Nayak — Marine Pilotage · Ch. 17: Un-berthing and Outward Manoeuvre

1. Overview — Un-berthing and Outward Manoeuvre

Source: NAYAK, Capt. Santosha K. Theory and Practices of Marine Pilotage. Chapter 17 — Un-berthing and Outward Manoeuvre.

Syllabus: Anexo 2-B, Área II (Arte Naval), item 8 (NAYAK), Cap. 17 — desatracação e manobra de saída. Cross-list Área III, item 6.

As soon as the vessel has finished the purpose of her berthing, she becomes ready for the outward procedures and for un-berthing. The vessel takes the designated minimum time to prepare herself for sailing: besides all the paperwork, the crew secure her for sea, and the main engine and steering are tested for good working condition. When she is ready in all respects, the pilot boards through the gangway or the seaside pilot ladder, assesses the weather and her suitability for sailing, and carries out the master–pilot information exchange (MPiX).

The basic thumb rule is that the un-berthing sequence is exactly the opposite of the berthing sequence, provided the prevailing circumstances are mostly the same. If the prevailing conditions have changed from those at the time of berthing, the sequence need not be the same.

While the vessel is still at the berth, the pilot prevents or minimises unwanted movements until she is clear of all lines and mooring components. All care is taken to avoid damage to the mooring lines, any mooring-related accident, and injury to the crew or the jetty staff. The chapter follows the natural order of an outward move: outward paperwork and information exchange, the un-berthing plan, the outward near-berth manoeuvres, casting off the tugs, the passage out to open waters, and the pilot disembarkation.

2. Outward Paperwork and Information Exchange

After the pilot boards for sailing, the outward paperwork required by the port regulations is completed as the first and foremost job, before proceeding to the real work of manoeuvring. Any pilotage outward certificate or other document that needs the master's signature is completed at the earliest.

The pilot must physically see the Port Clearance before starting the procedure for sailing. If any alternative arrangement is made instead, it has to be confirmed from port control.

Because the inbound pilot may not be the same one handling the outbound movement, the pilot–master information exchange must be carried out in detail, covering all the points discussed under MPiX. The master briefs the pilot on any change in the vessel's condition since the berthing movement. The pilot then plans the passage for the outward manoeuvre, including but not limited to:

the un-berthing plan;
the near-berth manoeuvre;
the speed-control plan;
the expected passage of the vessel;
the tugs' cast-off location;
the pilot disembarkation procedure and location.

3. Un-berthing Plan — Methods of Un-berthing

After the paperwork and the information exchange, the pilot explains the un-berthing plan to the master. The plan varies with each vessel — type, size, manoeuvrability and displacement — and depends largely on the prevailing weather. Several methods are available.

3.1 Parallel method — large vessels in calm weather

This method uses a parallel movement of the vessel with two tugs, one at the bow and one at the quarter, for large vessels of high displacement. While the tugs keep pushing the vessel onto the berth, all the head and stern lines are cast off and taken on board. Then the forward and aft spring lines are cast off simultaneously, so that no spring exerts a longitudinal tension that would move the vessel. Once all the lines are on board, the two tugs — one at the bow and one at the stern — pull the vessel off the berth while keeping her parallel to it, until she is well clear of the nearby obstructions. This keeps her clear for any swings or lateral movements in the near-berth manoeuvres, and it suits heavy vessels because their response to any external force, tug push or pull is slow.

Fig. 17-1 Parallel un-berthing of a large vessel with two tugs. Panel (a): vessel alongside with two tugs on the offshore side, forward and lateral pairs of references marked on the berth and an arrow showing her moving off. Panel (b): vessel already pulled off parallel to the berth, with a slight ahead vector on the bow.

As the tugs start pulling, the vessel gains a marginal ahead or astern speed and may come dangerously close to another vessel berthed nearby. Keep quick engine commands ahead and/or astern always on the cards to kill this marginal speed and hold the fore-and-aft position.

Good practice: if the large vessel has a bow and/or stern thruster, use the tugs minimally or avoid using them to pull her off, since the thrusters generate no marginal longitudinal speed while she moves away from the berth.

3.2 Un-berthing with a stronger offshore breeze

When an onshore or offshore wind is present, the pilot makes the best use of the wind to control the lateral movement away from the berth. With an offshore wind, once all the lines are cast off the vessel comes off the berth automatically as the tugs stop pushing and stand by to pull. With an onshore wind — whose effect is greatest at the accommodation — it is difficult to pull the stern out; if the stern does not come out, the forward tug may need to push the bow to get a better effect from the aft tug.

3.3 Un-berthing with a strong head wind or current

When a strong head or stern wind or current tends to move the vessel longitudinally along the berth if let free, one set of spring lines — forward or aft — stays under stress and tight while the other set stays slack. Here the head and stern lines are cast off first. Then the loose springs are cast off, holding on to the tight springs that hold the vessel against the wind or current. The bow is pulled out a little; slowly the stern also comes off; finally the remaining springs are cast off and the vessel is moved off the berth.

