DNV GL MATERIALS AND WELDING II-2-2 PDF

General

Classification according to the field of application

Only proven boatbuilding wood shall be used for all timber components exposed to water and weather, i. e. timber with good resistance to water and weather, fungal attack and insect infestation, as well as with good mechanical properties that are also suitable for the particular application. Furthermore, it shall have a low swelling and shrinkage properties. 1.2 For components not exposed to water or weather, and not requiring strength, timber of lower durability may be used.

Quality

The timber used in boatbuilding shall be long-grained and of the best quality, i. e. be free from sap, shakes, objectionable knots and other defects. Twisted-grown or rough saw cut wood shall not be used.

Drying

The timber used shall be well seasoned and sufficiently dried, or shall be correctly dried in a suitable drying kiln.

For this purpose, the timber shall be stacked in piles which are as small as possible, so that uniform drying is guaranteed.

In the case of forced drying, the residual moisture content shall not be more than 10 %. When processing, this content shall not exceed a maximum of 15 % as a result of hygroscopic behaviour.

The moisture content shall be determined by establishing the loss of mass of a sample between its state at the time of draw-off and its state after drying, based on constant weight at 103 ± 2 °C and the calculation of the weight loss as a percentage of the dry mass. This shall be done in accordance with DIN 52375 or ISO 9425.