In this article, we are going to talk about tugboats. Small in size, there’s a reason why some of them cost more than USD $20,000,000.
In fact, tugboats are not to be messed with. They are all muscles and strength. Maneuverability is their core. And they have indestructible winches, too.
We’ve witnessed them in port performing varieties of functions. Ship personnel often see them in action using the raw power they have.
A Quick Learning
Here, we will aid our readers, especially those taking a career at sea, to take a quick look on what tugboats do, their functions and different types around.
Ship spotters, kids of all ages and even strangers who happen to visit harbors will learn much on this post.
This is also helpful to seasoned seafarers as we uncover new tugboat designs and the careers available. We will also take a look at salary brackets for tug crews including the Master.
And for those who are planning to buy one, tugboats for sale costs around a hundred thousand to millions depending on the type. We will discuss it also here.
What are Tugboats?
When visiting a port, you might wonder how huge vessels dock deep within terminals. Its even more head scratching when you see criss-crossing traffic, narrow channels and tight bends which look impossible to pass.
Mind blowing, isn’t it?
Well, the key to all of that is with the help of tugboats.
In the simplest definition, tugboats are small boats that push, pull or tow other ships (or barges) which can not maneuver safely in their own.
Mega ships are built for cruising huge distances with plenty of sea room around. But when its time to dock in ports, their movements are constrained due to their enormous size.
Tugboats help these vessels dock safely.
How Do They Do It?
Tugboats- or tugs, are specially designed for such tasks, though there are varieties of them. The most common function of a tugboat normally seen in action is assisting other ships in port.
To get the job done, tug boats rely on the Pilot’s command who is aboard the bigger vessel.
There could be two, three, five or more tugs assisting a single ship depending on its size. The port facility, sea state and the weather are also contributing factors.
Because of their small size, tugs do not have a bird’s eye-view of the situation. They rely on the Pilot’s instruction on what to do, when to pull, how much power to give and on what direction.
Versatility and Maneuverability
Tugs are pure muscle and steel. They are built for quick response, sheer power and maneuverability. These small titans can either be tethered or not.
When secured to a vessel, they help them turn 360 degrees with ease. If the swing becomes uncontrollable, tugboats are there to stop it. Additionally, they function as a secondary rudder or as an emergency brake.
Maneuvering a vessel to berth alongside is very crucial especially when the weather is a factor. There are even instances when they helped save a vessel from colliding to a port facility.
Three Things to Get the Job Done
There are three major components that tugboats have to get the job done.
First are the engines.
Most tugs have two diesel-powered engines which run the propellers. But they are not ordinary engines. They are very powerful, enough to deliver the required power needed to perform its duties.
“A tugs power is measured in Bollard Pull (BP). When you go around a ship, you may notice that there are safe working loads (SWL) marked on bitts, chocks and fairleads.
With the help of its sensors, tugboats must not exceed their bollard pull to the SWL of the ships’ fittings. Otherwise, all hell may break loose.”
Each of their engines can power a full size locomotive. Because of their herculean strength, tugs are expected to take aim on clearly marked sweet spot of the vessel’s hull.
Their propellers also vary depending on their designs which we will tackle later.
Second is the hull shape.
Compared to other vessels, a tugboat’s hull is not designed for speed.
A huge part of it is submerged and when they power up, they sink even further. This provides more water for the propeller to thrust the tug in any direction.
The hull design is also built for maneuverability. When combined with its powerful engines, tugboats can move in any direction in matter of seconds.
Lastly, tugboats have indestructible winches.
This may sound an overstatement but I haven’t heard tug winches getting destroyed. I only saw towlines, fairleads or bitts getting mutilated by the raw power it creates while in action.
These winches do wonders especially when the lines are made fast on the bigger ship.
What Do Tugboats Do?
Tugs perform a variety of tasks, the most famous of which are the ones describe above. But they also execute other important jobs depending on their built.
From salvaging dead ships, towing huge oil platforms to pushing or pulling “dumb-barges”, tugboats can do wonders.
Well, since I mentioned it, dumb barges are barges without engines that propel themselves. That’s why they are lashed or tethered into tugboats for transport.
Categories of Tugs
Just like various ships sailing the seven seas, tugboats are also categorized based on the function they perform. Their design depends on the type of jobs they do and the environment they operate.
But all of them have the same denominator. They are nimble but very powerful. They are built to assist other vessels. And their durability enables them to handle huge amounts of loads.
Additionally, they also have strong water canons that help in fire fighting.
Also known as deep-sea tugs or ocean tugboats, seagoing tugs are built to stay longer in the open sea. They are the much bigger and more stronger type with more crew on board.
A very known type are salvage tugs which assist disabled ships or those which run aground. They are also called Rescue Tugs.
Others tow log rafts a few hundred miles to the sea. Oceangoing tugs move the largest and most valuable objects afloat like drill rigs and FPSOs.
