How do tugboats work? (2024)

Tugs are special boats that assist other vessels into and out of port. The primary purpose of these boats is to help move larger ships by towing, pushing, and guiding. Many even have fire suppression and other systems to help the larger ships. But how is it that these seemingly tiny tugs move boats a thousand times their size, and why can’t those boats move themselves? Let’s take a look at what makes tugs special, and why they’re an integral part of shipping.

How do tugboats work? (1)

Image Credit: MarineLog

Why are tugs needed?

Tugs fill a few different roles:

The last role is usually the largest, but why do large ships need help getting into and out of port? It’s easy to maneuver a large ship at sea, they can keep up speed and have plenty of room to adjust course. The larger ships grew, the more they could carry long distances, but the less agile they became at low speeds and in tight spaces. Moving sideways is particularly difficult for vessels that can be hundreds of meters long. Often, when huge vessels like container ships and LNG ships get close to port, they are escorted by a tugboat, ensuring they take the safest route. Once in port, it’s again up to the tugs to take them on the last leg of their journey.

How do they move large ships?

Depending on the size of the ship and the tugs, once in port, one or more tugs can tow via a tow line or push the ship into dock. At low speeds, large vessels don’t have enough water passing over the rudder to turn quickly, so this assistance is needed for the final mooring of the ship, especially in crowded ports. The tow line can be used for direct or indirect towing. With direct towing, the tug is pulling the vessel straight ahead, likely due to the ship not having the ability to propel itself. With indirect towing, the tug can act as a rudder and pull the ship to one side, helping rotate the ship as it moves. Of course, tugs can also cruise right up to the side of the ship and push. Large ships usually have designated areas where tugs can push safely.

How do tugboats work? (2)

Image Credit: Workboat

What are the types of tugboats?

Tugboat designs have changed over the years, the oldest being the conventional tug. These are in use all over the world and consist of a diesel engine and have one or multiple propellers. They use a screw propeller design with nozzles and rudders that move to help them maneuver. The benefits to a conventional tug are that they are simple, low maintenance, and have a proven design. Downsides are they do not have the performance of new tugs, some only go in one direction, they are more prone to capsizing, and can’t work with the largest ships. They are very reliable and still in use today.

The tractor tug is next up, it uses a “2-multidirectional propulsion unit, of which some are rather like large rotating outboard motors with other consisting of rotating vertical blades,” according to Marine Insight. These are more versatile and agile compared to conventional designs. They can provide 360 degree thrust, have low risk of capsizing, and can work sideways. Downsides are less pull compared to newer ASD tugs, high maintenance cost, and complexity.

Azimuthal Stern Drive (ASD) use some of the benefits of both the conventional and tractor tugs. They have two towing locations and use two rotating azimuth units for propulsion. Benefits of these tugs are lots of bollard pull, shallow draft, and better stability at speed. Downsides are they are a little more complex to control and limited in some maneuvers. You can see a tugboat with azimuth thrusters in the photo below.

How do tugboats work? (3)

Image Credit: Reddit

Most tugboats are still powered by diesel engines. Many newer and larger tugs have two diesel engines, some with a combined total of over 6,000 horsepower! There are also hybrid tugs that combine diesel and electric power, and LNG-powered tugs.

Are there electric tugs?

Yes! In September 2020, the first fully electric tugboat went to work in Istanbul. ZEETUG, which stands for Zero Emission Electric Tug boat, built the Gisas Power, owned by GISAS Shipbuilding. It operates in the Port of Tuzla Aydınlı Bay, where environmental and navigational needs drove the demand for the electric tug. Plugboats has specs on the Gisas Power, “The Gisas Power has an overall length of 18.7 metres • 61 feet, a beam of 6.7m • 22′ and 32 tonnes of bollard pull (BP), which is how the power of tugboats is rated. Different tugboats are designed for different jobs, but the ‘average’ tug has a BP rating of about 40-45 tonnes and the strongest are rated at 60-65T BP.” ZEETUG’s electrical propulsion system can be built to specifications from 5T BP all the way up to 75T BP. The ZEETUG-30 is the first all electric tugboat - it gets power from two 1,450kW battery packs that are located separately, forward and aft, and air-cooled. More electric tugs and even hydrogen tugs are on the way.

How do tugboats work? (4)

Image Credit: PlugBoats

What about Autonomous tugs?

There are autonomous tugs too! In March 2020, Wartsila and PSA completed initial sea trials with an autonomous tugboat for the IntelliTug project. The PSA Polaris was retrofitted for autonomous navigation and tested to ensure it could avoid virtual and real-life obstacles. They are continuing R&D on the new tug throughout 2020.