3.4 Close clearances — small vessels, one tug, with a stern wind

This method suits smaller and lighter vessels, and developing ports with no tug or only one. The single tug is made fast on the bow. All head and stern lines and the stern spring are cast off, holding on to only the forward spring. Once the lines are on board, engine is given ahead and helm away from the jetty, which brings the stern away from the berth. Once the stern is clear, engine is stopped and helm put amidships; then the spring is cast off and the tug pulls the bow immediately away from the berth.

3.5 Close clearances — small vessels, one tug, with a head wind

This method also suits smaller and lighter vessels in developing ports with no tug or only one. The single tug is made fast on the bow. All head and stern lines and the forward spring are cast off, holding on to only the aft spring. Assuming right-hand fixed-pitch propellers, the pilot then follows these steps:

Port side alongside: engine astern with helm amidships brings the bow away from the berth while the stern rests on the fenders. Starboard side alongside: engine astern brings the stern off while the bow rests on the fenders.
The bow tug slowly pulls the bow as required to keep it away from the berth; for a starboard-side alongside this brings the vessel out of the berth.
Once the bow is well clear, engine ahead with helm towards the berth brings the stern away (for a port-side alongside).
This slacks the aft spring, which is cast off immediately; the stern comes out and the vessel steadies on her course.

Whichever spring is held decides which end opens first. The following table summarises how the springs are used to spring one end off the berth.

Spring held on	Engine / helm applied	Effect on the vessel
Forward spring (stern wind)	Engine ahead, helm away from the jetty	Stern springs off the berth; then stop, helm amidships, cast off spring and the tug pulls the bow out
Aft spring — port side alongside (head wind, RH FP prop)	Engine astern, helm amidships	Bow springs off the berth while the stern rests on the fenders
Aft spring — starboard side alongside	Engine astern, helm amidships	Stern springs off the berth while the bow rests on the fenders; vessel comes out of the berth
Tight springs (strong head/stern wind or current)	Loose springs cast off first, hold the tight ones against the flow	Bow is pulled out a little, the stern follows; then cast off the remaining springs

Method	When it is used	How it is done
Parallel (two tugs)	Large, high-displacement vessels; calm weather	Tugs at bow and quarter; head/stern lines off, springs off simultaneously; pull off parallel until clear; kill marginal speed by engine
Offshore breeze	Offshore (or onshore) wind present	Offshore wind: lines off, vessel comes off on her own; onshore wind: fwd tug pushes bow to help aft tug take the stern out
Strong head wind / current	Wind or current moves her longitudinally if free	Head/stern lines off, loose springs off, hold tight springs; pull bow out, stern follows; cast off remaining springs
Small vessel, stern wind	Small/light vessel, one tug, developing port	Hold forward spring; engine ahead, helm away → stern off; stop, helm amidships; cast off spring, tug pulls bow out
Small vessel, head wind	Small/light vessel, one tug, developing port	Hold aft spring; engine astern (RH FP prop) to open one end; bow tug pulls; engine ahead/helm to berth; cast off aft spring
Double banked	Two vessels made fast side by side	Head/stern lines off, hold springs; cast off inner springs; both tugs pull parallel to the fenders; then manoeuvre away

3.6 Un-berthing from double-banked vessels

In double-banked vessels the situation is very precarious, as there is always a chance of metal-to-metal contact between the ships. Some Yokohama fenders between the vessels maintain a marginal distance, but how well that distance is kept depends on the number, size and condition of the fenders in use.

Fig. 17-2 Un-berthing of double-banked vessels: two ships side by side with Yokohama fenders between the hulls; the left vessel still against the berth with springs, the right vessel already pulled off by a tug with a traction vector directed away.

The head and stern lines are cast off first, holding on to the springs forward and aft. If tugs are used, they must avoid pushing the vessel onto the Yokohama fenders. Once the head and stern lines are on board, the springs are cast off from the inner vessel; once all lines are clear, both tugs pull the vessel parallel to the fenders, and once sufficiently clear she is manoeuvred away.

Precautions for double banking: make best use of the wind; clear away from the fenders slowly; any angle may cause metal-to-metal contact between the ships; while touching the fenders do not gain any forward or aft speed, as it may break their lines; and if tugs are used, use them judiciously.

4. Outward Near-Berth Manoeuvres

After the vessel is cast off and brought to a safe distance from the berth, clear of all obstructions, the pilot starts the near-berth manoeuvring to move her away safely while holding a bare minimum speed.

4.1 Turning in front of the berth

If there is sufficient space in front of the berth, the vessel is turned right there, so as to avoid any astern movement. Turning in front of the berth lets her take advantage of ahead engine and steering for the rest of the outward passage without further use of tugs. It is easier and quicker to manoeuvre ahead than astern over a given distance in the harbour, because astern engine power is less, it is coupled with transverse thrust, and no steering is available when moving astern.

Fig. 17-3a Turning in front of the berth: a "Minimum Safe Distance from berth" dimension is marked; the vessel swings through successive positions in front of the berth, tugs assisting bow and stern, with the dashed track of the turn.

Here the bow tug pulls the vessel to generate a turning swing. The pilot's reference is the berth itself: the vessel maintains a safe distance from the berth while turning, and her stern is kept at a pre-calculated distance so that she is always in safe waters.

