The four new boats will be the largest submarines ever built for the Royal Navy—displacing 17,200 tons with a length of about 502ft—but they will only have 12 missile tubes rather than the 16 found onboard the current Vanguard-class. The new boomers will also share technology with their U.S. Navy counterparts—the Columbia-class Ohio Replacement Program SSBNs—using a common missile compartment (CMC) design. Once completed, the new boomers will enter service in the 2030s.
the 17,200-ton boats will be larger than their 15,900-ton Vanguard-class predecessors, the new SSBNs will carry four fewer missiles. Part of the reason for the vessels’ larger size is likely due to the need for enhanced stealth—larger submarines are inherently quieter. But it is also possible that the British have adopted an all-electric permanent magnet motor to drive the boat—similar to what is planned for the Columbia-class—for their new SSBNs, which might also account for the increased displacement.
The British submarines’ PWR-3 pressurized water reactor plant is thought to draw heavily upon the technology used on the U.S. Navy’s General Electric S9G reactor plant found onboard the Virginia-class attack submarines. However, the Columbia-class will have a newer 42-year life-of-the-boat reactor that is significantly more powerful than the S9G.
The Successors are already going to be sharing their CMC (Common Missile Compartment) modules with their Columbia-class counterparts
SOURCES- Royal Navy, National Interest