A job, which is finding ever more consensus and also exceptionally strengthens the hull, is re-covering with thin plates of solid wood or plywood, both sides and bottom, making a “cross” with the new covering. This intervention (re-planking) can be carried out on boats with rounded as well as angular hulls and it is mainly targeted at longitudinal or cross planking boats in order to give to the boat structure more reliability and to guarantee reduced maintenance. Recently a renowned magazine in the sector presented a report about an extra planking installed on a motor boat above 20 metres, with more than 30 working years, which during this important maintenance also had the engines changed for new ones with higher performances. These interventions are aimed not only to update the construction techniques which were already of high level but also to apply C-Systems’ 10 10 CFS epoxy resin where before everything was in the hands of nails and screws.
Recently we have encountered boats “restructured” more than ten years ago; they looked as if they had been constructed yesterday. Before starting it is important that the hull is well supported on a suitable mount, holding its shape, without incorrect sagging or twisting, and that it undergoes a good drying out, after removing old paint.
Caulking with cotton or thin wooden strips will be carried out according to the precautions described above. All surfaces will also be smoothed evenly so that the planking is perfectly levelled.
A new lamination (re-planking) can be carried out using solid wood as well as plywood. Plywood, or solid wood, goes from 3 mm thickness for boats from 4 to 6 metres, to 5 mm thickness for boats up to 10 m and so on (3 mm every 4 – 6 metres). Plywood is easy to be used and installed because a small saw is enough to obtain strips in the right measure. Furthermore the various internal layers give, in comparison to heartwood, a higher dimensional stability.
You start from the boat centre with inclined strips from 35 to 45° so that the external vein is going to form the best X cross with the planking vein underneath optimising also its bending facility. The strip is fixed with the stapler and another 4 to 5 strips are prepared, numbered and shaped slightly so that their edges are adherent, marking reference points. Then you start the installation by well impregnating the hull and the strips with C-Systems’ 10 10 CFS. Afterwards a certain quantity of C-Systems’ 10 10 CFS with Microfiller Powder is prepared and applied on the hull with a toothed spatula. Then the strip is laid up and stapled to keep it perfectly in position, then you go on with the other strips. Possible small spaces between the plates are filled with Microfiller Powder. It is also possible to change the strips “weaving” next to the poop and bow or wherever necessary. It is important that the vein of the new support, which we are placing, is always going to form an X with the boat wood vein.
Once the cover is finished we remove all clips, than everything is sanded with paper 40 – 60. The new planking is protected with a complete C-Systems’ 10 10 CFS treatment. On the keel it is advisable to make a fillet with Microfiller Powder with a proper joint.
Another usage practiced for a long time, is the construction technique for new craft covering the entire hull with C-Systems’ 10 10 CFS and glass cloth (mainly for the longitudinal solid wood construction), a certain part or the board joining points, of the corners (mainly for plywood boats) and all parts with higher wear, like stem posts, transom frame, stern boards, keels, etc. It is important to note that the glass cloth and epoxy resin cover has to respect the same fundamental laws:
1st wood has to be perfectly dry (that is to say with the foreseen moisture content) as required by Naval Registers.
2nd the parts to be covered in glass cloth have to be mechanically sound, well assembled, properly dimensioned and without hard edges, because the cloth would loose part of its strength at those that points.
When applying the cloth on outer edges it is necessary to round these with a diameter of at least 2 cm. When the cloth is applied to an inside radius with C-Systems’ 10 10 CFS and Microfiller Powder then to at least a 5 cm diameter. Contact with a larger diameter will give the highest resistance to the applied cloth. Ensure that this cloth is “dressed” for epoxy resin otherwise the bond will not be so good. Usually the cloth used is bi-directional and in order to obtain better results it should be “lattice mounted” – obliquely, that is to say in order to form an X with the wood grain direction.
Using instead a bi-axial cloth ± 45° solves this problem and has a resistance and a “strength” superior to a bi-directional cloth with the same weight and glass quality because it always “crosses” timbers in the right way, but also due to the way its weave pattern. This cloth is also interesting when boat building with, lets say 15 mm planks are foreseen, we use 8 – 9 mm and add a glass reinforcement to ensure the 15 mm resistance, with the advantage of having 30% less in total weight. For all works where glass cloth is foreseen, or chosen, cleaning the parts, the drying, the impregnation and filling with C-Systems’ 10 10 CFS and its additives is determining.
The following glass cloth application with C-Systems’ 10 10 CFS must give consistency, reliability and beauty to the boat. It never has to be a work which can be classified as plastification.
On some regatta boats, built over 30 years ago, these solutions were chosen for their lightness, stoutness and…… long-term reliability. If you see them during your trips or at a regatta you will be able to admire them because they still look new and still have a bright future.
The use and application of this glass cloth is documented in our VHS video tapes. Also available is a CD with photographs about work on solid wood boats. Sent free of charge when placing the order for the VHS video tapes.