4.2 Moving astern to the turning basin

If there is not much space in front of the berth, the vessel is turned at the turning basin and moves astern towards it from the berth. She travels astern all the way from the turning basin to (and from) the berth. Once near the berth, a parallel, acute-angle or obtuse-angle approach is used to bring her alongside to pass the mooring lines. The typical features are that the vessel moves stern-first all the way from the turning basin to the berth, and that the stern makes the approach earlier than the bow.

Fig. 17-3b Moving astern to the turning basin: a sequence Pos-1 to Pos-4 of the vessel leaving the berth and progressing stern-first along the channel between dashed boundary lines, tugs at bow and stern; at Pos-4 she completes the turn in the basin.

4.3 Offshore-anchor lateral approach

This special operation uses one anchor when the circumstances are not suitable for a tug-guided move in a port with under-developed infrastructure — a strong current at the berth, insufficient sea-room to keep engines running for long, no tugs available, or a wind or weather suitable for a controlled drift (an onshore breeze). The pilot follows the reverse sequence of the steps used when berthing with the offshore anchor.

All head lines and forward springs are cast off while the anchor is engaged and pulled up a few links, to swing the bow away from the berth while keeping the cable on a moderate-to-longer stay if required. Then the aft springs and stern lines are cast off to clear the berth. Meanwhile the helm is put hard to port and a kick ahead on the engines takes the stern away from the berth while the vessel gains a marginal ahead speed — all the while keeping hearing on the anchor cable. Until the anchor is aweigh, the vessel keeps using her engines and helm to hold her stern off the berth.

Fig. 17-4 Lateral un-berthing using an offshore anchor, in two steps. (a) The anchor, laid offshore, is engaged and hove up a few links to swing the bow away from the berth. (b) Helm hard to port and a kick ahead take the stern off the berth, the cable tending to the anchor leading the vessel out.

4.4 Cold move — towing with the engine inoperative

A cold move is sometimes planned for un-berthing a vessel with the engine under repair or in an emergency; sometimes it becomes necessary unexpectedly if the engine fails in the middle of a manoeuvre.

Fig. 17-5 Cold move under tow (engine inoperative): the vessel alongside assisted by tugs — one on the bow on a dashed tow line acting as propulsor and others giving lateral assistance, with traction vectors directed off the berth.

In any case, at least three tugs are required for a safe cold move. One tug acts as the propulsor — made fast at the centre lead forward or at the aft of the vessel; the aft position, where situations permit, is more useful for its ability to pull and push from right astern. The other two tugs assist the bow and stern for any swing and lateral movement.

A short tow-line arrangement is made for the propulsor tug where possible, to get better control of the vessel in a planned cold move. In an emergency, when time is critical, only a single tow line is sufficient.

5. Casting Off the Tugs

Casting off the tugs after the outward manoeuvre is a critical decision that must be well timed and done at the correct location. It has to be timed so that the vessel is free of any danger in proximity.

Before the tugs are cast off, the vessel's speed must not exceed a safe limit — above it, it is unsafe for the tugs to operate alongside — and must not be below a safe limit either, or the vessel is left at the mercy of external forces with no tug assistance. If she gains more than the safe speed, a tug may get "glued" against the ship's side by interaction and struggle to move away; the tug must then report to the pilot to reduce speed for a safe cast-off.

The tug line should be slack enough for the ship's crew to handle easily, and preferably not slacked into the water, which adds drag and greatly increases the rope's weight. While casting off, the stern tug must beware of the transverse thrust from the propeller wash, especially in light condition. Casting off from large vessels in light condition is harder still, because the height of the deck above the sea prevents the tug from communicating with the crew; the pilot then takes extra care and ensures the operation is carried out in communication with the master.

6. Out to Open Waters and Pilot Disembarkation

6.1 Manoeuvring out of the harbour to open waters

The outward manoeuvre is no different from the inbound manoeuvre except for a few minor differences. The loading condition, and thus the displacement, may differ (except for vessels that came only for bunkering or a similar purpose), and there may be marked changes in the drafts. The vessel faces more and more open water as she moves out. Where the inbound plan calls for speed reduction, the outbound plan is a speed-increase plan. After casting off, the vessel starts securing and getting ready for sea; the tugs are cast off while she is moving.

All the navigational marks now lie on the opposite side of the vessel, and the fixed land references used for positioning are no longer constantly visible as she moves out of the port. Even with these differences, the basic principles of manoeuvring in restricted waters remain the same throughout.

6.2 Pilot disembarkation

Once the vessel is in safe waters and the master is comfortable to navigate without further advice, the pilot gets ready for disembarkation. The pilot boat is contacted and told which side the pilot ladder is rigged. The master adjusts speed so the pilot boat can manoeuvre alongside without difficulty, and alters course to give a good lee to the pilot boat, settling on a preferable course and speed for a good disembarkation.

It is advisable to stop the engines just before the pilot lands on the ladder, so the propeller is not running while the pilot is hanging on it. Should the pilot fall into the water during transfer, the propeller must not pose a threat to life. The rest of the procedure is similar to safe pilot embarkation.