Ultimate Guide to Mooring Operations Best Practices & Techniques

by | Last updated Nov 24, 2023 | Jobs and Tips, Mooring, Shipboard Operations | 0 comments

When a vessel is docked, she is at the mercy of the forces of nature. Wind and current can push her away, which makes it difficult to carry out any type of work. 

To secure her in place, the crew works with shore personnel to perform mooring operations.

A successful mooring operation keeps the vessel securely in place, allowing the seafarers to safely load and unload cargo, or perform maintenance without any issues.

Understanding Mooring Operations

Mooring can be simple or complicated depending on many factors such as the type and layout of the pier, size and design of the vessel, tidal range, weather forecast, currents, and the movement of passing ships.

Understanding these basic elements helps you formulate the type of mooring arrangement you will use, as well as recognize the potential hazards.

What is mooring, and why is it important?

When we talk about ‘mooring,’ we’re actually referring to the method used to secure the vessel to a terminal.

It can be conducted on piers, dolphins, buoys, sea islands, or even with other ships.

If this is made between two ships, it is called a ship-to-ship operation or an STS, which is often made between tankers.

Its purpose is to keep the vessel in place while loading or unloading cargo, bunkering, taking stores or provisions, or performing maintenance.

Types of mooring systems

A mooring system is defined as a set of equipment and techniques used to secure a vessel in place. 

The system typically consists of various components, such as anchors, chains, ropes, and wires. They are used to connect the vessel to a fixed structure, or the seabed.

The most common mooring system is terminal mooring, wherein the vessel is docked in a port.

There are other systems as well, like the ones below.

  • Single Point Moorings (SPMs) involves attaching the vessel to a single point on the seabed using a mooring buoy, which allows the vessel to rotate around the buoy as the wind and current change direction.
  • Multi-Buoy Moorings (MBMs) – use multiple buoys that are usually anchored to the seabed to secure the vessel in place. This is also known as “spider mooring”.
  • Emergency Towing – an arrangement that involves a tugboat or other vessel to tow a disabled or distressed vessel to safety.
  • Tug handling – securing a tugboat using a line made up of wire or synthetic fiber.
  • Barge mooring – a simple way of securing a barge to a pier, locks, or other vessel.
  • Ship-to-ship (STS operation) – involves two or more ships moored to each other. It can be made while underway, at anchor, or in terminals.
  • Specialized mooring – used for securing vessels in particular environments or under specific conditions. Examples are offshore marine operations, where the conditions and requirements can vary widely depending on the sea condition, location, vessel, and cargo.
A shuttle tanker moored to an offshore oil platform with the surrounding seawater on ice.
Oil is also harvested in the polar regions.

Factors to consider before conducting mooring operations

To ensure a smooth and safe maneuvering of a ship in port, these things must be taken into account.

  1. Environmental conditions – the effects of the forces acting on ships such as wind, current, tides, surges from passing vessels, waves, swell, seiche, and ice.
  2. Vessel characteristics – the size, shape, weight, and design construction of the vessel being moored will determine the type and number of lines. The vessel’s draft, freeboard, and center of gravity must also be taken into account, including their changes during cargo loading or unloading operations.
  3. Terminal characteristics – considering the type of fenders, bollards, and other mooring equipment as well as the condition of the pier, range of tide, and seabed.
  4. Safety procedures – since mooring involves hazards, it is important to have clear safety procedures in place. This includes methods for securing and releasing the lines and emergency procedures in case something bad happens.
  5. Crew training – those involved in the operation must be properly trained and experienced in the use of the equipment. 

Preparing for Mooring Operations

Prior to conducting mooring operations, both the ship and the shore terminal should have exchanged initial information regarding the vessel’s designs and the terminal’s layout via email.

This is part of the planning phase. However, the specifics are usually not finalized until the pilot is on board. 

Additionally, it is customary for all equipment to be in good condition before the vessel arrives in port, as part of standard operating procedures.

Ship mooring equipment needed

Using the right tools ensures smooth maneuvering and the safety of the crew.

