This is mostly just thinking out loud. I make no promise of coherency or point.
I often have difficulty figuring out how to decide what features to put in a ship, or how to design a fleet, or sometimes even how to design a simpler ship design system. And I see other people here have some of the same concerns, so I thought I'd share some research I just did.
What is a battleship? You might be able to answer that, but, what is a cruiser? A heavy cruiser? A light cruiser? Armored cruiser? Strike cruiser? Battlecruiser? Frontier cruiser? Patrol cruiser?
The problem stems from many sources. There aren't any real definitions of these terms, the definitions change over time as technology or political needs change, and other reasons. What we need, though, is a firm definition of terms, which jibes as much as possible with the public's limited understanding of them.
In the years following WW1, the victorious Great Powers wanted to avoid a disastrous naval build-up, so they created the Washington Treaty and later updated it with the London Treaty. The Treaty (as I will refer to them collectively) had to set limits and some definitions, and adhering to it caused some interesting developments. Additionally, by this time technology had stabilized enough that ship designs were no longer regularly getting obsoleted before they completed construction. The result is that we have something of a definition for battleships and heavy and light cruisers.
A Capital Ship was a ship displacing more than 10,000 long tons. There were restrictions on how much tonnage ships could displace.
Cruisers were defined as being limited to 10,000 tons and their guns limited to 8 inches. Because of design philosophies, cruisers were later divided into light, which had 6 inch guns, and heavy, which had 8 inch guns. Cruisers were designed to be able to sink anything smaller than a battleship, and run from battleships. Light cruisers were actually MORE powerful than heavy cruisers of the day; the 8 inch gun couldn't do much to battleships, but they gained no improvement to performance against cruisers than 6 inch guns, because cruiser armor was only 4 inches at the time. This meant ships with the smaller guns could mount more of them, fire faster, and be even faster.
Battleships were limited to 35,000 tons and guns of no larger than 16 inches.
Armored cruisers were before this era, and were an evolution of protected cruisers, which were from when it was less common to armor ships at all, and were replaced by battlecruisers, which were larger, faster, and so much more heavily armed that they could threaten battleships or run away from them. Essentially, a battlecruiser is a battleship which trades armor for speed - as shown in its original name, battleship-cruiser - this may have been a viable concept at one point, but gunnery accuracy had progressed to the point that the battlecruiser's speed advantage never translated into armor.
The Treaty limited the number and size of Capital Ships each country could build, as well as the most powerful armament. It also limited the size of cruisers and their armament, as well as defining the difference between a light and heavy cruiser's armament.
This is not to say that the Treaty was strictly adhered to by its signatories, but the Treaty did accomplish its purpose of preventing a massive naval arms race for 10 years. Which is all beside the point.
With this long-winded way of coming about some definitions, we know how big a Capital Ship (battleship and battlecruiser) should be and a rough idea of what defines them. Same for large ships (light and heavy cruisers).
How about smaller ships, like destroyers and frigates and corvettes (oh my)?
In the WW1 era, torpedoes were the most dangerous weapon, except for their very short range. Torpedo boats were small craft designed to rapidly approach and fire them at the Capital Ships. Their speed enabled them to avoid most of the fire from their targets. To combat them, destroyers were created; these were big enough to accompany the Capital Ships across the ocean, but small enough to mount lots of small, fast-firing weapons for taking the torpedo boats out. Later they took over the job of torpedo boat, and later still served as anti-sub escorts and hunters. Destroyers needed to be only big enough to do their job and no bigger, saving on their cost so more of them could be made. The typical destroyer displaced about 1000 tons, but some countries built much larger, 2000, even 3000 in one case, without providing substantial improved armament. Modern and nearly modern destroyers have a substantially different mission and are much larger, approaching the size of a cruiser. In fact, the AEGIS destroyer and AEGIS cruiser are built on the same hull! (The displacement of a cruiser doesn't seem to have changed much in all these decades.) In further fact, destroyers have largely taken on the role of cruisers.
Frigates of old and modern frigates have little in common. As destroyers evolved into cruisers after WW2, frigates were created to take up the destroyer's old role of escort and screen, and consequently its size. Some even used the type code of DLG rather than FFG. The OHP class of frigate displaces 4000 tons, the size of an extra large WW1 destroyer. And corvettes typically weigh in around 1000-2000 tons.