Another category of tugboat that is very essential in every port are escort tugs. Escort tugboats provide aid to vessels navigating within the confined spaces of a port.
Since mega ships are inefficient in shallow waters and restricted terminals, escort tugs are there to provide extra “oomph”. When attached aft of a vessel, they act as emergency brakes and assist in steering.
These boats are highly maneuverable but very powerful indeed. They take on ships thousands bigger than their size and usually work in teams with other tugs.
The deployment of Escort tugs has decreased the number of accidents of ships entering or leaving port and navigating along narrow channels.
As the term implies, harbor tugs are multi-purpose tugs working within the harbor. Their size are smaller compared to the previous categories but carries many functions within the port.
Most often, they help in maneuvering vessels to its position in and out of the ports. But they are always seen towing or pushing “dumb barges”.
These barges are laden with ore, wood, containers, sand, even mobile cranes and many others. Since huge ships are not capable of sailing in inland waterways, harbor tugs deliver the goods to these areas using flatboats.
Another important role harbor tugs have is firefighting inside the port facilities.
Another category of tug which can either be escort or harbor tug are tractor tugs. The definition is varied for this one but we will sort this one out.
Tractor tugs are identified as those having their propeller units forward of the center line. They can either be Z-drives or Voith Schneider types. We will discuss these propulsion below.
Years ago, any tugboat with units aft of the center line were called “reverse tractor tugs”.
Another definition for tractor tugs is that their main duty is to supply maneuvering and or docking traction for vessels lacking that ability.
Types of Tugboat Propulsion
They all may look the same on top but below the waterline, tugboats are designed differently.
Their propulsion system evolved throughout the years as technology improved and more efficient schemes are discovered.
As we mentioned earlier, bollard pull is the measuring power of a tug’s strength. Their propulsion plays a big part.
Here are the top most common propulsion systems.
1. Conventional Propellers
As the word itself, conventional propellers are the predecessors of modern types. They are sturdy and have the simplest design.
Early tugs are made using this type. A propeller shaft which is connected to the engine on one end also has the preller on the other end which is submerged into the water.
Compared to others, they require less maintenance and is suitable for ocean going tugs.
The problem with conventional system is their maneuverability. Since the propeller is fixed, the engines must stop first and then reverse its turn in order to go astern.
There’s also a delay in its maneuvering since it uses rudders which have limited angles to turn the ship.
Hence, they are slowly being replaced by the more advance types like the Z-drives and Voith Schneider.
2. Azimuth Stern Drive Propellers
Also known as Z-drives, ASD tugs are so special that their two propellers can turn 360 degrees independently. That’s why they are called Azimuth propellers.
They are positioned side by side under the astern part of the tug. To make them more effective, each is fitted with Kort nozzles for greater thrust.
This enables faster maneuverability than conventional types as it can move in any direction. Because of this, they are built with towing winches/ hooks on the forward and aft part.
Z-Drives are very agile and can transfer to another side of the ship in a short period of time. Active seafarers have witnessed this type of tug in action.
Faster response could mean life or death especially during emergency.
3. Voith Schneider Propeller (VSP)
Voith Schneider Propeller is a specialized propulsion system which transcends the traditional designs of tugboats and most ships in general.
They are highly efficient and tugs fitted with them are able to change any direction nearly instantaneously. It can go from full ahead to full astern in a matter of three seconds.
Angle of Attack
The secret lies to its design. Unlike other propellers where they are installed in the vertical axis to direct its thrust, VPS have vertical blades that changes its “angle of attack”.
The blades are arrayed in circular fashion and revolves in a single direction. To direct the movement of the tug, the blades’ angle are changed while revolving around the plate to create thrust.
By controlling the angle of the blades, you can turn the boat on the spot. Hence called the “angle of attack”.
You can move the boat sideways (or any direction) without turning it around. This feature is very useful in tight spaces.
Careers on Tugs
Depending on the categories and size, tugboats are normally manned by four people. Some of them have a seven day on and off contract while others take on a three month basis.
Different tug types have different salary brackets just like other salaries of seafarers. Harbor and escort tugs are normally manned with 4 crews: Deckhand, Chief Engineer, Chief Mate which acts like second Captain and the Captain.
A deckhand’s salary is about $1,000 per month. Sometimes, it reaches a high of $2,400.
Chief Mate and Chief Engineer is at $4,500 and $6,000 respectively.
Meanwhile, a Captain earns at $8,000 per month.
The salary is dependent on many factors. There various seaman jobsites online to get a grasp of the available positions for various types of boats.
Tugboats: An Economic Engine
Tugboats are an indispensable part in our shipping industry. They are small in size yet their power and versatility contribute to the safety of ships going in and out of port.
These little giants are a proven component of our economic engine. Without them, huge vessels may not be able to dock safely.
What’s your tugboat experience?
May the winds be in your favor.