Manoeuvre Nr. 1 – Container Vessel



For this example, we consider a container vessel:

  • 250-metres long,
  • Single propeller right-handed fixed pitch,
  • 2000 HP bow thruster,
  • Good weather conditions,
  • Turning basin about 500 metres,
  • Starboard side alongside at the assigned berth.

In reality, one tugboat would be sufficient to moor in good weather conditions for a ship with these characteristics without deficiency and supposing the tug use its towing line. Still, we consider using two for practical-educational purposes.

How do we use these two tugs?

For the aft one, there’s no doubt: fastened through the centre lead, using the tug’s line. It is because it will help slow the ship’s speed, help in turning and stopping, and, lastly, it will be ready to control the ship’s stern swinging during berth approaches.

As for the fore tug, we can choose whether to make it fast, keep it pushing or decide on a “hybrid” solution. When the experience in manoeuvring does not have solid foundations, it feels relaxed if the tug is firmly secured to the vessel. With the improvement of the ship-handling experience, the tendency is to use the forward tugboat to push. Let’s see why:

  • The tug operates under the forecastle on the starboard side at the beginning of turning. If secured, it would work more forward with a better yield, but most of the time, the vessel would also be dealing with an unwanted forward pull component.
  • If the goal is not to advance, due to the pivot point moved forward, the stern turning moment is more important and influential than the forward one, so it is the aft tug.
  • Versatility: keeping the tug pushing means fast positioning it where it is most needed.
  • Moreover, it will be a moment when the ship has to be brought to the quay; the fwd tug towing on a line can operate in pulling mode as long as the length of the towline allows it. Then it has to move outside. On the contrary, if the fore tug operates at a ship’s side, it can be transferred to the centre ship, pushing her slowly toward the quay. At the same time, the stern tugboat and the bow thruster are still ready to keep her parallel slow down the transverse approaching velocity. We must also consider that the mooring boat cannot pick up the mooring lines as long as the eventual fore tug pulls towards the quay. Problem solved if the tugboat works at a ship’s side.

Let’s describe what happens:


First Phase

The ship’s speed over-ground doesn’t need to be high in good weather conditions. Once close to the entrance, the vessel can slow down speed further and the stern tug secured. The second tug must follow the ship close to its starboard quarter.

Second Phase

We adjust the headway to get to the swinging spot with about 3 knots navigation speed. The goal is to enter with a velocity that allows us to slow down adequately by stopping the engine proceeding with the ‘residual speed’; to do this, we have three options:

  • If the ship’s speed is still too high, but we have secured the aft tug in time, we use it to slow down;
  • If the tug is not ready, and the speed is relatively low, we can put the rudder alternately hard over to one side and the other; an operation which will not affect the ship’s heading, but will cause the speed to decrease;
  • If the tug is not secured yet and the ship’s speed is too high, we can use the engine astern to drop the speed rate. In this case, before intervening with the machine, it is advisable to put the rudder hard over to the port for a consistent time to counteract the propeller’s paddle-wheel effect that will come.

Third Phase

The turning can be clockwise or counterclockwise. In general,  this decision is influenced by several factors. Let’s see what they are:

  • In the presence of side wind to push towards the quay, it is advisable to turn with the “head to the wind”, therefore clockwise, always to maintain a windward position; in this case, it is possible to reach the swinging spot even with a higher speed, as the favourable paddle-wheel effect of the propeller in reverse gear facilitates the turning;
  • In the presence of side wind to widen from the quay, it is advisable to swing counterclockwise, always respecting the principle to keep the “head to the wind”; in these conditions, we may arrive at the turning point with low speed to get the chance to use an engine kick ahead to go upwind and facilitate the swing;
  • In the case of no wind, the choice depends more on personal tastes.