I often have difficulty figuring out how to decide what features to put in a ship, or how to design a fleet, or sometimes even how to design a simpler ship design system. And I see other people here have some of the same concerns, so I thought I'd share some research I just did.
What is a battleship? You might be able to answer that, but, what is a cruiser? A heavy cruiser? A light cruiser? Armored cruiser? Strike cruiser? Battlecruiser? Frontier cruiser? Patrol cruiser?
The problem stems from many sources. There aren't any real definitions of these terms, the definitions change over time as technology or political needs change, and other reasons. What we need, though, is a firm definition of terms, which jibes as much as possible with the public's limited understanding of them.
In the years following WW1, the victorious Great Powers wanted to avoid a disastrous naval build-up, so they created the Washington Treaty and later updated it with the London Treaty. The Treaty (as I will refer to them collectively) had to set limits and some definitions, and adhering to it caused some interesting developments. Additionally, by this time technology had stabilized enough that ship designs were no longer regularly getting obsoleted before they completed construction. The result is that we have something of a definition for battleships and heavy and light cruisers.
A Capital Ship was a ship displacing more than 10,000 long tons. There were restrictions on how much tonnage ships could displace.
Cruisers were defined as being limited to 10,000 tons and their guns limited to 8 inches. Because of design philosophies, cruisers were later divided into light, which had 6 inch guns, and heavy, which had 8 inch guns. Cruisers were designed to be able to sink anything smaller than a battleship, and run from battleships. Light cruisers were actually MORE powerful than heavy cruisers of the day; the 8 inch gun couldn't do much to battleships, but they gained no improvement to performance against cruisers than 6 inch guns, because cruiser armor was only 4 inches at the time. This meant ships with the smaller guns could mount more of them, fire faster, and be even faster.
Battleships were limited to 35,000 tons and guns of no larger than 16 inches.
Armored cruisers were before this era, and were an evolution of protected cruisers, which were from when it was less common to armor ships at all, and were replaced by battlecruisers, which were larger, faster, and so much more heavily armed that they could threaten battleships or run away from them. Essentially, a battlecruiser is a battleship which trades armor for speed - as shown in its original name, battleship-cruiser - this may have been a viable concept at one point, but gunnery accuracy had progressed to the point that the battlecruiser's speed advantage never translated into armor.
The Treaty limited the number and size of Capital Ships each country could build, as well as the most powerful armament. It also limited the size of cruisers and their armament, as well as defining the difference between a light and heavy cruiser's armament.
This is not to say that the Treaty was strictly adhered to by its signatories, but the Treaty did accomplish its purpose of preventing a massive naval arms race for 10 years. Which is all beside the point.
With this long-winded way of coming about some definitions, we know how big a Capital Ship (battleship and battlecruiser) should be and a rough idea of what defines them. Same for large ships (light and heavy cruisers).
How about smaller ships, like destroyers and frigates and corvettes (oh my)?
In the WW1 era, torpedoes were the most dangerous weapon, except for their very short range. Torpedo boats were small craft designed to rapidly approach and fire them at the Capital Ships. Their speed enabled them to avoid most of the fire from their targets. To combat them, destroyers were created; these were big enough to accompany the Capital Ships across the ocean, but small enough to mount lots of small, fast-firing weapons for taking the torpedo boats out. Later they took over the job of torpedo boat, and later still served as anti-sub escorts and hunters. Destroyers needed to be only big enough to do their job and no bigger, saving on their cost so more of them could be made. The typical destroyer displaced about 1000 tons, but some countries built much larger, 2000, even 3000 in one case, without providing substantial improved armament. Modern and nearly modern destroyers have a substantially different mission and are much larger, approaching the size of a cruiser. In fact, the AEGIS destroyer and AEGIS cruiser are built on the same hull! (The displacement of a cruiser doesn't seem to have changed much in all these decades.) In further fact, destroyers have largely taken on the role of cruisers.
Frigates of old and modern frigates have little in common. As destroyers evolved into cruisers after WW2, frigates were created to take up the destroyer's old role of escort and screen, and consequently its size. Some even used the type code of DLG rather than FFG. The OHP class of frigate displaces 4000 tons, the size of an extra large WW1 destroyer. And corvettes typically weigh in around 1000-2000 tons.