GUIDELINES FOR MARINE LIFTING & LOWERING OPERATIONS 0027/ND Rev 11 Page 17 of 84 Term or Acronym Definition Weather restricted
operation
A marine operation which can be completed within the limits of an
operational reference period with a weather forecast not exceeding the
operational criteria. The operational reference period (which includes
contingencies) is generally less than 72 hours.
The design environmental condition need not reflect the statistical
extremes for the area and season.
An alpha factor shall be accounted for in defining the design environmental
condition. See Section 7.4.8 of 0001/ND, Ref. [1].
Weather unrestricted
operation
An operation with an operational reference period greater than the reliable
limits of a weather forecast. The operational reference period (which
includes contingencies) is generally more than 72 hours. The design
weather conditions must reflect the statistical extremes for the area and
season.
The design weather is defined in Section 7.3 of 0001/ND, Ref. [1].
WLL /
Working Load Limit
The maximum force which a product is authorised to sustain in general
service when the rigging and connection arrangements are in accordance
with the design. See SWL.
WSD
Working Stress Design (effectively the same as ASD)
GUIDELINES FOR MARINE LIFTING & LOWERING OPERATIONS 0027/ND Rev 11
