Visit to Kemppi to find the solutions and tools for welding the hull of aluminium sailboat

Few weeks ago I had a privilege to visit the headquarters and a factory of our local welding machine brand Kemppi. We had an interesting conversation related to Li Yachts project and of course about welding of aluminium. My visit was also the first milestone on the way of preparations towards construction of prototype boats. We have used Kemppi’s products in underwater welding dive operations and in refit work of our old aluminium yacht. So it was a logical move to contact Kemppi also within this ongoing project.

Founder of the company Martti Kemppi was an electrician and wanted to design a welding machine, which has great welding characteristics but it must be easy to use representing minimalistic design. A joy to weld with. We have the same approach to boat design – as a pioneer aviator Antoine de Saint-Exupéry has written in 1939 ”Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away.” 

Kemppi is a Finnish family owned company, which still bears the surname of the founder and the company is still owned by the same family. Kemppi is founded in 1949 during tough times after the war. First products were carts for hauling concrete and milk. To produce these products the welding was needed and soon the clever electrician was building his own welding equipments.

During hectic post-war reconstruction of the country there was a demand of welding machines, which gave the young company the opportunity to grow. The production expanded and as early as 1950s Kemppi started to import welding machines to neighboring countries. Kemppi’s two main manufacturing plants are located in Finland, in addition to which it has one production plant for local Asian products in India. Kemppi has over 600 employees.

Now Kemppi is a globally operating company, which has retained the values of family owned business. The people that I met during my visit were easy to approach and they had time to listen my a story of my little project called Li Yachts and I received encouraging feedback.

Their welding engineer introduced me the new X8 MIG Welder. We were able to go straight to the details about methods how to reach for hight quality welds combined with effective productivity of the welding process. To me that represents the ability to understand demands and challenges of the customer.

With strong forward carrying guts in my mind I already imagined our first hull with the X8 beside her. My head was filled with thoughts how to rig the device to allow easy operation in different building steps of the hull. I also imagined the huge leap of welding technology compared to the machines that the builders of original Li have used fifty years ago.

The new generation of MIG welder allows even small scale manufacturers to exploit the benefits of the new aiding solutions for welding based on industrial Internet of things (IIoT). That’s possible when X8 is combined with Kemppi’s welding management software WeldEye. That ensures the use of optimal welding parameters and a quality control for the every seam. Errors in welding process caused by incorrect parameters are minimized. As-built weld traceability data can be stored as an annex of hull classification.

The wireless control pad of X8 allows the welder the full control of the machine and ability to view digital welding procedure specification (WPS) instructions via WeldEye on the worksite when ever needed. He or she is able to improve personal work process by saving fine tuned settings for further use to match up for the personal touch of welding. As we know, the aluminium boat is as strong as its weakest seam.

Here you can see new X8 in use in the factory of Buster Boats in Finland. Kemppi has also invited the boat manufacturer to take a part to design and development stages of X8 and welders were able to give user feedback of the product.

From sustainable development’s point of view Kemppi’s welding machines have high energy efficient inverter technology. Their products are designed with long service life in mind, but also recycling in the end of product’s life-cycle is taken into account when selecting materials. Machines are repairable and some of them even physically updatable. For example the power source of X8 is upgradeable.



Six months evolution of new sailboat concept design in pictures

When the year is coming to an end it’s time to look back to see what has happened and plan near future with full speed ahead.

We started in June based on my hand drawn notebooks and here we are now. Next step will be CFD-analysis of the hull and after minor improvements the cutting files for CNC will be produced. And then we are ready for proto series!

Images below describes best the progress of the design project.

At first the most fresh images – end of the year has gone well!

Explorer zentralschwert segelboot

Expedition centreboard sailboat

Frames and stringers added to the design

Design drawing yacht design

Li Yachts sailboat design process

Zero fossil fuels sailboat concept for ocean voyaging

3d-sketch of the hull after one more week of work

Drawing from notebook

Li Yachts 47 sketch

Sketch drawing of ocean expedition sailboat in notebook

Power of the blue moment

Days are getting shorter but in the design project we need to push forward and maintain the energy for the work.

There are many things in the design process that needs to be realized from sketches to real design. We also need to produce first rendered images of the boat to give people better idea of the concept.

Few fundamental arrangements will require lots of thinking. Just to mention one, cockpit is one of these. My basic idea was of course based of simplicity and safety – narrow sole with a tiller steering. In offshore there is nobody behind the wheel and in harsh conditions I prefer better support and safety of narrow cockpit. That also gives more space below and large volume lazarette under aft deck that would be lost with an open transom, which is needed with large cockpit with the wheel. For some people the wheel is a must, but obviously that won’t work with the same cockpit design with my original idea.

Sometimes it feels that there is too many things to consider and choices to make. Some might say that the solution would be just to design two options. Reality is that in the boat everything is connected to each others and that’s why changing one arrangement causes domino effect of changes – so designing two optional choices is not always the answer.

Basic principle that rises up every day is to keep in mind the right guideline answers to question “why”.

There are also thoughts that needs to be kept in background of mind in a project like this. If you let yourself to think too much about risks or for example challenges of proto boats you will lose visibility of the progress and waste the courage to go on.

After a walk and taking a few shots of beautiful blue moment of November’s fading day I was more focused again. The goal of opportunity to live onboard surrounded by these experiences of nature every day is pushing me forward!

