In case where the damage stability calculation for ships carrying timber deck cargoes is made in accordance with Chapter II-1 of SOLAS, the buoyancy of the timber deck cargoes could not be taken into account in that calculation up to now. But, IACS decided that the buoyancy of timber deck cargoes shall be taken into account in the damage stability calculations and adopted the unified interpretation, UI SC 161, concerning to this issue on 25 April 2000 at IACS Council. This UI SC 161 will enter into force from 1 January 2001.
However, the extent of buoyancy of timber deck cargoes that may be taken into account in the damage stability calculations shall be followed as stated below for the longitudinal and transverse direction. (Please refer to the "Figure 1".)
1. Longitudinal direction
The buoyancy of only one standard superstructure height of timber deck cargoes may be considered in spite of the buoyancy of the height of timber deck cargoes actually stowed on board the ship. But, the buoyancy of timber deck cargo within the longitudinal extent of damage is to be ignored in the damage stability calculation.
2. Transverse direction
The buoyancy of timber deck cargo within the longitudinal extent of damage is to be ignored from side to side.in the damage stability calculation at any of transverse damage extent.

Therefore, in case where the timber cargoes are loaded on upper deck, allowable loading capacity of timber cargoes will be increased as compared with the present loading capacity, as a curve of limiting G0M for timber load line can be created separately.

In detail, please refer to the attached UI SC 161.
Department in charge: Hull Department
Tel. 03-5226-2018
Fax. 03-5226-1019
Attachment:1. IACS UI SC 161
2. Extract of IMO Resolution A.715(17), Chapter 3