January 26, 2012

Liebigs law and Yrvind Ten

Liebigs law states that growth is controlled not by the total amount of resources available, but by the scarcest resource, the limiting factor.

In a similar way survival of a small boat in big ocean waves is controlled by the worst imaginable weather, not by sunny days.

The capacity of the solar panels and the battery bank has to be designed to cope with the longest periods of overcast weather.

For every aspect of the design of Yrvind Ten the worst conditions has to be taken into account.

As the planned voyage is to circumnavigate the world non-stop with a time span of one year the boat obviously cannot be made as light and fast as if she was to be intended for a coastal cruise of a few weeks.

I beg readers to take this into consideration when judging the planned boats weight and speed.

The lines drawing and most of the primarily calculations are now done. I am making two layer plywood for the 1:8 model of 0,7 mm veneer.

Regards Yrvind

January 17, 2012



Friday 13 this January was a bright day Niclas Mårdfelt CEO of SverigesTalare a Swedish film production company and speakers bureau called and announced that they would like to produce a documentary of my project. Here is how he describes his company:

SverigesTalare is a film production company and speakers bureau that will follow Mr. Sven Yrvind whole project. We will create documentaries and spread awareness of project Yrvind Ten. SverigesTalare has got great expertise in online media, lots of media contacts and can create marketing material for Yrvind´s public speeches and his website as well as produce internationally documentaries. Last year SverigesTalare produced 80 productions and as a production company has got in depth knowledge about small boats and adventure filmmaking. The production crew will work closely with Mr. Yrvind and make sure that the true Mr. Yrvind is captured. //Mr. Niclas Mårdfelt MD.

Mr Mårdfelt is not only a visionary but an adventurer in his own right. He has together with Rune Larsson rowed across the Atlantic and spent many a summer cruising the North Sea. He therefore knows a thing or two about small boats.
Sveriges Talare has already produced a short video that can be found on youtube under the heading “yrvind ten” Hopefully soon my webbmaster will create a link to it.

I like to thank Mr Mårdfelt and his crew Sven Yrvind.


To those who diagnose me as being insane, crazy, mad and similar I beg to consider the following.
My planned non-stop circumnavigation in a ten feet boat is a world record attempt.
There are not many branches of sport were a man 73 years old and with a pension of 500 € can successfully compete.
I am not much of a competitor but I have read much about the around in ten challenge and I said to myself “I can do that” “I got a good chance of succeeding.”
Are persons who challenge crazy? Every year many persons try to climb Mount Everest. Smart persons realize that it is much easier, cheaper, and safer to climb a lower mountain.
People also play golf. They try to get a small ball into a distant tiny hole with the help of a club. A smarter person would move closer and use a bigger hole.
I hope these examples illustrate my point and the point is that it has to be difficult, like Kennedy said, we will put a man on the moon, not because it easy but because it is difficult.
Of course a boat twice as long as mine with the same weight will make a better sailer. But my intelligence is good enough to make me realize that if I used a boat twice as long I would have no chance of getting the world record of sailing around the world in the smallest boat.
A boat, a few feet longer, but not more, would definitely be safer, so would driving a custom tank to work be safer than travelling in a small Japanese car but it would be overkill and most people consider a small car sufficiently safe.
A ten feet boat is definitely sufficiently safe to sail south of the capes, not every ten feet boat, but if designed and built and sailed by me. Such a ten feet boat is definitely safer than a 40 feet production boat. Big boats are complicated. They attract big forces. A capsize in one of them is very dangerous.
Small boat sailor Serge Testa sailed across the Indian Ocean in his 12 feet ACROHC AUSTRALIS during the hurricane (cyclone) season. People in Darwin warned him. But he had confidence in his home built boat and set out anyway. Sure enough he encountered 4 hurricanes (cyclones). After 58 days he arrived at Cocos Keeling islands. Trees were broken by the hurricanes and people amazed that he had survived. When asked how he had survived the hurricanes:
Hurricanes? He asked surprised. He had thought that the wind was a bit strong but he had not realized that that he passed through four hurricanes. Big boats would not have survived so easily.
I have spent 50 years with mostly small boats, plus 15 years living on the windward side of a small island in the North Sea. Our house was not many meters from the sea.
During my fifty years with small boats I spent two six months periods cruising the southern high latitudes in boats 19 and 20 feet long, mostly during the winter.
Many of the persons who criticize me haven’t even sailed these waters themselves, some may have, but my guess is that that was in big boats. And big boats are dangerous and uncomfortable and difficult to handle in heavy weather.
Big boats are not only dangerous they waste our planets limited, non renewable resources. Growth is coming to an end. Peak oil has already passed. Limited resources cannot sustain unlimited growth. We better face up to the new coming reality of austerity. By living at sea for one year, non stop, in a ten foot boat I hope to be able to contribute to the necessarily needed new technology which has to emerge if we as civilized humans hope to survive for a few more generations.

