The gussets where cut according to the templates I took from the plans. With the cardboard templates I drew a pattern on the 10mm Okoumé plywood sheet to have as little waste as possible. Thanks to the thin Festool plunge saw blade of 1.8 mm precise cuts are achievable. I left small connectors in the plywood which I have to cut out later with the Japanese saw.
The Douglas fir boards where cut to size. With the Festool plunge saw I cut the boards lengthwise with oversize in width so that they can be planed to the right size. The rods of 60mm where then planed with the Metabo thicknesser to 22mm height and 55mm width to build the frames. A few special sizes for the mast support, bowsprit etc. still had to be made. It was a heavy job and took me one noisy day in dust.
Let’s continue with the documentation on building the frames. First of all you need a good, leveled workbench in a well tempered room to build the frames. I organised all of my tools in a tiny 3.5 x 5 m basement room. Ideal to adapt to the small boat feeling and good training for the coming cruises. I set up a 230×150 cm MFT perforated table. I bought a lot of clamps and built some helpers myself to press the wooden frames on the perforated board when glueing. The dry and warm conditions are ideal for glueing epoxy. This workshop also allows me to build the rudder, dagger boards, skeg and other small parts before moving to a larger shed to assemble the boat. Super productiv working at home day and nightime, With reggae music and some cold beers I can get into the mood for the Caribbean. Hey life is good!
Christian CG #103 and I arranged a weekend to cast the keel bulbs. Friday after work we met at Christian’s workshop to do the preparation. Christian ordered 320kg of scrap lead from a local wrecker / recycler. We sorted the lead and prepared it in 80kg portions to be sure that the pieces fit in the melting pot. To get clean pieces of lead we had to remove some dirt (silicone and roofing felt). Attention at this point! We discovered some parts that are not lead. Other metal parts and cartridge case from projectiles have been mixed in underneath. We had to sort it out carefully. The following saturday morning we started with setting up the casting station.
We were curious and a bit nervous how we would succeed in melting the lead. With an 8kw gas stove underneath and a gas flame from the top of the melting pot we were able to melt the 75kg in 15 minutes. When lead was melted we had to remove from the surface between 2 and 3 kg lead slag.
Before casting we heated up the cemented bulb mould with the gasflame. Then we pourred the lead into the mould.
After 4 hours of cooling we lifted the mould and turned it upside down to get the bulbs out.
In total we pourred 4 bulbs for our boats CG #103 and CG #66. This was a real succesful and funny day in building our ClassGlobe boats.
Christian CG #103 took care of the construction of the mould. We ordered from a model builder a 3D printed positive form of the keel bulb in styrofoam. Christian has doubled it up by 3cm to create enough space for the shrinkage during the casting process. The styrofoam model was covered with 2 layers of epoxy to get a smooth surface. Christian built a box with the external dimensions H 24 cm, W 40 cm, L 105 cm. He cemented the bulb model with steel reinforcements. Small bubbles and bumps in the cement surface cannot be avoided. Thus the negative mould was smoothed with a thin plaster layer and sanding. The cemented form has to dry in the shed for a few weeks so that it loses moisture. Christian built 2 moulds because we had no experience whether the mould break and in addition to speed up the casting process.
Many thanks Christian CG #103! Awesome job!
I’ve been thinking a long time what is the best way for casting the bulb. The best option seems to me melting the lead in a gas cylinder. Luckily I found an old gas cylinder in my father’s shed. But what is the safest way to cast the 75 kg of hot liquid lead without putting yourself in danger. So my father (an engineer) and I made some thoughts. It makes you very creative when there is enough stuff lying around in your shed. The result was a very stable construction with scaffold tubes. It is transportable and detachable to a minimum size to be stowed away in the workshop or transporation in the car. We where able to do small adjustments to put it in the perfect position to the mould and set it up for the casting job. It was created from leftovers that have been lying around for years. This is how sustainable boat building works.
