What do Tugboats Actually do?

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  • Written By: Bronwyn Harris
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Tugboats have inspired many hardworking cartoon and storybook characters throughout the years. Real-life tugboats are as tenacious and full of character as their cartoon counterparts, and tugboat crews are often the salty sailors of legend. These stout little boats range from the 50 foot harbor or yard tug to the 250 foot long off-shore anchor harboring tugs. Tugboats generally perform one of three tasks. The first is known to those in the industry as a "ship assist," as in assisting larger ships in and out of harbors and ports. Tugboats also tow ships and barges which are not under their own power, and aid in construction work taking place on or near a body of water.

Today's ships are vastly larger than they have ever been throughout history. These huge ships can move forward and backward easily, but are usually unable to maneuver sideways. Some ships, have transverse bow thrusters which can assist the ship to move sideways, but even these advanced designs only allow limited side to side mobility, and many ships still require what is known as a "tug assist."


In a tug assist, one or two tugboats meet the larger ship while it is still outside the port. A common scenario has one tugboat behind the ship, attached to it by a line. This tugboat acts as a brake to slow down and stop the large ship. Another tugboat can be near the bow of the ship, at the port or starboard side, depending on which side the captain of the assisted ship wants to moor. This second tugboat is attached to the side of the ship by a line, allowing the tug to push or pull the boat in the desired direction.

Tugboats are also used for towing. They can move a floating object with no power of its own, such as a barge, or a "dead ship," a ship that is not under its own power and is moved from one location to another. A typical towing situation would involve one tugboat with a towing cable attached from the stern of the tug to the barge or dead ship. A tandem tow is when one tugboat is towing two barges in a line. Barges can be used to move almost anything that a ship can, and the tugboats move them from one place to another.

A tugboat's role in a construction project is more varied and complex. Typically, a tug assists in construction by moving small barges carrying the construction equipment from place to place on a construction site. The tugboat can also act as a crew boat so that the construction crew can get around at crew change time.

Whatever their tasks, tugboats are essential to the marine industry. These workhorses of the sea can move vessels hundreds, even thousands, of times their own size. These tenacious little boats offer a perfect example of why it is always best not to judge a book by its cover, or in this case, a boat by its size.


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Post 24

Does a tug have to be in any particular condition when requested to provide towing services?

Post 23

I am working at Seaports Fire and Safety department, and I want to know how many fire pumps should a tugboat have, as required according to IMO fire safety regulations.

Post 22

Is it true that smaller tugs with about 10 Tons Bollard Pull need to declutch their engines if they are fire fighting or use one engine for manoeuvering and one to drive the fire fighting pump?

Post 21

I heard a ship's pilot signals the tugboats by horn signals. Are the pilot's signals different from those of the tugboats, and could you tell their meaning? Also, are there different systems of signals for tugboats on rivers, vs. in harbors, vs. at sea? (Used to hear them on Lake Michigan, and in San Francisco Bay, but read of tugs docking huge liners in NYC. Fascinating!)

Post 20

I was recently told that when a tug pulls a barge with a cable, the weight of the cable is actually doing most of the work. Can you explain this?

Post 19

I work on an ocean going tug as a Chief Engineer. I also hold an AB unlimited as well as a Tankeman PIC.

To answer some of the questions here. Yes, we go to sea, and also stay in the harbor. My particular vessel does it all, but there are tugs that specialize. It depends on the design.

Barges can go to sea but like everything else, some are better suited than others. Tugs cross the ocean all the time, the larger tug, the better the ride.

Most US tugs stay within 200 miles of the coast, as most wheelhouse people's licenses are limited to this range, but there are some that go further.

Pushing a barge is more efficient

and faster, but only certain boats can push offshore. We also put them on the hip (on our sides) for in close handling. My tug is 98 feet, 4200 hp and we tow offshore but push everywhere else.

