I get that plane tugs have huge tyres and tonnes of torque, but a boat? A tiny boat? 🤷♂️
Thanks
In: Physics
Most ships are trying to do multiple things. They want to move people/cargo, they want to go a long distance, and they want to move quickly. This means most of the ship is allotted to cargo/passenger space, and lots of food/fuel/water for the long voyage, and a pretty powerful engine so they can do 20-30 knots in relatively rough seas.
A tugboat has a single job
**Push**
It doesn’t need to go far, it doesn’t need to carry anything, it doesn’t even need to go fast, it just needs a massive engine so tugboats have a far higher percentage of internal volume dedicated to engine space.
Moving a ship in water isn’t terribly difficult, but the faster you want to go the more difficult it gets, if you just want to go fast you’ll need tens of thousands of horsepower but if you just want to go at a few knots then a few thousand horsepower will do the trick. A big propeller to efficiently get that power into the water at low speed and a tug with 3000 HP is plenty to guide a big cargo ship at just a few knots.
For a sense of power density here, a modern tugboat will have 3000-6000 HP and weigh in around 100-300 tons while a WW1 era *battleship* generally had 30,000 horsepower while weighing in around 20,000 tons, but the tugboat never really has to leave its harbor so it can be 100% focused on tuggin
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