In general, the equipment needed for mooring operations can be divided into three categories: mooring lines, deck fittings, and ancillary equipment.

Mooring Lines

Mooring lines, also known as mooring ropes, are ropes or wires used to secure a vessel to a fixed point, such as a dock, pier, buoy, or another watercraft. 

There are generally three of these types that you can find on board. These are the following:

1. Wire Mooring Lines

Wire moorings, also known as wires or wire cables, are a type of mooring line that are made up of steel wires twisted together to form a cable. 

They provide strength and durability and can handle heavy loads. You can normally find them on large vessels like the Panamax or supertankers.

Though their service life is longer, the drawback of this type of rope is their weight and flexibility. 

They are very heavy and can be difficult to manage. They can cause back injuries if handled improperly.

Shuttle tanker Jasmine Knutsen moored in a port using wire ropes with rope tails
Image: Flicker.
2. Conventional Fiber Mooring Lines

Also known as conventional ropes or hawsers, they are made from natural or synthetic fibers such as manila, sisal, nylon, or polypropylene. 

Smaller vessels normally use them since they are light, more flexible, and less expensive.

Because of their flexibility, these moorings have greater elasticity, which can be dangerous when snapped.

They are also susceptible to wear and tear when exposed to weather conditions, sea salt, and UV rays.

3. High Modulus Synthetic Fibers (HMSF)

High Modulus Synthetic Fibers are lighter than wires but stronger in terms of strength-to-weight ratio.

A test made by Ropes Direct using High Modules Polyethylene (HMPE) proves that gram-for-gram, it is stronger than steel.

However, it’s not as elastic as conventional ones and requires a mooring tail to compensate for its elasticity.

Deck Fittings

Deck fittings are hardware installed on deck used to slack, heave, secure, or guide the rope to the intended shore bollard.

They are welded with an SWL to avoid using it for excessive loads that may damage them.

Here are the deck fittings used to moor the ship.

  • Mooring winches
  • Bollards
  • Chocks/ Roller chocks
  • Leads/ Fair leads
  • Pedestal Rollers/ Capstan
  • Bitts
  • Cruciform bitts
  • Cleats
  • Rollers
  • Panama Lead

Ancillary equipment

These equipment are used to assist the crew in handling the ropes during maneuvering. They are indispensable and are always included in the preparation.

Most of them are lightweight and portable. 

Examples are given below:

  • Heaving lines
  • Rope/ Wire stoppers
  • Guide hooks
  • Chafing protection
  • Knife or axe (in case of emergency)
  • Hand-held radio
  • Rat guards (optional)

Safety measures to take before, during, and after mooring operations

Mooring operations can be hazardous for crew members involved in the activity, and accidents can occur quickly.

Situational awareness is crucial for ensuring safety during this activity. Although slips, trips, and falls are possible, the most dangerous are the snap back zones.

A crew driving the mooring winch as the ship fasts into the lock.
Controlling the winch to make the vessel fast alongside requires careful coordination between the mooring parties.

What is a Snap Back Zone?

A snap back zone is an area on deck where a line swings or recoils when it fails under excessive tension.

Due to the elasticity of some ropes, their sudden release creates a force so strong that it can destroy or damage things when they recoil.

Here are some safety measures that should be taken before, during, and after mooring:

Before mooring:

1. Crew Briefing: Prior to mooring, everyone is briefed on the specific plan of the operation. As I mentioned before, the entire plan unfolds once the pilot comes on board.

There may also be changes along the way, and this is communicated to the forward and aft stations using handheld radios.

2. Equipment Check: All equipment, including lines, winches, bollards, and fenders, should be checked.

Though they are part of monthly scheduled maintenance, it’s good to have a quick test of them as part of the preparation.

They must also check their handheld radios or walkie-talkie to ensure that their batteries are full, and they are working properly.

3. Risk Assessment: A risk assessment before the operation should be conducted to identify potential hazards.

These hazards must be brought to the crews’ attention to remind them of possible accidents and injuries.