Regards Yrvind

January 10, 2012


At sea I had plenty of time to think about my future and my next boat. Mostly she turned out to be a bit longer than the one I was sailing but she was still very narrow. I think that such a boat will make a good cruising boat for the high latitudes sailing I like. But it will cost more, much more.
And my pension? Well, luckily, nowadays I do get about 500 € a month from our government. Unfortunately that is not much to build such a big boat on. But it was tempting because it would give me a place for a bicycle and a girl and I told myself that somehow; if I only tried hard enough, I would manage find the extra money. Inspired, I worked out quite a few details for a boat 5,8 meter long with a 1,5 meter beam.
As an economical back up I also did some drawings of tenfeeters. Why not? I had plenty of time and paper and it was fun.
On December the 3-rd, a week after arriving in Martinique, I was in Paris. Martine, a girl who sailed with me in Anna 1968 met me at Orly.
Luckily she now lived next door to the boat show that opened the same day. There I met many of the minitransat skippers and Eric Henseval, designer of the interesting SOURICEAU 4,75m. He updated me on the small boat scene. Especially interesting I found David Raisons TeamWork Evolution. I managed to get a few words with him.
That a boat with such a full, round bow could win one of the hottest competitions and with such a big margin surprised me greatly.
It did not take me long to realize that if I could make a tenfooter with a similar, round bow that went well to windward I would get much more space in her. Inspired I went back to my note pad.
There are not many sport branches in which a man 73 years old can set a world record. The “around in ten” was one and the challenge tempted me. Besides, if I succeeded, I might as a spin off effect get rich enough to build the bigger cruising boat. The one with enough space for a bike and a girl, but most of all it would keep me healthy and give me fun and it would be a cheaper way out.
Dec 6th in Paris I made the first sketch. The boat became 2,8 meter long with a beam of 1,6 meter. Its salient feature was its tacking mode. It did not tack the usual way like a slalom skier but like a falling leaf. It was a proa, athwartships as well as lengthships symmetrical; stem and stern had the same shape. There was a windward side and a leeside. It had a rudder in each end. I was able to solve the steering problem in a neat way. (– The rudder at the fore end rotated up, out of the water and became a short bowsprit. Downwind it could be angled to windward to let the jib catch more wind. Upwind it could be angled to lee to let the jib get a better, leeward position in relation to the mainsail). Because proas always have the same side to windward the stability problem was easy to solve. Just move heavy things to windward. Interestingly enough after tacking they are still to windward.
But the main reason why I wanted a proa was that, that way I could divide the boat by a lengthwise waterproof bulkhead with a sliding door. I would sleep to windward in a full length bunk and control the sails from a hatch central in the leeward part of the boat on the lee side of the bulkhead.
From reading small boat literature I know that the skippers often get wet, wet by saltwater. I like to watch saltwater waves. I like to swim in it. But like my late mother always told me: “there are few things more disagreeable than getting saltwater and mosquitos inside your bedroom.”
I reasoned that if I sailed in an unbreakable boat and always stayed dry and warm, I would be fine whatever the weather throw at me.
I was happy and proud of my design. That is, until Dec 22. By then gnawing doubts made me realize that all was not well, that it would not only be nice to have a saloon with the same kind of comfortable seat like I had on my latest boat, but even important if I was going successfully to spend one year making an uninterrupted voyage around the world in the tenfeeter.
During my latest sail, changing around was important. I spent a few hours in my bunk reading and designing, then I went back to the saloon and my comfortable easy chair. There I had something to eat or just watched the saltwater waves through the windows. After that I went back to my bed, if I did not take a short walk on deck or a long swim in the saltwater waves. That way I filled my day and life with variety.
So there I was, back to square one, once again.
Basically I do not like beamy boats, 1,5 meter (5 feet) is plenty for me, but I realized I had to do some trade off and swallow the bitter pill if I successfully wanted to sail the wide oceans in a tenfooter and win the world record. Reluctantly I increased the beam to 1,9 meter and the length to 3,0 meter which is just under 10 feet.
My method of construction is sandwich and the hull thickness is about 5 cm (4 cm core plus laminate on each side. This gives excellent strength, insulation and flotation). That increased the maximum inside width to 180 cm. Luckily by concentrating hard I have succeeded in shrinking myself 5 cm, from 172 cm in my youth to present 167 cm.
Now I had created the necessarily conditions that enabled me to draw a athwart bunk 13 cm longer than myself. That bunk would only take 80 cm of the boats 300 cm length.
With that arrangement I could go back to the normal tacking mood. Regrettable I gave up the untried proa concept. Each system has its own advantages and disadvantages. Instead of a longitudinal waterproof bulkhead I draw one athwart the boat. Its door slided up and down. An extra advantage of that arrangement is that when using it as a bunkbord in rough weather I don’t have to close it completely if it is hot. That way I get more ventilation. The main hatch is then of course closed, similar to the system they use in submarines.