After we had planned the framework we set about preparing the melting pot. First i cut the top of the gas cylinder with an angle grinder. It is important that it is completely empty (danger of explosion). Propane and butane is heavier than air and so there is still some gas left in the tank even if you opened the valve properly. It is best to unscrew the valve and fill it up with water so that all the remaining gas escapes. Then we measured the level of liquid lead in the cylinder. This is important to determine the center of rotation when pouring the lead into the mould. 75kg lead has a volume of approx. 7 liters with a specific weight of 11 kg lead per liter. We filled 7 liters of water into the cylinder, measured the water level and marked this level on the outside. Above the middle of the water level we positioned the center of rotation. We made the fixing points for the axle and the liftingbar from bigger metal tubes and the handles that we cut off before. After a busy day I was happy with the construction which gave me headaches for a long time. I could hardly wait the big day of pouring the lead.
Yes plywood is here 🙂
The organization of the plywood turned into the first adventure. For boat building you need certified marine plywood of very good quality. Fortunately, you can buy this very close by. This excellent plywood which was used also by building the ClassGlobe #01 i ordered in Italy. But the purchase was the first obstacle of hundreds that will come.
To explain for the overseas readers. It’s only 250 km but there are worlds in between european countries. Not that crossing the Alps is a big hurdle these days to get some plywood. No! It is the mentality and peculiarity of certain national borders that are the biggest problem in Europe. And the corona situation is the icing on the cake. The service of the company nord compensati was very professional and very nice. After waiting some hours and aid money for customs clearence the mircale happens. I was finally able to cross the Italian border. The import documents for Switzerland were done in a few minutes with digital help from the customs app. So I recommend everyone to avoid the time consuming and bullying customs in Italy and have it delivered by professionals. Despite everything, I was happy to finally have my plywood at home in the workshop that evening.
I planned to start building with simple tools that I already found in my workshop. Soon I realized that it wasn’t really fun when I was annoyed about the poor quality. In my profession I always follow the dogma of my professor: Material and tools must never fail. Keeping an eye on my health made me buy quality tools … a little more expensive but worth the money.
For boatbuilding a powerful sander and efficient suction system is a must have. I trust in the products from companies Mirka and Festool.
Since i have to clean up the workspace / car parking lot every time i finished a working day and for better health protection i decided not saving money on a good suction system. The very expensive Festool CTL 26 model with cyclone filter on top is in every day use and i never regret the purchase. In combination with the Festool suction system the Mirka ecentric sander does a very efficient clean job.
To plane the oregon pine timber to the necessary dimensions a stationary planer is very useful. I really enjoy this Metabo DH 330 planer who is doing a great job. Instead of a chop saw i use a hand held custom made mitre saw to cut the timber. Equipped with a Japanese saw blade, I get precise cuts in a second. Less noise and more manual work…. i love it.
For the remaining standard woodworking i count on a basic set of tools in my workshop for example small work bench, drilling machine, cordless screwdriver, jigsaw, circular saw, band saw, router, Japanese saw dozuki / ryoba, chisels….
I chose Oregon Pine (Douglas fir) for the basic structure. It is traditionally used in boat construction for centuries. This wood is hard and straight grained and has good rot resistance. It is easy to work with, machined well, strong for it’s weight, bends well.
The availability in the shops is usually good in spring when many people starting their outdoor construction projects in the garden.
However the quality you can buy is often poor. Most of it is „plantation wood“ and grown too quickly / soft under these conditions. You have to make a good selection and carefully sort out each piece. The better quality is fine-grained max. 20 rings to the inch (25mm) and without knotholes.
Better to choose fine grain oregon pine max. 20 rings to the inch (25mm). Pieces below with coarse grain.
In cross section make sure to choose pieces with straight grain (parallel and 90° angle to the surface) from bigger trees. Avoid the wood from small trees because the pieces have mostly curved rings (inner rings from the tree) which gives possible twisting.
Straight grain in cross section gives less distortion problems (top piece of wood above in the picture). The pieces below are from smaller trees. You can see the curved rings from the tree core.
Step 1 (January – March 2023)
Step 2Â (April – Oktober 2023)
Step 3Â (February – Mai 2024)
Mai 2024 launching ceremony and go sailing 🙂