During mooring:

1. PPE: Personal protective equipment (PPE) is a must! Be sure to have your hard hats, gloves, and safety shoes worn.

Dark glasses are also good during broad daylight, and an extra flashlight is a huge help when maneuvering at night.

2. Communication: Clear and concise communication is critical during mooring.

The team leader, the one in charge of the mooring station, must use clear hand signals or voice communication.

In my experience, I always prefer hand signals, especially if the area is very noisy or there is too much interference/ traffic on the radio.

And I always make sure that my crewmates understand the hand signals that I’m using.

3. Safe Distance: People who are not directly involved in maneuvering should maintain a safe distance, or better, go inside the accommodation as snap backs can sometimes be unpredictable.

For those who are directly involved, keep away from the lines, especially if they are in tension. 

Identify snap back zones and make sure you are clear from them. Do not stand or cross over the ropes even if they appear to be slack.

The ship's crew conducting mooring operations with the help of the shore personnel.
The ship’s crew and the shore personnel must coordinate with one another for a safe and successful mooring operation.

After mooring:

1. Equipment Stowage: Mooring ropes and other tools should be stowed properly after use to prevent tripping hazards. This also prolongs their usage span.

2. Inspection: All equipment used during the operation should be inspected, to ensure that they are in good condition, and ready for future use.

It is always a good practice to look for damages in the ropes while securing them to the drum. Damaged ones should be reported and changed as soon as possible.

3. Crew Feedback: Even if the operation went smoothly, it is a good idea to ask your members about things that need improvement for the sake of safety (first) and convenience (second). 

They may discover things like exposed rust on the roller fairlead that’s “eating away” the ropes, or the winch is making unusual noises when heaving up.

Things like these are very important in preventing damage to the machinery.

Team roles and responsibilities

A successful mooring is a team’s effort. It requires cooperation between the master, the ship’s crew, the pilot, tugboats, traffic control, and the shore terminal.

Though some layouts vary between ship types, here are the typical teams, their roles, and responsibilities during mooring operations:

1. The Bridge Team

The bridge team comprises the Master, Pilot, Chief Mate (depending on the company policy), Officer of the Watch, and the Helmsman. They are the command and control center during the whole activity. 

They oversee the movement of each station on the forwards and aft, and the position of the ship against the terminal.

The tools they use in their arsenal are the bow thrusters, main engine, and handheld radio for receiving and sending orders.

2. Mooring Teams

The mooring teams are responsible for handling the ropes, sending them to the shore, connecting and letting go of tugboats, and monitoring their tension during the operation.

There are normally two teams – the forward station and the aft station. Each station has its own members and team leaders, too.

Depending on the size of the vessel, the team may have at least three people – a leader, and two other members.

The leader is usually a licensed officer in the shipboard organization, or a petty officer (Bosun or Pumpman). Their members comprise Able Seaman, Ordinary Seaman, and Cadets.

Two crew securing the loose rope aft into the bitts using the figure of eight during mooring.
Loose ropes must be secured on the bitts in a figure of eight fashion.

3. Mooring Gangs

A ship can not moor by itself but needs the help of people from the shore. 

Shore personnel assigned to assist vessels in this operation are called the mooring gangs. They are responsible for safely securing the lines to the terminal’s bollards.

4. Tugboat

Some ships, especially the large ones, can not effectively maneuver due to their size constraints inside the port. For this reason, they need tugboats to help them dock safely.

Tugboats can either be made fast (tethered) or free to move around. They push or pull the vessel so that it can dock safely and easily.

Tugs receive orders from the pilot on when to push (or pull), how much power they should give, and which part they will assist in maneuvering.

Conducting Mooring Operations

We’ve come a long way in this comprehensive guide, and we’ve discussed quite a lot. Now, let’s proceed with tackling the last part, which is the best technique during mooring operations.

In this chapter, you will learn some helpful tips for approaching a mooring site, deploying and securing the lines, and monitoring your vessel while being moored.

