What are properties of timber deck cargo carried on ships?

Following are properties of timber deck cargo:

1. Stowage factors

2. Friction factors

• Friction is one of the most important factors preventing cargo from shifting. Deck cargo may shift due to a lack of internal friction. Snow, ice, frost, rain, and other slippery surface conditions drastically affect friction. Special consideration should be given to package materials, contact surfaces, and weather conditions.
• Static friction may be used for tight block stowage arrangements as well as for the design of frictional lashing systems such as top-over lashing systems.
• Dynamic friction should be used for non-rigid lashing systems, e.g. loop lashings, which due to elasticity of securing equipment allow for minor dislocation, of the cargo before full capacity of the securing arrangement is reached.

3. Plastic covers.

• Plastic sheeting is often used on packages of sawn wood to protect the cargo. High friction coatings (friction coefficient 0.5 and above) can be incorporated into plastic sheeting as an important means of improving the safe transport of these cargoes.
• Special precautions should be taken to prevent slippery plastic hoods with low friction coefficients, from being used as a sawn wood package cargo covering on deck.

4. Package marking.

All sawn wooden packages should be clearly marked with the volume of the package. The marking should be clearly visible on the top of the package as well as both long sides. The approximate weight should also be shown.

5. Water absorption.

Sea spray may increase the weight of the timber deck cargo and thus influence the stability. The weight increase of the timber varies with time, exposure and type of timber. The value of increased weight of timber deck cargo due to water absorption should be considered in accordance with the 2008 IS Code.

6. Weight of ice.

During cold weather conditions ice may form from sea spray and the stability may be affected as the ice can add weight rapidly. The increase in weight due to icing should be considered in accordance with section 6.2 of the 2008 IS Code. The increases given in section 6.3 of that Code for fishing vessels may be considered to be suitable also for timber cargoes, particularly for small ships. Any increase in weight due to water absorption should be considered before calculating the increase due to the weight of ice.

7. Rigidity of sawn wood packages.