The best place for ventilation system that will keep Exlex Minor dry inside even when upside down is on the main bulkhead. Like always on a small ocean going yacht things interfere, like the waterproof hatch, the storage etc as well as the incoming air and the outgoing air that has to cross each other. Also the opening for incoming the air and outgoing air be as far apart as possible so that the incoming air does not get sucked out before getting into the boat.

To help me sort out my thoughts I used the mockup in 3 dimensions and two ropes one twisted one braided. By giving them a few extra bends I figured out how to install the ducts. – Each bend reduces the airflow so I had to make as few as possible. Where I made a bend I increased the channel diameter to compensate.

To new readers the system works on the principle that water enter the ventilation channel cannot rise above the sea level. Hence the ducts start by crossing the boat athwartships then descending to as far as possible.  That way whatever angle of heel, even upside down some part of the ducts of both the incoming air and the outgoing air is always above the waterline, thus blocking water from entering the boat. See earlier posts and illustrations.

Below a picture showing how the ducts are bendt.

Below showing in detail the extra bends of the brided rope.

Below a picture of the main bulkhead. The thin lines indicating where the door to the sleeping room is, is probably to thin to been seen.

The below illustration is by Pierre Herve showing the slightly different ventilation on Exlex. Thanks Pierre.

To bee continued…

Regards Yrvind



I have now illustrated the modell with sails. There are 5 masts. A change have been made to the foremost mast. Its now a Ljungström rig that furls dobble sails on a rotating mast. Rigging the modell I realised the was more advantageus. It enabelded the fore hatch to slide foreward when openend because the mast is further forward. It like the other masts are selfsupporting, getting more space around the hatch. It was also more simpel doing away with the jib furling mekanism right at the bow.

Now one of the aft mast will be made of glass fiber to house the VHF-antenna.

The picture below shows Exlex Minor with all sails up on a broad reach.


The picture beow shows Exlex Minor running before a strong wind. The big masts and sails are stowed on deck and the aft sails are reefed. The twin Ljunström sails are out one on each side, wing and wing  about 120°, controlling them with short whisker poles. Work on the foresails is safely done from the forehatch. The main cabin is closed with a waterproof door.

I am ready to start building. I only need plywood to get started with the full scale sailing modell.

To bee continued…

Regards Yrvind


Today the modell is nearly complete and I am very pleased with her shape so I did a mockup of her midsection to verify if it suited me anatomically. Beppe my webmaster was here and took the pictures.

The modell with 4 of the 5 masts. The fift one will be towards the bow not unstayed but supported by shrouds and a stay with a small roller furling device. The notebook in which I did all the drawings during my Atlantic sail in Exlex is in the background. Klick once or twice to enlarge.

Above, me and the almost twodimensional mockup. I feel very right. compared to Exlex here is tons of space. I sit athwartships.

To be continued…

Regards Yrvind.


Do it again, do it right.

I was not satisfied with the shape of the bow therefore I made an other one with a more rounded bow.

Modern yachts in contrast have very sharp wave piercing bows. Good for windward work but not so good for downwind. For several hundred years the hull shape was “cods head, mackeril tail”. Those ships sailed similar routes that cruising people chose. I belive in “cods head, mackeril tail” when running with a gale behind you. My belive is that that kind of bow reduces the risk of broaching.

Broaching is not a big deal for a small boat but its a nice feeling to sail a boat that behaves well in wild weather.

Below are some pictures.

First out me and the two models

On the secound modell I have started to build up the starboard sidedeck.

To be continued…

Regards Yrvind


Below are some pictures confirming correct displacement.

The planned weight of Exlex Minor is ready for 5-6000 nautical miles is 800 kilos. The 1/10 modell weighs 0.8 kilo. Dipping her in the workshop baisen conforms that the draft 20 mm corresponding to 20 cm on the full scale boat is correct, correct .

To make it easier to see the waterline I have added some sawdust to the water. Click once or twice to enlarge.

Sawdust is a good thing for many uses.

To be continued…

Regards Yrvind


Thursday night late I was back home in Västervik determined to get sailing in a new boat, Exlex Minor, 5.8 X 1.12 meters as soon as possible. Hence after sorting out several bourgeoi duties like mail, bank, internet I was back in workshop designing.

During my 40 days at sea I had well prepared my mind.

Nowadays yacht designing is almost exclusively done by computer and that is an excellent way of doing it. In the 70- I designed by ducks and splines. Later I got help from clever people with computers ,like John Letcher, Rolf Eliasson, Matt Layden and Guy Liljegren. At sea I thought of an other way.

Given a boats lenght, beam and draft there is a very simple way of figure out displacement using the prismatic coefficient. Prismatic coefficient is the fullness of the hull. 0.54 is common for sailboats. Sailboats also usally are 3 beams long, Exlex Minor hovewer are more than 5 beams long. Boats with a good lenght ratio can have higher prismatics. A higher prismatics gives more stability and a higher top speed for a given waterline lenght. I chose 0,7.

By multiply the midsection area by the lenght of the waterline by the prismatic the displacement is fond. In the case of Exlex Minor it is very simple just multiply beam by draft as its an rectangle

Exlex will have a waterline of about 5.6 meters she will have a beam of 1.12 meters. At 18 cm draft she gets 790 kilos displacement. At 20 cm draft ( about 8 inches) she gets 878 kilos displacement.

I started with a block of wood 58 cm long 5.6 cm vide and 9 cm high the bottom part was of MDF board to indicate the underwater part. The tricky part was to get the prismatics right, but as I have been around boats for a long time I got a sense of their shape. As they are usually 3 beams long I imagined a boat 3.36 meter long cut it in middle and added enough midpart to make it 5.8 meter long. Cargo ships are designed along similar lines, a forword part, an aft part and a parrallel middle section.

After shaping a half modell I made offsets of the surfaces and made a model.

Below are some pictures.

The wooden block being glued.

Clamping 3.7 mm plywood to the half modell to take off the lines.

The modell

The modell on a chair. More work will be done to her like giving her a spoon bow and make her waterproof. That done I will load her to 0.8 kilos, she is an 1/10 scale modell and float her to find her waterline.

I thank everyone who has donated money to help me with my project and get me back from Madeira. My economy has now crashed and I need to get plywood and other items for an full scale sailing modell before starting on the sandwich composite boat. I hope you will continue to support me. Me I will let everyone for free use my ideas and drawings as published here to build small safe enviromentally friendly boats. I really think I am into something new a good, a mountain bike for the oceans.

To be continued…

Regards Yrvind.

Back home

I am back home. There is many things to sort out, for example to get a new internet connection.

As soon I am settled I will start working this site and build a new and better boat called Exlex Minor with a length of 5.8 meters, beam 1,12 meters, draft of hull 0,18 meters and displacements loaded for 60 days at sea, 800 kilos. That will give approximately 5000 nautical miles. The building of this boat will be presented on this blogg.

I take the opportunity to thank everyone who has contributed to my last project, because at sea I been unable to express my gratitude.

Regards Yrvind