Blue moment in shore of the Baltic Sea

Blue moment of short November's day at waters edge of Baltic Sea

Benefits of centreboard sailboat, dériveur intégral – as they say in France, evolution of my thoughts

Here is the shortened description of evolution of my thoughts when determining the hull type of the boat that we are designing – centreboard sailboat, dériveur intégral. All begins of course with defining requirements, because there is not a perfect solution that is suitable for all! So there is not absolutely right or wrong solutions.

With a fin keeled yacht I was rather satisfied with the performance. Even though the boat was only 22 ft, I wasn’t happy with the draft of the hull and vulnerability of the keel and rudder. That prevented many sheltered anchorages and interesting routes. Also the propeller had no protection. On hard during wintertime, the boat was difficult to transport and support.

The obvious solution was a long keeler metal boat. Now the draft was less with solid keel and rudder. But the performance is, how I can say it with diplomatic words to our boat, let me say classical.

The next evolution of my thoughts was a boat with longish fin keel. But a low aspect ratio fin keel is not so effective related of generating lift. Then I considered lifting or pivoting ballasted keel, but the forces that the construction is faced of are high and there is a risk of real troubles.

Then I started to study centreboard yachts that are known in France with name dériveur intégral. As many of us, I have been suspicious about their stability, but then I began to understand what was it all about. AVS (angle of vanishing stability) is probably still the best known and easy to understand value to describe the stability of the vessel. It is simply the tilt angle where the vessel loses its stability when RM (righting moment) falls to zero. Beyond that angle RM becomes negative and causes the vessel to turn upside down. Of course internally ballasted centreboarder has lower AVS and their ability to carry sails when struggling close hauled in hard blow is limited. The boat has higher centre of gravity, which has also a positive effect that makes her easier for the crew, because you are closer of the roll axis of the hull, not in the long arm of pendulum. And combined with above moderate form stability of chined hull, the boat is also more restful to live at anchor. But you can’t have all strengths in a same package!

When I asked our designer Jean-François about the centre of the gravity at a beginning of the design process he explained in the words of one syllable that centreboarder that is made of aluminium has lower centre of gravity than steel boat with full keel.

AVS describes only a static stability situation, but I believe that in real life the dynamic stability of the boat is more important related to the safety in extreme conditions, because the forces involved are never static. The thinking is based on the law of the force and counterforce. When hit by a breaker abeam the underwater body of the hull and its appendices generates counterforce for thrust of the wave in the form of lateral grip. Under the force of the wave the boat with enough lateral resistance sideways starts to tilt. And if the situation gets worse then the boat might invert in the procedure which is described as “tripping over the keel”. Eric Tabarly illustrated the effect in his book “Guide pratique de manoeuvre” (Practical yacht handling).  The boat with long keel has a huge lateral resistance but some designs with short keel might also have enough surface area to produce enough lateral resistance for tripping.

Centreboard boat with centreboard hoisted has less counterforce by lateral resistance of the underwater body and it gives the boat the ability to absorb the power of breaker to sideslip movement maintaining its upright position. And because centre of lateral resistance is well aft the boat turns its bow away of wave crest.

If ever getting inverted despite of what is described above the design of the deck and superstructure has an important meaning of reducing inverted stability. The long and rather narrow cabin trunk and the extended pilothouse with watertight door will make the boat less stable if inverted. Please see the picture below, our boat has a relatively high conical shaped superstructure cross section for a reason. Low volume enclosed cockpit also adds buoyancy aft and helps the boat float higher in an inverted position. These things have an important role in internally ballasted boat that have a lower centre of gravity in inverted position compared to a fin keeler. When the next wave tilts the inverted boat, the centre of buoyancy moves quickly outwards of the centerline and helps highly floating boat to turn back upright again.

Zentralschwert segelboot

Of course the boat with a ballasted lifting keel will have greater righting moment, but there are also cons related to the safety. We need to keep in mind that if you lose the ballasted lifting keel you also lose the stability of the boat.

You can’t raise the lifting ballast keel to minimize lateral resistance in extreme survival situations requiring high dynamic stability. Also if you want to anchor or navigate in very shallow waters with the ballasted lifting keel in up position the boat can be more rolly because her centre of gravity has risen, how much is depending whether the ballast is placed in a bulb or cast into a whole keel without the bulb.

The operating systems of ballasted lifting or swing keels are complex compared to simple rope and winch system by which we can manage with a non ballasted centreboard. Also the forces to the operating system and to the hull are higher with lifting ballast keels.

With the lifting ballast keel there is no option to balance the boat by changing the centre of lateral resistance as can be done by pivoting the non ballasted centreboard.

For me balancing the boat under sail has always been one of the greatest satisfactions when sailing. I have always wondered why balancing of the boat is usually done with sails only. Centreboard yacht will have much more ability in terms of adjusting balance in different conditions by moving the centre of lateral resistance by pivoting the centreboard. If stern daggerboards are added the weather helm can be reduced even more effectively when close hauled. In running or broad reach conditions the centreboard is hoisted and the centre of the lateral resistance moves aft making the boat very course stabile. The boat flies straight like an arrow, and that is the most valuable feature if you want to sail far destinations surrounded by blue water.

When dealing with the ice the underwater hull with canoe body only when centreboard retracted is a plus. If needed the boat can be pulled up like a sledge.

Shallow draft allows many anchorages which aren’t possible to most of the boats to explore or seek shelter. Centreboard sailboat can also dry out safely when needed.