User Manual
FROG-9
Page13
3.2
Operating Parameters - Sea State
The FROG-9 has an inbuilt damping system which prevents passengers from experiencing shock
loads up to relative landing and take-off velocities of 3.25 m/s (10.5 ft/s). The maximum
recommended sea state, or significant wave height, for the operation of the FROG-9 is determined
by the maximum relative velocity between the FROG-9 (or hook) and the landing deck.
The calculation for relative velocity used here is based on the European offshore crane standard, EN
13852-1:2004. Whereby the maximum anticipated relative velocity between a load and a vessel
deck, is given by the following;
Relative velocity = Hook velocity* + √ (Vessel deck velocity 2 + Boom tip velocity 2)
* Equal to 1.67 m/s (100 m/min, 330 ft/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-9 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 risk of
heavy landings and take-off; dry runs without passengers, landing in centre of deck where less vessel movement,
transfer of fewer passengers to increase damping, hook speed indicator.
Table 1: Recommended Sea States for FROG-9
KEY
Low risk of high landing or take-off velocity and exceeding FROG-9 personnel damping.
Increasing risk of high landing or take-off velocity. Consideration of hook speed and all
other factors is recommended to ensure controlled landing and take-off. A dry run to
gauge risk (without personnel) is also recommended.
High risk of high landing or take-off velocity. Not suitable for routine operations unless
a specific hazard analysis can demonstrate otherwise.
In all cases, adequate planning and risk assessment must be performed.
3.3
Operating Parameters - Additional Factors
Sig. Wave
Height
(m / ft)
Max. Wave
Height
(m / ft)
Fixed
Platform to
Vessel
Semi-Sub to
Vessel
FPSO to
Vessel
Vessel to
Vessel
≤ 1.0
m / 3 ft
≤ 1.9
m / 6 ft
≤ 1.5
m / 5 ft
≤ 2.8
m / 9 ft
≤ 2.0
m / 7 ft
≤ 3.7
m / 12 ft
≤ 2.5
m / 8 ft
≤ 4.6
m / 15 ft
≤ 3.0
m / 10 ft
≤ 5.6
m / 18 ft
≤ 3.5
m / 11 ft
≤ 6.5
m / 21 ft
≤ 4.0
m / 13 ft
≤ 7.5
m / 24 ft
≤ 4.5
m / 15 ft
≤ 8.4
m / 28 ft
≤ 5.0
m / 16 ft
≤ 9.3
m / 30 ft
≤ 5.5
m / 18 ft
≤ 10.2 m / 33 ft
Содержание FROG-9
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