so the matter is to do sculling faster. In pursuit of that idea, I made a sculling oar, changing the horizontal blade to a vertical one. This decision was looking for a blade -or propulser- with less drag, capable of using the rolling of the boat. I liked to begin with something at least a bit proven, so I began with the fishtail oar made by Douglas Martin as seen in the Small Boat Journal, Nº46 in an article by Ben Fuller, curator at Mystic Museum. I made it in plywood and pvc pieces, changing the profile but maintaining length and proportions. What I did then was to fix it to the transom of the boat, at 30º approximately, with an universal joint, and from the flexible tube of the loom fitted one lanyard (elastic as well) attached to the center of the boat and parallel to the keel. It didn’t work, if the current was from one side, the blade went to the other and stayed there. Conclusion: too much flexion. I needed something more rigid, and supposing my idea to be too stupid I left it for a long time. A big disillusion, and throw away the “device” (bad idea, the paddle was a very good shape and improve the initial model). Then, as ever with the idea to save some petrol, I decided to do a yuloh. I received a lot of help from Douglas Brooks who sent me his article “A Different Way to Ro”, and was very enthusiastic about my project. After reading Catalyst Nº34 I contact Slieve MacGalliard, and his study of yulohs was a great help in looking for proportions. Mike Bedwell contacted me, after seeing in my blog the plans for a yuloh that Bob Hollis sent to me from Australia, and his opinion that the use of his device in rough water is possible was a big help as well. The first benefit of my work – if I can call this work – is to show that fellow sailors are reliable, at least most of them. Chuck Lumweiber from Duckworks was also very kindly, as was Simon Fishwick, editor of this magazine. So, at the end of all this research, and after some study of internet forums and writings, my ro results in a very efficient way to propel a boat, faster than 3 knots for a long time, and capable in rough waters, mostly after improving the universal joint at the fulcrum. But I was not taking in account, at least consciously, was this: the selftending characteristics of my ro-yuloh hybrid (like most sculling oars of this kind) was capable to propel the boat in the waves with less effort than in the calm. So I went back to the old idea. I took an old wooden oar, like 4 feet of paddle, and after cutting out the rot I carved it with my precious knife to a vertical profile. This results in something like a rudder, or fin, or hydrofoil, call it whatever you like, narrowed from 4" at the waterline to 6" at the tip of the blade (where is the balance point); this with a loom something like 5' long. From the balance point to the stern – where I made a universal joint – I left a bit more than 2' (or where this thing balanced leaving it at 30º from the stem to the water, with 3/4 of loom immersed). And from the upper side of the extremity of the loom I attached it to the deck with a lanyard, at an angle bigger than any yuloh. With this thing on the back of my boat I was capable sculling in the calm, not efficiently as the ro I mentioned before, but capable of 3 knots with a little, but noticeable, effort. In the chop this was working differently: I needed just to steer with that lanyard or by holding the loom. With beam seas this works as well as with head or stern seas (talking about speed and efficiency), and the skipper need to learn again how to sail. He needs to manage the waves, the wind and tides, developing some intuition or sensitivity. The speed was not too reliable yet, at least to propel my 20' and 1000 pounds cuddy cabin craft. An important matter to note is that the fin doesn’t moves through a big angle, probably only 5 degrees to each side, and that after the top speed is reached, it is capable of maintaining it, and it gives regular drive, not varying from wave to wave or when steering (that is when using the lanyard, not when handling the loom). So, I was thinking in how to increase the speed, studying to do a bigger fin using plywood and pvc inserted in a rigid wooden stick. But this is not the solution; because the bigger is the fin the slower is the motion, just the horsepower is supposed to increase. Then I remember a short interview somebody did with Ken Upton. I read it a couple years ago when I began to study about the possibility of wave propulsion, but my memory didn’t help me much, but Ken was telling the journalist that if an small fin is positioned a bit before the main one, this will increase the power and efficiency of a water power generator he developed. I can’t mention the books I was reading about, but I remember a Japanese engineer telling that some modifications in the hull can produce redirection of the water motion to the rear, without movable fins.
The solution I found was to add something like a step in the stern, under the flotation line and raising the bottom level, horizontal or parallel to the keel. The size is 3' long – where fitted – and 6" wide. With this – I think doesn’t work like stabilizer or flap– the boat can move by itself if somebody is skipping or rocking on the deck. The result was a good improvement in speed, and improvement of displacement of my planing hull without any significant wake (anyway my multichine boat was producing just a bit of it). So I think the last addition can help to make a multipurpose hull, capable of efficient displacement, semidisplacement and planing. The surprise comes after some time using the total wave propulsion system:- in some conditions the rudder – oar, fin or whatever – is cavitating slightly and the boat tries to go faster. Another important thing important to note is that the rolling and pitching sensibly diminish, obviously converting into forwards propulsion. Finalising my brief description of the system, I will say that when I build the hull I made some modifications to it, thinking about the matter that the Japanese engineer I mentioned above says about the wave propulsion. In the first third of the bottom, just in the middle of the curve from amidships to the bow, I converted the flat to a certain concavity of one inch deep from side to keel. And being all flat to the transom, the last two feet or so I made a bit rockered, something like five to ten degrees. I was a bit diffident doing it, because a hull is forever, but I suppose it is better it be more pronounced. Finally: apart from the necessary rudder, the whole has no movable parts. I don’t know any more than it is important to take into consideration the water flow, vortices, wind, tidal and currents, waves and friction, pendular motion, or more variables working together to make this hull efficient. It could be better, but in that case a deeper study and associated proofs are needed. I hope to do it, but at moment the hull’s bottom is still a bit dirty, and I am working with scrap and dollar shop materials. While I don’t know the future, I can share all this at this moment, with the intention to be at least interesting. My intention was ever to make a system with minimum drag, simpler than any engine or sail rig, efficient in most conditions, cheap and reliable, light, easy to clean and repair, without floats, elastics, springs, etc: different from everything I have seen before.
Now I am still living onboard, in the bay outside the harbour, and intending to leave this place (36º44’45" N, 6º25’35" W). But we will see what happens, if in October or later I can cross Gibraltar or Vizcaya Bay; if not, I don’t know. If somebody is interested to apply this concept to his boat – planing or displacement with several differences – feel free to contact me to my e-mail or blog (this will be realised soon, I think promptly after this article appears); the same if somebody is interested to apply it scientifically and/or commercially.