The reason we make huge wakes is we are displacing a lot of water. My tug draws about a 5-6 foot wake when moving at full speed 12-14 knots light boat, 10-12 knots pushing a barge. We have a 14 foot draft. That's the boat under the water.

As an engineer, I spend most of my day below the water line. Anything going in and out the Columbia river can handle the swells as this river's bar is notorious for being nasty. Nothing comes to the shores of America without a tug involved somehow. We also deliver fuel to the ships by barge, called bunkering.

Post 18

I live on the mouth of the Columbia River and we see tugs and barges going back and forth all day. I've been curious as to whether tugs actually go 'out to sea.' Do they just follow shore routes? Or can they actually cross an ocean? Is one really any less dangerous than the other? Most of the barges I see don't look like they could handle swells of any significant size.

Post 17

Is it easier for a tugboat to push a barge or pull a barge?

Post 16

I grew up in the Virginia Tidewater, and remember how fun it was to go through the wake of a tugboat. Our boat would dip down really deep into the trough of the wake. What makes tugboat wakes so unique?

Post 15

The water shooting out of tug boats is from their fire fighting cannons. Tugs will often test their fire fighting equipement during safety drills or for exhibition purposes. 1 short horn = I am turning to port 2 short horns = I am turning to starboard 3 short horns = I am putting my engines astern 5 short horns = I do not understand your intentions

Post 12

"Why do tugboats shoot water out?"

I think you might be referring to the "sea" water circulation system which is used to cool the engine's "fresh" cooling water by means of the heat exchanger.

The heat exchanger is basically a radiator with separate sets of piping in which sea water and fresh engine water circulate, thereby cooling the fresh water which cools the engine.

The water shooting out of ports on the hull is attributed to the powerful sea water circulation pumps needed to cool the the large engines found on tugboats.

Post 10

Why do tugboats shoot water out?

Post 9

Can tugboats push and pull boats? Do they help large boats to stop?

Post 7

This is the resident mariner once again. The answer to your question is in two parts. The first part is to do with the shape of the boat's hull. Sea-going tugs tend to be longer and to have a higher bow than harbor or river boats. This lets them cut through the waves rather than having the waves crash over the decks. The hull of a sea-going tug is either round or “V” shaped on the bottom. This hull shape is more stable, and gives a more comfortable ride in bad weather. Many river boats have flat bottoms which would make for a very uncomfortable ride in bad weather.

The second part of the answer is the way the

crew prepares their boat and themselves for the trip. Nothing is left laying around where it could go “adrift.” Every hatch is dogged, or locked down, and every bit of gear and stores are stowed safely away where they can not come loose and become a safety hazard in rough seas. Furniture is bolted to the decks and bulkheads so it cannot slide or topple in rough seas and the crew themselves are always alert, even on their off time, to changes in the sea and in the boat. They are prepared to fight a fire, dewater a flooding boat, and or abandon ship at a moments notice the whole time they are at sea.

River and harbor boats have an easier time of it because they rarely face the swell of the open ocean and if they are on fire or are sinking they have a good chance of finding a safe place to run the boat aground and get off.

Post 6

As it happens, the author's information is based on an interview with a tug crewman (I think he's officially an able-bodied seaman), the same fellow who identifies himself above as the resident mariner. I'll see if I can get him to weigh in on this new question!

Post 5

MNP wants to know how an ocean going tug is different from a harbor tug besides size?

Did the author interview any tug crewmen when researching this article?

Post 3

This is the resident mariner. Also, when you pass another vessel on a river, you can use your whistle to indicate on which side you would like to pass. One whistle means passing on the port side, and two whistles means passing on the starboard side.

Post 2

You're right! Our resident mariner says that one long whistle means the ship is leaving, and six or more short blasts followed by one long one is a signal to abandon ship. Good thing you never hear more than five!

Post 1

I live next to a river and I know that the numbers of whistles mean something. I know that there are never more than 5 and I wonder what each number of whistles means.

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