(a) Timber deck cargo. The term “timber deck cargo” means a cargo of timber carried on an uncovered part of a freeboard or superstructure deck. The term does not include wood pulp or similar cargo.

(b) Timber load line. A timber deck cargo may be regarded as giving a vessel a certain additional buoyancy and a greater degree of protection against the sea. For that reason, vessels carrying a timber deck cargo may be granted a reduction of freeboard calculated according to the provisions of § 42.25-20 and marked on the vessel's side in accordance with the provisions of § 42.13-30(c) and (d). However, in order that such special freeboard may be granted and used, the timber deck cargo shall comply with certain conditions which are laid down in § 42.25-15, and the vessel itself shall also comply with certain conditions relating to its construction which are set out in § 42.25-10.