In 2016 the U.S. Navy had a marine HIMARS vehicle fire two GMLRS (GPS guided MLRS) rockets from the flight deck of a San Antonio class LPD amphibious ship. The GPS guided rockets travelled 70 kilometers and hit their target ashore. This had long been advocated by army and marine artillery officers but the navy was more interested in equipping the LPDs with cruise missiles fired from VLS cells. Each LPD of the San Antonio class was originally designed to have 16 VLS cells but that feature was eliminated (to save costs) before construction began.
Each of the twelve San Antonio class LPDs displaces 24,900 tons and is 221 meters (684 feet) long. The navy crew is 360, and 720 marines and all their equipment are carried. There is 2,500 square meters (25,000 square feet) for vehicle storage and a 24 bed hospital, with two operating rooms and the ability to set up another hundred beds in an emergency. Onboard weapons include two Bushmaster II 30mm Close In Guns and two Rolling Airframe Missile (RAM) launchers to defend against anti-ship missiles.
The ship is designed to carry and use two LCAC (Landing Craft Air Cushion vehicle), and 14 of the new AAAV (Advanced Amphibious Assault Vehicle), as well as the current AAV. Five MV-22 (Osprey tiltrotor aircraft), as well as even more helicopters, can operate off the ship's flight deck.
Each LPD 17 costs about $800 million, although the first one cost $1.4 billion. The LPD 17 class replaces four other classes of amphibious ships (LPD 4, LSD 36, LST 1179 and LKA 113). As of 2017 ten of these LPDs are in service with two more under construction. The first one entered service in 2006, about the same time the marines were receiving their first HIMARs vehicles equipped with GMLRS rockets.
When the first LPD 17 entered service without those VLS cells it was suggested that 12 ton HIMARS trucks fire GMLRS rockets from decks of amphibious ships and then go ashore once the beachhead had been established. It took ten years before the concept was actually tested and, as expected, it worked. That was because the 309 kg (680 pound) GMLRS (guided multiple launch rocket system) is a GPS guided 227mm rocket was designed to have a range of 70 kilometers and the ability to land within meters of its intended aiming point (GPS coordinates) at any range. This is possible because it uses GPS (plus a backup, unjammable, inertial guidance system) to find the target location it was programmed with. By 2012 some 2,300 GMLRS rockets had been fired in combat, with a success rate of 98 percent. GMLRS rockets cost about $100,000 each and at that point no one was using unguided MLRS rockets anymore. During World War II unguided rockets had been fired from ships offshore but these were area weapons (many rockets fired at a large area to hit whatever was there).
GMLRS made the HIMARS rocket launcher vehicle a lot more useful. Only costing about $3 million each, these smaller, truck mounted rocket launcher systems have become very popular. HIMARS carries only one, six MLRS rocket, container (instead of two in the original MLRS vehicle). But the 12 ton truck can fit into a C-130 transport (unlike the 22 ton tracked MLRS) and is much cheaper to operate. The first HIMARS entered service in 2005, about a year after GPS guided rockets did. The army successfully tested GMLRS back in 2002. Army and marine artillery officers immediately saw the possibilities.
Currently most GMLRS rockets are fitted with an 89 kg (196 pound) high explosive ("unitary") warhead. About half of that is explosives. U.S. Navy officials are talking about developing new warheads for ship launched GMLRS as well as fitting LPDs and other ships with just the GMLRS pods and fire control systems and adapting those pods to fire anti-ship and anti-aircraft missiles. But at the moment all the marines want is accurate off-shore fire support and HIMARS on the flight deck of amphibious ship could do that since 2006 and now the navy has verified that it works.