Maintaining and preserving a wooden boat is simple. Raw linseed oil and turpentine oil are generally used for impregnation. Use a lot, use it often. It is here the case to ensure that one surface, preferably the inner surface, of the planking is open, i.e. it has not been treated with anything that forms a sealed surface.

The protection for the wood can be reinforced by mixing in a greater or lesser fraction of pine tar into this oil, particularly for the latter coats. Other types of additive in the form of fungicides normally have a limited effect, and generally have a negative effect on the linseed oil through undesired reactions that change the chemical composition.

Continuing the idea of simple treatment, we can achieve a water-repellent surface treatment of the outer surface of the planking, for example, using varnish. Varnish is originally boiled linseed oil, which forms a polished and impermeable surface after repeated coats are applied. At least 10 coats are normally required, maybe more than 20, in order to achieve a saturated surface on which the linseed oil can dry to form a hard and rigid surface. Varnish has developed from this simple beginning over hundreds of years. The aim has been to be able to reduce the number of coats, shorten the drying time, increase the polish, etc. Additives in the form of tung oil, stand oil, have been used, and more recently alkydes and solvents have become available.

The ocean is one of the toughest surroundings that wood can be exposed to. Change of humidity, change of temperature, salt, sun, ship’s worm, forces of motion. The ocean places very heavy demands on the material that can be used.

Seals of joints between, for example, planking or the deck, drying cracks, penetrations and other holes in the hull and superstructure – it must be possible to seal all of these with something that holds even under the most terrible conditions, something that can withstand the motion that a vessel is subject to. The seals may not be too hard, either, such that it is possible to press them out of the joint or crack if this is required.