Rev 1.0
9
3
Operations
3.1
General
A range of factors affect the risk of conducting marine personnel transfers which can be
broadly grouped into;
▪
equipment factors
, e.g. carrier type, crane specification, vessel specification.
▪
environmental factors
, e.g. wind and wave, visibility, temperature, precipitation.
▪
personnel
, e.g. skill, experience, awareness, and training.
▪
operational and management
, e.g. risk assessment, planning, communication etc
The most important of these factors is management; without appropriate assessment,
planning, and implementation of operations there cannot be control of the other factors and
risks.
For more detail RML recommend the Marine Transfer Forum
’s guidelines on personnel
transfer by crane, which can be downloaded, from
document contains comprehensive guidance and information to assist in performing safe
personnel transfer operations.
The following sections of this chapter contain specific operational guidance relating to the
WAVE.
Sea State
Passengers riding the WAVE are secure by the restraint assembly. Protection from shock
loading is provided through the polymer landing feet and passengers adopting the
recommended brace position. The maximum recommended significant wave height for
WAVE operations is derived from the maximum relative landing and pick-up velocity
between the load (carrier) and the deck. A relative landing speed of 2.14m/s has been
validated in testing.
The calculated operational sea states detailed in Figure 2 are based on vertical impact
speeds and bio-mechanical considerations. They reflect the ability to withstand such
impacts with minimal risk of injury to the human body. However, there are many additional
factors that may affect the safety of crane transfer operations. These include vessel station-
Technical note:
The calculation for relative velocity used here is based on the European offshore crane standard,
BS EN 13852-1:2013. Whereby the maximum anticipated relative velocity between a load and a
vessel deck, is given by the following;
Relative velocity = (0.5*Hook velocity)
1
+ √ (Vessel deck velocity
2
+ Boom tip velocity
2
)
1
Equal to 1.67 m/s (100 m/min) for lifts below 5 tonnes. Higher crane hook speeds may be available, and it follows that
the higher the available crane speed the higher the possibility of a heavy landing or take off. However, with a qualified
Crane Operator, it is considered unlikely that the FROG-XT will be landed at full hook speed on a deck rising at full speed.
If there are concerns about heavy landings, operators may wish to consider the following methods to reduce risks; dry
runs without passengers, landing in centre of deck where there is less vessel movement, transferring fewer passengers
to increase damping, using a hook speed indicator.