I will have two equally high masts and sails of the same shape and area. The boat is schooner rigged. A central hatch will provide ease of handling the sails without going up on deck. The distance to each mast from the edge of the hatch will be a handy 90 cm or 3 feet, the same arrangement that has proved itself so handy on my present boat.
Each mast has two different sails. In strong winds I will use trysails attached to the masts with pockets similar to windsurf sails. Instead of the wishbone I will use a straight horizontal sprit. The masts have no tracks and the sails no slides, one less thing to malfunction on a long voyage. It also makes the masts stronger for the same weight.
In good weather I will use balanced lugsails with an area of 4 to 5 square meters each (44 to 55 square feet). Balanced lugsails are not attached to the mast with neither slides nor goosenecks. Therefore when the wind pipes up all I have to do is to bundle up the lugsail, including its spars and tie it to the deck and hoist the 1,5 square meter (15 sq ft) trysails. They are permanently positioned around the root of the unstayed masts. The downhauls are always attached to each sail, saving work and guaranteeing that I do not loose them a dark, windy night. Out there it is far to the next sail maker.
The unstayed, round, tapered, carbon fiber masts are not longer than 12 feet and not very heavy. They can easily be moved. In the forward part of the boat there are two extra holes to put them in, one on each side of the deckhouse, 80 centimeter distant from each other. For downwind work the masts can be moved to these holes and the sails set goosewinged. The distance between the masts prevents the balanced lugsails from interfering with each other. The full scale sailing model will tell me if it is worth the extra complication.

There will be two rudders on the 1,6 meter wide transom angled outward at 20 degrees. In heavy weather, going down wind, the parallel stay can be shortened wedging the rudders, trailing edge outward. This will act like a brake and decrease the boats speed significantly. As seen under a previous post (A TEN FEET CRUISER IN BIG WAVES) it will also more effectively glue the boat to the wave surface. In a slow moving boat, the acceleration is always at right angel to the wave surface.
The angled rudders will help to prevent broaches as the rudder on the broaching side have a bigger angle of attack and creates more steering power. The other rudder will loose its power.
There will be daggerboards in the rudders to increase their draft when so needed.
The forward lateral area consists of two side by side (not tandem) daggerboards. The advantage is more control, and I am a control freak because only complete control over the boat makes me happy at sea. Also that arrangement moves the center of lateral resistance higher up. Therefore the boat heels less. A tall rig heels the boat more than a short rig. Likewise the equally big force of a deep lateral area heels the boat more than a shallow lateral area.

