Why Warships Grow in Size​

By Dr. Steven Wills

Size does matter in describing warships, and especially the growth of particular classes of ships like aircraft carriers, destroyers, and frigates. Some defense commentators and news sources like to suggest comparisons between historical versions of a vessel type and its current size. Others will suggest that the U.S. Navy in particular desires “larger” ships because its flag officer leadership looks with contempt on small ships. Neither of these observation/accusations is accurate. Warships grow to meet capability requirements leveled on them by military leaders, civilian chief executives, and legislatures. Bigger does not always mean better, but it is often required to get all the required capability into one specific unit.

Historic examples

One of the best historical examples that explains why warships grow is the case of the Imperial Japanese Navy’s Yamato class battleships. These dreadnoughts weighed in at a staggering 64,000 tons displacement and fully-loaded were almost 72,000 tons. Its size as the world’s largest warship was not surpassed until the commissioning of the first group of U.S. Forrestal class “supercarriers” in the late 1950s and even these vessels did not equal Yamato’s light load displacement, which was exceeded only by the first nuclear carrier USS Enterprise. Yamato grew to support the tactical requirements to carry nine, 18.1 inch guns to sea, with heavy armor to deflect American 16 inch battleship guns within a given range, and operate at a speed of 27 knots. All of those requirements forced a much larger ship.

Warships also grow and change based on changes in sensor and weapons technology. A number of Second World War-gun cruisers were converted in the 1950s to carry guided missile armaments and sensors to engage aircraft and missiles. As a result, these ships grew in weight – in the case of the USS Albany, by an additional 5000 tons. Her superstructure radically changed to support air search and fire control radars as well as the corresponding electronic cooling systems. Armored gun mounts were replaced with missile launchers and magazines, necessarily having a different penetration and space below the main deck. Basic surface warship design fundamentally changed in the aftermath of the Second World War to support these new technologies at sea.

Growth in FFG-62 and DDG-X

The most recent warships accused of size growth have been the FFG-68 Constellation class frigate and the conceptual DDGX design. The new frigate design is just under 500 feet in length and will displace 7400 tons. That is substantially larger than the previous FFG-7 Oliver Hazard Perry class which was 100 feet shorter in length and displaced almost 3000 tons less than her 21^st century successor. The new destroyer class has been described as 39% larger than the preceding Arleigh Burke flight III design; estimated to displace upwards of 13,000 tons. Its length has not yet been determined, but it has already been suggested that the ship will be longer than the Burke’s to accommodate new capabilities.

Some sources immediately seized on the size of the ships to make comparisons with vessels from the familiar, yet distant Second World War. The displacement of the FFG-62 is similar to that of a World War II light cruiser while the DDGX’s displacement is comparable to a late-war U.S. heavy cruiser. These comparisons are physically accurate but miss much in terms of why the ships are larger than their immediate predecessors and why they do not appear armed to the teeth with weapons. In both classes, most of the weapons “weight” is hidden from view in vertical launch system (VLS) missile tubes fitted almost flush with the main deck of the ship. VLS tubes needed for hypersonic weapons, likely the next generation of missile weapons, are even larger than those of standard VLS cells.

The combination of a helicopter-drone flight deck and hanger where they are housed out of the weather takes up nearly 1/3 the length of many modern warships. Ships like the DDGX and FFG-62 are equipped for antisubmarine warfare as well with bow and/or variable depth and towed array sonars that require different space and more support systems than in the past. Electrical generating capacity needs have also changed warship design as additional space, and cooling is required for all of a warship’s electrical and electronic equipment, and probably soon for directed energy weapons. The space required on a ship for 32 standard VLS cells can accommodate only 12 of the larger hypersonic missile equivalents.

Numbers and sizes of guns mounted on modern warships have significantly changed from past conflicts. World War II vessels bristled with guns of all sizes, while modern warships have at best one medium caliber gun, and some close-in defense weapons in addition to their vertical launch missile batteries. Guns have not been a primary warship weapon for decades are now more for naval fire support ashore or defense against small attack craft. World War II-era gun armaments were notoriously inaccurate and even the addition of radar and action at close range did not guarantee hits. The battleship USS Washington’s famous engagement at Guadalcanal with the Japanese battleship Kirishima at very close range – under 7000 yards – and using radar-directed gunnery resulted in about 30%, + or – 5% as the ship’s wreck makes analysis difficult, of its 16 inch gun projectiles scoring a hit.

It also takes many gun hits to put a warship out of action and more to sink it. The heavy cruiser USS San Francisco survived 45 shell hits, from 14 inch to 5 inch weapons, at Guadalcanal. By contrast, modern cruise missiles do as much damage as World War II heavyweight torpedoes, like the famous Japanese “Long Lance” weapon, and in many cases one hit from a cruise missile is enough to put even larger surface warships out of action. Indeed, the large Russian cruiser Moskva was sunk by just two such weapons in April 2022.

This is not the first time that changes in size, weight, armament, and other warship characteristics have bedeviled some public observers. The same was true during the Industrial Revolution of the 19^th century when sail-powered wooden warships gave way to steam-driven successors. A 19^th century British Naval designer Sir Edward Reed explained to readers of an 1877 Op Ed in the London Times that unlike past centuries of rope, sail and muscle power, a 19^th century warship was a “steam being” where many man-powered functions were replaced by steam-powered equipment. Likewise, today’s warships are electrical and electronic platforms and the need to power and cool all of that has also served to alter warship design and cause size growth in all types of warships.

Conclusion: Growth is not Bad if the Mission Demands It

Growth in the size of destroyers and frigates has occurred since the inception of those ship types and almost always in response to change in mission, and the weapons and equipment needed to support that warfare area and tasking. Destroyers have become the standard surface combatant much as the battleship or cruiser was in the late 19^th and early 20^th century. Frigates have grown in size as well to accommodate larger and more capable rotary wing aircraft and more effective weapons such as vertical launch missile cells. The real question is not one of size growth but rather of mission. The more missions desired and greater combat efficiency will mean new gear and in many cases require more space afloat, which in terms means a bigger ship. Smaller ships can be achieved but they will support fewer missions. There is always a choice and in most cases navies choose more capabilities in order to improve combat effectiveness and survivability.

Dr. Steven Wills is the Navalist at the Center for Maritime Strategy. His research and analysis centers on U.S. Navy strategy and policy, surface warfare programs and platforms, and military history.

The views expressed in this piece are the sole opinions of the author and do not necessarily reflect those of the Center for Maritime Strategy or other institutions listed.