MARICO Marine NZ Limited WELLINGTON HARBOUR PORT AND ...

Report No: 05NZ104 WELLINGTON HARBOUR
Issue: Issue 1.1 Operational Risk Assessment
be mustered reasonably quickly and provide a combined bollard pull of
around 48 tonnes, but this is unlikely to be used at one end of a vessel24. In berthing vessels in winds at the container terminal and Aotea quay, pilots
use the wind shear off a vessel’s hull to provide loading to assist the vessel
coming alongside (or departing) the wharf. This is possible because the
berth is laid out almost in parallel with the prevailing wind (this is from the
northerly quadrant around 60% of the time). However if such a manoeuvre
got out of control in high wind speed, the port simply does not have the tug
power to manage the load created on a high winded vessel, beam on in
extreme wind conditions (conditions that regularly occur). Table 5, below,
shows recommended bollard pull in tonnes to manoeuvre different vessels in
increasing windspeed.
At working
Draught
Windage
(m 2 )
Beam
wind
15 knots
Recommended Tug Bollard Pull Required
Beam
wind
25 knots
Beam
wind
30 knots
Beam
wind
40 knots
Beam
wind
50knots
PCC 199m 5,000 22 67 104 185 289
PCC 175m 4,000 18 34 68 122 130
Large
Passenger
280m
Passenger
220m
>10,000 50 110 160 300 450
5,300 23 45 65 115 180
RoRo 180m 4,100 19 35 72 126 135
Table 5: Windspeed Affect on Bollard Pull Required for Differing Vessels
CentrePort has evolved a speciality for RoRo car carriers, which are getting
larger. Car Carriers are designed to berth starboard side to, resulting in a
difficult downwind manoeuvre to berth a vessel. At time of finalising the
risk assessment, the largest RoRo to be handled at Wellington to date was
programmed25. In most ports, having limited tug power can almost be a “so
what”, because the net affect is that it takes longer to berth and depart.
However, limited tug power also requires recommended limits on moving in
wind speeds that overcome the ability to control the vessel. In the case of
Wellington, this can happen rapidly and relatively frequently.
24
During last cruise season a cruise vessel (SAPPHIRE PRINCESS) operated without bow thrusters and two tugs
were utilised in a forward position.
25
This RoRo Car Carrier is 200m in length, with associated high windage and represents a vessel type set to visit
Wellington regularly.
Greater Wellington Regional Council /
CentrePort Ltd Page 63 of 102