Twenty years after it entered service the American amphibious ship USS Essex will spend the next two years in dry dock for over $110 million of maintenance and upgrades. This is normal and explains why you can never send all your warships off to fight at once. Depending on ship type up to a third of them will be involved in some form of refurbishment or maintenance. Over half of these ships can be sent into action anyway but with reduced capabilities and more vulnerable to battle damage.
The Essex is one of eight Wasp class amphibious assault ships. The first one entered service in 1989, and the last one (Makin Island, LHD-8) twenty years later. The Makin Island was unique in that it contained a number of technical innovations, which it did not share with other ships in the class. Built in Mississippi (and delayed by damage from hurricane Katrina) and commissioned in 2009, the Makin Island then undertook a two month voyage around the southern tip of South America to its home port in California. During that trip the navy found that the gas turbine engines saved some $2 million dollars in fuel costs, versus the steam engines in the other Wasp class ships. Because the new components in Makin Island are easier to maintain and repair, this means less time spent in port undergoing maintenance.
The 41,000 ton Makin Island looks like an aircraft carrier, and it has 21 transport helicopters, six anti-submarine helicopters, and five AV-8B vertical takeoff jet fighter-bombers (to be replaced by F-35Bs) on board. Weapons include two RAM missile launchers and two 20mm Phalanx autocannon for defense against anti-ship missiles. There are three 12.7mm and two 25mm machine-guns for protection against small boats (terrorists). The most potent weapon carried consists of 1,400 marines. The marines are landed by helicopter, while three LCAC hovercraft land vehicles. The ship is operated by 1,100 sailors. Top speed is 37 kilometers an hour and range is 17,600 kilometers.
In addition to the unique (for amphibious ships) gas turbine engine on the Makin Island, all the auxiliaries are electric, which requires fewer sailors to operate and maintain. There is an improved fire suppression system and the most advanced command and control systems available. The combination of the gas turbine engines and an Auxiliary Propulsion System are expected to result in fuel savings of over $250 million over the life of the ship.
These are the largest amphibious ships in the U.S. Navy and serve all over the world, especially near actual or potential hot spots.