Recently I was thinking about how in the first Pirates of the Caribbean movie The Black Pearl was claimed to be the fastest ship ever and the HMS Intercepter was the fastest ship in the royal navy, and in one scene The Black Pearl is easily catching up to the Interceptor. I understand that these are fictional vessels, but I still didn’t understand how one could be considerably faster than the other, when I can’t really tell the difference between the two designs(to the untrained eye, you wouldn’t be able to tell which one is faster by looking at it.) How is one ship so much faster than another ship that appears to be designed very similarly?
(Edit: thanks, i have a bit better understanding of what can cause this, thank you to everyone who has commented, although feel free to elaborate or provide additional explanations if you wish!)
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A combination of how heavy the ship is and how efficiently her sails can capture the wind. Lighter ships move faster because it takes less energy to move them. Better sail setups can convert more energy from the wind into forward momentum. Everything beyond that is just a matter of balancing the two out.
There’s an interesting characteristic of boats called the _hull speed_.
As a boat moves through the water, its bow creates a wave. The faster the boat goes, the longer the wavelength of the bow wave gets. At some speed, the wavelength of the bow wave is equal to the length of the boat itself. The boat is effectively stuck in the trough between two wave crests. The speed at which this happens is the bow speed.
For a lot of boats, that’s a limiting factor. The amount of energy needed to go faster goes way up, because the boat has to climb out of that trough that it’s stuck in.
If the boat has a lot of surplus power, like big engines or lots of sails and plenty of wind, it can climb out of the trough and start planing. You may have seen this with motorboats, where the front part of the boat isn’t even in the water.
The TL;DRBI5 is that a long boat can go faster than a short boat, and a boat with more power (like more sails) can go faster than a boat with less power.
The simplest answer is that some ships are just built to be faster than others. Fast ships have hulls that cut through the water better and tend to be long and narrow, but they can’t hold as much stuff (crew, cargo, cannons, etc.). Also, fast ships tend to have lots of big sails; the bigger the sails, the more wind they can catch to push the ship along. To have lots of sails, you need taller masts, or wider arms, or more masts, or a combination of all three. Weight, drag (how much the shape of the ship pushes against the water), and total sail area all contribute to speed. There are lots of more complicated factors that go into sailing ship speed, but that’s the ELI5 of it.
Others have good answers, but in addition… even two ships built with the same hull shape and sail area can have very different top speeds. As you can see on any pier, barnacles eventually cling to just about everything in sea water. They create drag and seriously slow the ship. If a ship was generally only capable of 15 knots max but barnacles have slowed it to 12 kts, that’s a big difference if you’re running from pirates.
Ship builders used various materials to lessen how quickly fouling occurred but all ships eventually had to be taken out on the beach and have their bottom scraped.
Since you already got explanations for non-fictional ships, I’ll explain why the Black Pearl was faster. It was formerly the Wicked Wench, with Jack as captain working under the East India Trading Company. But it was set on fire and sunk by Cutler Beckett after Jack refused to deliver a “cargo” of slaves. Jack then made a deal with Davy Jones to have the Wench raised from the depths. And so it was, with a permanently charred hull, and became the Black Pearl. It was a deal with the devil, so-to-speak, and the ship itself has supernatural properties, making it faster than other ships.
Consider cars briefly. A lighter weight car requires much less power to accelerate. Air acts as a liquid (sort of) at higher speeds so more aerodynamic designs make cars slice through the air easier.
If a boat has more sails, larger sails, better designed sails, better placed sails, then it will catch more air and accelerate more quickly. If the boat hull (the part in the water) is designed to be more hydrodynamic, it’ll slice through the water much easier. If the boat is as light weight as possible, it will require much less air to accelerate compared to a larger boat.
No one has mentioned the skill of the sailing master. Setting, trimming and balancing sails to the wind and tack is a subtle art. Notice how there are winners and losers in single class sailing races, where each boat is identical.
Just so that it has been said:
Sails do not just get “pushed” by the wind. Sails are airfoils, similar to a vertically mounted airplane wing. When the direction of the wind is moving at an angle across the sail (instead of directly at the face of it), there is also a force generated on the sail perpendicular to the direction of the wind. It is the combination of these two forces which propel a sailing vessel forward.
Manipulating the angle of your boat and/or sails relative to the wind is how a sailing vessel can sail into the wind (although not directly into the wind). Some vessels can even sail faster than the wind speed by carefully combining the two sail forces.
https://en.m.wikipedia.org/wiki/Forces_on_sails
In simpler terms than the hull-speed as mentioned, there are a number of factors:
Number of sails carried: More sails mean more wind is utilized.
Sail design: Square sails aren’t necesarily the best (though technically with the wind directly behind you they are). A ship/boat with a certain mix of sail types can go “faster” in different situations
Condition: Is your ship being cleaned regularly? That matters
Weight: How heavy is said ship which will increase the mass/drag and slow the ship?
Rigging: Spart of a ship’s “speed” is it’s ability to turn to take advantage of winds, namely in tacking. A ship that can turn tighter and faster is then technically “faster” because it’s cutting out unnecesary travel distance More effecoemt riggings that allow for faster sail adjustment aids in this.
And of course the shape of the hull: Ships were always trying out different ways to cut the water. Some were better than others.
a lot of people already gave some good answers but i’ll try to ELI5 it more.
Let’s say you have one kind of engine. doesn’t matter what it is but you can throw it in multiple vehicles.
You throw it in a normal sized sedan and it can go 60mph easily. You throw it in to a motorhome and it can’t go faster than 30 mph.
Some ships are just larger and full of more stuff. Usually thicker wood for defense, more cannons for attack, and more men for those cannons and for fighting, and more food and supplies for those men and cannons.
It is almost like the rocket equation problem. each cannon is heavy, then each cannon needs dudes that need food… and it also needs ammunition and gunpowder.
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