However, we can always make some considerations:

  • We can swing in any direction if we must moor between two vessels with a stern tug secured and a second tug ready to push. The pushing tugboat will take us alongside without too many difficulties, whatever the effect of the propeller is. If only one stern tugboat is available or no tug at all, it is better to swing clockwise, taking advantage of the paddle-wheel effect. This sense of rotation also allows us to have the stern close to the quay and, therefore, the opportunity to easily send a stern line ashore; it will then be also easy to control the bow using the bow thruster.
  • If the pier is clear and there is much room available, we can swing in both directions again, but it can be faster and easier to turn anticlockwise. With fine-tuned speed, the swinging will occur with a forwarding headway and the pivot point positioned forward of the centre. It will facilitate the rotation of the stern – which must cover the widest arc- allowing us to continue to use the engine and the rudder to optimize the manoeuvre.

In the anticlockwise turning, we have several possibilities in the use of the tugs:

Tug secured forward centre lead

About 3 knots headway. When we reach the swinging basin, we put the rudder hard-a-port. With the engine stopped, the swing will be slow. The stern tug begins to work at the starboard beam. During the rotation, the bow, compared to the stern, will cover a minimal arc of a circle. If the speed ahead is too high or the stern swinging is too slow, we can use the forward tug, which will pull on the port side. However, the fore tug will work pulling for a short time because the ship’s bow will tend to move out from the quay at a certain point in the turning. We may counteract this behaviour using the bow thruster to starboard or, if necessary, the forward tug transferred to pulling on starboard or used push-pulling style on the port bow.

This choice mainly depends on the weather condition. In good weather would be preferable to have the tug towing on a line till necessary; it can be ready to stop the approaching velocity if BT fails or can be released to work pushing in any position at the ship’s side. In against gust windy condition would be preferable to have the tug ready to push&pull the bow as needed. However, since the tugboat is secured on the Panama lead, the switch from push to pull takes longer due to the ship’s anchor, which often interferes with the manoeuvre. The stern tug will work angled towards the quay: in this way, we will have a component to stop the ship, pull the stern to the pier, and the Push-Pull tug to control the bow.

Tug pushing forward.

In the initial swinging phase, the tug will help the bow thruster, if necessary, push from the starboard side to move the bow to the port. The next step will move the tugboat to the port side to help the bow thruster keep the bow close to the quay; in the third phase, we will shift the tug in the centre to accompany the ship into position.

Tug pushing aft

This solution is not often used, although it is very effective, especially when handling heavy draft vessels. We make fast one tug aft to control the ship’s speed while keeping a second tug to push the stern for turning. Before turning, we direct the bow to the centre of the final mooring ship’s position.

We move the tug to push on the aft quarter port side and the one secured to pull the stern abeam to starboard.

Together with the bow thruster, tugs help to counter the bow’s tendency to move out from the quay.

What’s the benefit?

The stern rotates quickly, describing a vast arc of circumference, while the bow rotates slowly. Due to the stern tug brake component, the headway significantly decreases so much that we have to use the engine ahead to compensate.

Considering the lateral speed acquired, we stop the tugboats in time, positioning the towing on a line tug outwards, ready to widen. We move the stern pushing tug to the centre to softly bring the ship into position, adjusting the approaching lateral velocity.

Tug make fast to the port-bow- Push&Pull.

We can make it fast in the port-bow position and use it to pull when needed (particularly in the first phase of the turning and in the final mooring phase, where we adjust the approaching velocity to the quay). In contrast, it can lean against the hull in the forecastle area to push when required by shortening the line. We have defined this solution as “hybrid” because it undoubtedly offers advantages and limitations compared to the others. Meanwhile, we can say that it is difficult to use this system at the stern. It is due to the hull’s marked shape, which often does not allow the tug to lean on without risking colliding with its superstructure.

Moreover, switching from “push” to “pulling” is not immediate, but anyway, faster than what is needed when the tugboat is secured in the centre Panama lead. By choosing this option, the steps of “making fast the tug and letting go” during the manoeuvre remain to be carried out if needed to move it to the ship’s centre to accompany in the final phase to the quay. Nevertheless, it is advantageous in the case of widening beam wind. Indeed, in the event of a sudden bow thruster failure, the push&pulls allows managing the problem with some tranquillity.

Speaking of container ship manoeuvres, the video we propose here, presented on our YouTube channel, should be interesting.