Note: Thanks to Douglas Brooks http:// thesabaniproject.blogspot.com/ to help by sending me his article about japanese ro oar.

In the images can be seen how the system works. All the rolling and pitching motion is redirected to be a horizontal and forward thrust. In a calm, the rudder acts like an oar, or to accelerate the boat under various conditions. Under ideal conditions, five to six knots can be achieved, and this is about the speed hull limit. I did several miles using it, trying and experimenting, changing shapes and correcting errors. If good research is done, I think better results can be achieved to make this a primary propulsion system for any boat. Another thing is that all of the drawbacks for a planing hull when trolling, result this way in a benefit. We need the motion of water, eddies, turbulence, etc. and convert it into propulsion. Anybody can feel free to contact me and exchange opinions about the useof this in any kind of hull.



28 February, 2013

Rio de la Plata conditions.

Before I began to talk about the new design is good to explain how are the water condition where I living. "Rio de la Plata" means a river of silver and this name is related to the expediotions of conquistadores from Spain. This is the bigger estuary around the world and the conditions can be worst than in the ocean, a couple of weeks ago in summer we get waves of five feet with a period of five seconds and strong winds. "Pampero" from the west or "sudestada" from southeast normally comes with no warning, are too strong, and normally produces big changes in water deepness.
Talking about the last- we got from five to fiveteen meters of water, so is very normal to sail in breaking waves. Most of the fishermen use a dory hull, in cedar but sometimes they drown in the surf near the shore.

27 February, 2013


NA-Y boat results very seaworthy. I can't post a pic about but I seen this boat floating over a two meters breacking wave in the surf a day when the swell was very strong.  The boat was very light and the water flows down the chines. Once I sculled her in open waters when the ferryes still at dock.
You can believe or not, is up to you.
Yulohing it is a bit slow but not very hard, I remember that day I mentioned before, the waves was something like six feet from the stern cause the wind, and also six feet from starboard cause the tidal. The yuloh I did based upon similar proportions of Slieve Mc.Galliard suggest works fine in the waves- also over the wake of the ferrys as I a bit scared tested several days ago- .
The only problem with the NA-Y was crossed winds. The next hull will need something like leeboards or chine runners. I think Yrvind's development is special for this kind of boat- but will need modifications to use it in assist the wave propulsion (something similar to to chine runners is mentioned in Gardner dory's book).
The wide stern from the original planning hull was a good choice. In a multichine boat light as this the water will flow very good to the exit with no need of a narrower buttock when doesn't have the weight of the engine hanged in the stern.
After I discarded the engine I did the yuloh from scrap. The main arm- paddle and longer loom- comes from an old whales boat oar in red hard wood -"platanillo" in spanish- with the addition of a smaller arm at twenty degrees or so. Works well as I tell above - but better can be a development of a vertical blade as I did in my first draws (mi first attempt was a vertical blade and was better- two to three years before but was stonlen) and this also can be used in automatic position when sailing in good waves.

I tested an small sail but is not necessary except in conditions of wind with not waves- something difficult to found at sea. In my next hull I will consider all the boat as a sail to take advantage of the wind. This sail is the orange thing you can see over the deck - folding mast-.

26 February, 2013


First of all, I'm not an expert, but I got enough knowledge to say some people around still exagerating about the difficult to do a floating thing. With patience, some skills and tools is possible to do a boat. If you got the plans a some assesment is not impossible.


This is the better history of marine wave propulsion I found in the web. By clicking in this link you will found a well registry of the background of this thecnology. Click here.