A tugboat is a boat that is designed to push or tow other boats, barges, or log rafts which are usually much larger. Tugboats have lots of power and can go backwards or sideways almost as well as forward.
Tugboats use screw propellers which a designed for thrust. The propellers are often contained in shrouds to increase thrust and to improve their ability to change direction. The bottom of the hull slopes up which provides a good flow of water to the propellers.
The first tugboats were powered with steam engines. The engines were fairly simple, reliable, and powerful. Furthermore, wood and coal were relatively cheap and abundant. In the early 1900s, gasoline and diesel engines began to replace steam. While a steam engine required several hours for the steam boiler to make enough steam to run the engine, the internal combustion engines offered instant starting. The internal combustion engines were also smaller in size and had greater efficiency in converting fuel to energy.
There are two basic kinds of tugs today: ocean-going tugs and harbor tugs.
Coos Bay, Oregon:
Shown above is a tugboat displayed at the Boardwalk in Coos Bay, Oregon. The Koos No. 2 was the second of several tugboats to work for the Knutson Towboat Company. It was built in 1924 in the Marshfield shipyard.
Shown above is a modern tug docked at Coos Bay.
Columbia River:
Shown above are tugs on the Columbia River.
Victoria, BC: