MARICO Marine NZ Limited WELLINGTON HARBOUR PORT AND ...

Report No: 05NZ104 WELLINGTON HARBOUR
Issue: Issue 1.1 Operational Risk Assessment
basis of the passage plan and it is recommended that exempt vessel passage
plans follow recommended tracks to provide consistency. If all such
operators were required to submit passage plans and subsequent
amendments, then the Harbourmaster system would be able to assist
individual plans conform to the recommended track system.
11.3 UNDERKEEL CLEARANCE AT THE ENTRANCE
CentrePorts’ Standard Operating Procedures for pilotage focus on underkeel
clearance (UKC) as a key factor limiting vessel movement. A static channel
clearance of 1.5 metres UKC and 0.9 metres at the berth is set (although it
appears this may be exceeded at the Marine Manager’s discretion33 ). Any
vessel with a draught greater than 9.8 metres is likely to navigate with
minimum UKC, given the controlling depth of 11.3 metres in the channel.
SOP’s require pilots to consider tidal height and influence of changes in
barometric pressure in UKC calculations.
A conservative UKC formula is used to calculate squat thereby providing
additional safety margin. An Operating Note additionally provides pilots with
guidance on the loss of UKC expected through pitching and rolling. A
remote tide gauge at Queens Wharf is available for obtaining actual height
versus predictions at any time.
It would be useful to determine if there is any tidal gradient between the area
of tidal flow restriction near the Front Lead and Queens Wharf. A tide gauge
situated on the Front Lead would provide, assisting with passage planning of
deep draught vessels. Further risk control by provision of real time wave
and tidal height data in the entrance is tabled in section 13.7.3.
11.4 WIND AND FOG LIMITATIONS
Prescribed wind limits are only in force for tankers but the deployment
location of container cranes which have ceased operation in winds over 40
knots may also stop movements on or off the berth.
Departure in fog is permitted but deep draught vessels and tankers require a
minimum of 0.3 cables visibility. Arrivals are more restricted and different
limits are set relating to vessel length, draught and for tankers.
33 This is done on one off situations and involves consideration of the vessel, cargo, pilot skill, swell and risk factors.
Procedures make reference to liaison with the Harbourmaster and inn practice it is unlikely that the marine
manager would take such a decision without Harbourmaster involvement. The limit is also close to the commonly
accepted rule of thumb value of 10% static UKC.
Greater Wellington Regional Council /
CentrePort Ltd Page 74 of 102