Enough of that for now, because the most frequently asked question, I guess, is: “Will there be enough displacement for me, all the food, water, books and the hundreds of other thing I will need for a year at sea in a ten feet boat”?
I wish that my readers had kept their ears open during the mathematical lessons in school. A good boat builder keeps his tools sharp, but in my opinion he should also keep his mental tools sharp and mathematics is by far the sharpest mental tool. The following is really a very elementary calculation. But one step outside the normal behavior and a person is a child in a new world and has to forget all he has learnt to get a realistic understanding of the new phenomena he encounters. Going back to the fundamental principals with the help of a little elementary mathematics clear things up.
Let me explain. Frank Andreotti sailed across the Atlantic in the boat Stern. It was 1,72 meter long. The total weight of the boat, food, water, skipper and everything else was 450 kilo. His average speed was 2,5 knots.
Now if I was going to scale up his boat to 3 meter in all dimensions length, beam and depth (do not worry. I am not going to do it. This is just and example of elementary mathematics) I would get 3 divided by 1,72 cubed. That number is 5.3. Multiplying 5.3 by 450 kilo I get 2387 kilo or 5278 pounds of displacement in the new 3-meter boat. This is surely more than enough. It is nearly two and a half tons. Who could have guessed that a wind powered 3-meter boat could carry that much weight?
The speed would increase by the square root of the scale or 1.32 times. This will increase the average speed from 2.5 knots to 3.3 knots.
The new boats stability will increase by the forth power of the scale factor or 9.25 times. That is, if you before could put one person a certain distance from the center without the boat healing to much you can now on the up scaled boat put 9.25 people that same distance from the center. (The number comparing the big boats stability with the smaller one comes from multiplying the new displacement by the new healing arm). This proves that I will have ample margin of stability for the stronger winds I am likely to encounter in the roaring forties.

To keep my heart, lungs and blood vessels fit, I will try to build a hand and foot operated generator.

My first plan was to sail from New Zealand to the Falkland Islands via Cape Horn and make a stop there. During the southern winter 1980 I cruised the islands during four months in a home built 19 footer, so I am familiar with the waters, although I realize that much of the peace are now gone. The war has changed that. Also I have been told there are still some plastic mines left despite thousands of sheep’s walking about trying to clear the ground.

I really do dislike cutting up a passage into many small parts. Also in the back of my mind there is the American proverb: “If a job is worth doing, it is worth doing well”. Clearly the least hassle humans can give me is if I circumnavigate the world non-stop. The more I thought about the idea the more attractive it became. The more I analyzed the project by going back to the fundamental principals the more feasible it seemed.

This is the big picture, but of course, the devil is in the details and they will take time and ingenuity not only to work out, but also, equally important and more difficult, make sure that they do not interfere with each other.
So with many good ideas and one “idée fixe” I have decided to go ahead.
However, do not hold your breath I do not have much money and my speed of work has dropped as my years has advanced, nor do I have a young female adept helping me as I often had in my younger days when I was more beautiful. Also nowadays I am more careful and there are still many problems to solve and calculations to do.

The good thing is as the old jungle proverb says, “The young lions has sharp claws, but the old baboons knows where the fleas hide”
To be continued…

Regards Yrvind

January 8, 2012

Yrvind Ten

This film clip shows the first model of Yrvinds new boat project, Yrvind Ten. The final boat will be ten feet long and designed for a circumnavigation south of the southernmost five Caps.

January 5, 2012



The following discourse might for some be a bit abstract. It has so to be because circumnavigating the world nonstop in a ten feet boat is not as yet an every day occurrence. Such an activity has previously only been done in big boats. To change size is like stepping into another dimension. One has to forget what one has learned and start all over, going back to the fundamental principals.

Having 50 years experience with small boats helps me, but even so, this new project makes me a child in a new world.

Froude numbers are used to determine the resistance and speed of a partially submerged object moving through water. They permit the comparison of objects of different sizes. They are calculated by dividing the speed by the square root of the product of gravity and the objects waterline length.

Froude numbers works well for towing tanks were there are no waves and at sea when the object is a ship; big enough not to be influenced by waves. It is regrettable that they are not applicable for accelerated systems like a ten-foot cruiser in big ocean waves. The real heavy weather situation is to complex for Froude numbers. They do not give a true picture comparing a small boats resistance and speed with other objects.

To surmount that shortcoming I have created a wave theory of my own. My trick was to use acceleration instead of gravity in the above formula. That makes my new theory universally applicable.