Best practices for approaching a mooring site

  1. Obtain all necessary information about the site, including the layout of the terminal, berth availability, and current regulations in force.
  2. Ensure that the vessel is properly equipped, and the crew is trained to handle the specific requirements of the site.
  3. Establish communication with the shore personnel and the pilot before approaching the terminal or site.
  4. Maintain a safe speed and distance when approaching the mooring site, taking into account the wind, current, and other environmental factors.

Techniques for deploying and making fast

  1. Follow the mooring plan and ensure that the ropes are deployed in the correct sequence.
  2. Use appropriate techniques for securing the lines, such as transferring them to the tension drum, correct turns on the bitts, or using a stopper knot.
  3. Don’t forget to disengage the gears and set the brake to the prescribed settings.
  4. Ensure that the ropes are not tangled or fouled and that they are secured to strong and reliable points on the vessel and shore.
  5. Before making fast the lines, coordinate with the other mooring station, so you can simultaneously heave them. This provides equal tension to the ropes forward and aft, making even the largest tankers firmly alongside.
A huge oil tanker conducting a mooring operation with her two spring lines already on the shore bollard.

Tips for monitoring and tendering the mooring lines

  1. Ask for a printout of the tide table from the officers. This gives you an overview of the movement of the waters in the dock and the height of the tide at specific hours.
  2. Check the ship’s side as part of your safety rounds and make sure it is in contact with the berth. The vessel’s forward or aft could be slightly open so consider this before making any adjustments.
  3. When adjusting the ropes in tension, do it one by one using the winch and not by the brake. Adjust the tension of the lines as needed to maintain the vessel’s position against the jetty.
  4. Do not leave your moorings slack at all times even if there seems to be no wind, current, or tide. A huge watercraft may pass by and “rock your boat”.
  5. Tender the moorings every 30 minutes or one hour, depending on the speed of operation and hourly range of tide. On some ports, you may have to stand by at the mooring station because the water could rise up or fall very quickly!
  6. Aside from tendering the lines, also check for material damage to the equipment and report them to the responsible officer for corrective actions.

Frequently Asked Questions about Mooring

What is the most important part of mooring operations?

The most important part of every mooring operation is the teamwork between the people involved.

They must have clear, concise, and understandable communication whether it be voice or hand signal.

What are mooring duties?

Mooring duties are the task of each crew when mooring. 

Someone must be in charge of operating the winch, handling the ropes, engaging the gears, giving the signal, and in charge of the station.

The duties define the roles of each seafarer involved in the operation.

What are the risks involved?

Trips, slips, and falls are common injuries during mooring, but it doesn’t happen all the time.

The biggest risk involved during mooring operation is when a rope or wire breaks and its recoil hits someone, be it a seafarer or a shore personnel.

The area or zone where the rope follows when it snaps is called the snap back zone.

Identifying the Snap Back Zones on ships.
Snap-back zones.

How can we prevent mooring accidents?

Aside from inspection and maintenance of these equipment, mooring incidents can be prevented through proper training.

Maintaining situational awareness at all times and being prepared for unexpected situations is also helpful.

Crew members must be physically fit and well-rested before the operation, so they can focus on the tasks very well. 

PPE, sufficient lighting, using the right tools, and proper housekeeping in the mooring station will prevent these accidents from happening.

What are mooring arrangements?

Mooring arrangements refer to the setup of machineries, fittings, and lines used to secure a vessel to a dock or other mooring point.

This includes the side on which the vessel should moor, the type and number of mooring lines, the positioning of bollards and cleats, and the layout of the chocks and fairleads.

Generally, when you ask for the ship’s mooring arrangement prior to maneuvering, the captain or OOW’s reply would be, “Starboard side alongside, 3-2-2, forward springs first.”

This means that the ship’s starboard side will be docked at the terminal.

The number sequence 3-2-2 is the arrangement of the moorings starting from head lines/ stern lines, to breast lines, and spring lines. 

The term, “forward springs first” means that the first lines to be sent ashore are the forward springs.

What is your most unforgettable experience during years of mooring operations? Let us know in the comment section if you have questions, so we may address them.

May the winds be in your favor.



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