0027/nd guidelines for Marine Lifting and Lowering Operations

4.3 
APPROVAL OF MOORINGS 
4.3.1 
A lift may normally be considered a weather- restricted operation. Limiting weather conditions for the 
lift operation shall be defined, taking into account: 

the weather forecast reliability and frequency for the area 

the duration of the operation, including a suitable contingency period 

the exposure of the site 

the time required for any operations before or after the lift operation, including crane vessel and 
transport barge movements. 

currents on the lifting vessel/transport barge during the lift. 

currents on the lifted structure during lowering through the water column. 
4.3.2 
An approval of a lift will normally include the approval of the crane vessel and transport barge 
moorings in the limiting design weather conditions specified for the lifting operation. When operating 
alongside an offshore installation, procedures should be submitted which show that the crane vessel 
and transport barge can and will be removed to a safe distance when the weather conditions exceed a 
specified level. An approval of a lift does not include approval of the vessel moorings in extreme 
weather conditions. 
4.3.3 
Similarly, an approval of a lifted load-out will include the approval of the crane vessel and transport 
barge moorings at the load-out quay in the limiting design weather conditions specified for load-out. It 
does not necessarily include approval of the crane vessel and/or transport barge moorings in extreme 
weather conditions. Note that for approval of load-outs, reference should also be made to 0013/ND - 
Guidelines for Load-Outs, Ref. [2]. 
4.3.4 
Additionally, and if specifically requested, GL Noble Denton will study and issue an approval of the 
moorings of the crane vessel or the transport barge, for a more extended period.