Unfortunately because the acceleration of a small boat at sea changes constantly by its speed and the wave amplitude, a function instead of the gravity constant, must be used to describe how resistance and speed changes over time.

Regrettably I do not have neither the knowledge nor the resources to give a continues description of what is happening.

Still the two extreme values are easily calculated. The result is very interesting and all the other values fall between them. Much is therefore illuminated.

It is a well-known fact that particles in the surface water describe a vertical, circular movement. From this follows that objects floating in this environment are subject to a centrifugal force – modified of course by the objects foreword movement.

The gravity and the centrifugal accelerations combine to create a new force that is always at right angle to the waters surface.

Thus unlike a skier, a slow ten feet cruiser cannot slide down a wave surface, also the same boat does not need energy to climb the water surface from the trough to the crest. This is of course a paradox. It seems that potential energy is created out of thin air. It is not so. The lifting force comes from the centrifugal force. Heavy logs floats with ease up against gravity from the trough to the crest of a wave.

At the top of the wave the centrifugal acceleration and gravity works against each other. At the bottom of the wave they combine.

Accelerations with values of 4,9 m/ sec squared at the top of the wave and 14,7 m/sec squared at its bottom are not extreme. The corresponding Froude numbers for a boat with 9 feet waterline length are 0,27 at the crest and 0,16 at trough. Thus, in the trough, in a following wind, there is, luckily, a striking speed increase through the water, just where it is most needed.

Another important consequence of being small in big waves is that a ten feet cruiser moving slowly through the surface water will at the crest become very light due to the centrifugal acceleration. In the above case its weight at the trough is three times as heavy as at the crest. Consequently its stability is also three times as big in the trough. And this case is not extreme as can easily be calculated.

The boat being so light at the crest may then get enough power from its sail to be lifted it out of the Archimedes cavity it is trapped in. Of course inertia still works, as it always does, even in gravity free space.

At the crest the surface water is mowing in the direction of the wind at a speed of several knots.

(Because the boat is so light at the crest, it there loses much of its stability. The consequently sudden heeling lead the ignorant person to believe that it is more wind at the top of the wave. The right answer is. The boat heels over because the acceleration is less at the crest than at the trough. But the boat still floats at the same waterline because the weight of the water at the crest is also less then in the trough.)

At the trough the boat meets surface water that is mowing against the wind at the speed of several knots. The boats speed through the water therefore increases even though its speed over the ground is the same. As we have seen, luckily the boat is now moving at very low “Froude numbers” this decreases its resistance for a given speed.

Think about it in this way, sailing at the crest is a bit like sailing on the moon. There gravity is low. Everything happens slowly. Consequently sailing on the moon will be slower than on earth.

On the other hand, sailing in the trough is like sailing on Jupiter. There gravity is strong. Everything happens fast. Consequently sailing on Jupiter will be faster than on earth.

During my planned circumnavigation I calculate with an average speed of 2 knots. This will give me a very low Froude number. Thus about 75% of my boats resistance will come from friction. Wave resistance is of lesser importance. Therefore the bow can be made very blunt. This gives my boat more displacement and enables me to have a very high prismatic coefficient .65 to .7. A side effect of this is that it gives my small cruiser very good stability for a given beam.

Clearly it is paradoxical that a 10 feet boat can circumnavigate on a small Froude number, but the hull speed of a boat is in proportion to the square root of its waterline. Now there is something funny about the graph of that function. It is of course the mirror image of the square graph, the common parabola as reflected in the bisector of the x-y axes. Now the parabola when its x-values are small keeps very close to x-axis and then as it gains momentum quickly rises to the sky and becomes nearly vertical. The square root graph does the opposite, at small values for x (in this example a 10 feet cruising boat with a short waterline) it follows the y-axis rising quickly towards the sky, but as x gets bigger, as for big boats, it flattens out and becomes almost horizontal. Consequently a few more feet waterline on big boats does not increase their speed significantly. This mathematical relationship favours the small boat and explains why I can circumnavigate on small Froude number.

These are just some reflections on one aspect of small boat sailing to show that the behavior of a small boat is not evident. That landlubbers and ignorant big boat sailors better not condemn my endeavor before they have educated themselves.

Regards Yrvind

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