How do tugboats work? (5)

Image Credit: Splash247

As you can see, tugboats are an important part of getting large ships into and out of port, through dangerous situations, moving all types of non-powered or disabled vessels, firefighting, and even search and rescue. Check out the video below for a day in the life of a tug operator in Dublin Port.

Video credit: Dublin Port Company

Sources:

How do tugboats work? (2024)

FAQs

How do tugboats work? ›

Tugboats are designed to pull barges by using powerful engines and specialized propulsion systems. Tugboats come in different sizes and shapes, depending on their intended use and the size of the barges they will tow. Some tugboats are designed with a single propeller, while others have two or more.

How can tugboats pull so much? ›

Massive engines capable of powering three propellers on a relatively small vessel gives the typical tug a PWR of 9.5 or so—over 8 times the PWR of a container vessel. The propellers, engine, and low draft combine to create a high “bollard pull,” a measurement of thrust.

How do tugboats operate? ›

Modern tugboats often employ advanced propulsion systems such as azimuth thrusters or Z-drives, which allow the propeller to rotate 360 degrees. This feature gives tugboats exceptional maneuverability, enabling them to change direction swiftly and perform complex maneuvers with precision.

Do tugboats push or pull? ›

With indirect towing, the tug can act as a rudder and pull the ship to one side, helping rotate the ship as it moves. Of course, tugs can also cruise right up to the side of the ship and push.

Why are tugboats so powerful? ›

Tug boats are also essential for non-self-propelled barges, oil platforms, log rafts, etc. Due to their solid structural engineering, tugs are small but relatively powerful machines. Their propulsion system is the main reason behind their enormous strength.

Do tugboats have bathrooms? ›

Many tug boats come with living quarters, kitchens, bathrooms, etc. for crew members to use while they're in the middle of towing projects.

What's the top speed of a tugboat? ›

How Fast Can Tugboats Move? Although it varies, when tugboats get up to speed, they can typically travel as fast as 15 knots. For a quick comparison, consider the fact that cruise ships typically move at 21-24 knots while high-speed cruise ships can travel at a rather brisk 30 knots or more.

Why do tugboats sink? ›

Tugboats may sink due to mechanical problems, collisions, and capsizing. Capsizing can be caused by mechanical failure, extreme weather, and dangerous rough seas.

Why do tugboats spray out water? ›

But the reason why these boats spray water has nothing to do with their actual function. It's known as a 'water salute' - a way for tugboats to either welcome or bid farewell to whichever large vessel is moving in or out of port.

Can a tugboat cross the ocean? ›

Marine tugboats can be divided into ocean-going tugboats and coastal tugboats, which can carry out towing and transportation operations in corresponding navigation areas, and can perform rescue tasks. Inland river tugboats mainly carry out towing operations on the river.

Can a tugboat capsize? ›

However, if the force in the towline is sufficiently powerful, it may overcome the tug's righting lever and cause it to capsize or “girt”. Girting can occur very rapidly and incidents have occurred where crewmembers have not been able to escape in time.

Why do tugboats have tires on them? ›

The role of the fendering system, in its most basic form, is to absorb the relative energy created by two vessels. That energy could be the result of a ship-assist tug pushing against a large oceangoing ship, a twin-screw tug towing a barge on the hip, or a 10,000-hp towboat pushing 40 barges up the Mississippi River.

How many hours do tugboats work? ›

Tugboat and towboat crews work varying schedules, but most crews live aboard the vessel for two to four weeks and then have one to three weeks off. In most segments of the towing industry, crewmembers stand two six-hour watches daily.

What is the pulling power of a tugboat? ›

Tugboats vary in power, with the average tugboat having a bollard pull of 400-500 kN. This is a tremendous amount of power compared to their small size, and this is primarily caused by the mighty engines used. Also, several tugboats are sometimes used to move a large vessel.

How safe is tugboat? ›

Tugboat Safety

Crews can get entangled in these winch wires, and all of the towing equipment causes a tripping hazard. The tugboat deck leaves room for slippery conditions, heavy lifting, crushing injuries, or falling overboard. All of these present an incredible risk of accident or even death.

How do tugboats pull big ships on Reddit? ›

They have enormous propellers that Swivel and a deep draft so they get a lot dig in the water. You need more than one to maneuver a big tanker. Usually they will have at least two of not three. They coordinate with the ship's captain and also use the big ships prop.

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