52-foot Motor Lifeboat
The United States Coast Guard operated four 52-foot Motor Lifeboats, also known as "special purpose craft — heavy weather", from 1956 until 2021. The 52' MLBs supplemented its fleet of 227 47-foot Motor Lifeboats.
These motor lifeboats were built in the late 1950s and early 1960s, and each displaces 32 tons.
The four vessels were all stationed within the Graveyard of the Pacific in the Pacific Northwest. The vessels are remembered for the many lives they saved over 60 years of service in brutal ocean conditions. They were withdrawn from service in 2021 and laid up due to the difficulty of maintenance; procurement started in 2024 for their planned replacements, which according to preliminary designs will be 64 feet long, overall.
Design and history
After World War II, reduced budgets meant the Coast Guard continued to use its two existing wooden 52' MLBs, which had been completed in 1935. By the late 1950s, the wooden MLBs were starting to wear out and the Coast Guard built a set of steel 52' MLBs at Curtis Bay Yard to replace them, specifically designed for the high surf conditions encountered in the area known as the Graveyard of the Pacific, off the coast of the Pacific Northwest. The steel 52' MLBs feature an aluminum superstructure and a hull divided into seven watertight compartments; because of their relatively high cost of each, only four were built. After entering service, the steering/rudder system was modified by removing the rudder guard, shortening the bilge keels, installing twin rudders, and adding a hydraulic power assist to the steering.The Coast Guard bills the 52-foot MLBs, officially designated "special purpose craft – heavy weather", as "virtually unsinkable", with self-righting and self-bailing capabilities and the ability to tow vessels as large as in seas. In comparison, the next-largest 47' MLB has a towing capacity of. To increase their endurance and capabilities, the 52' MLB is equipped with a complete galley and a fire/salvage pump with capacity.
On October 1, 2020, the fleet was placed on restricted status due to maintenance and safety concerns. By that time, the 52-ft MLBs, each more than 60 years old, relied on custom built parts to stay operational. In November 2021, all four boats were towed to Coast Guard Station Cape Disappointment and laid-up pending a decision on their future disposition. Their rescue duties were assumed by the smaller, newer 47-foot motor lifeboats.
In December 2024, the Coast Guard released a Request for Proposal for the design and production of up to six "special purpose craft – heavy weather generation II" to replace the four 52-foot MLBs, and began planning for their retirement and decommissioning due to the difficulty of maintenance.
Vessels
The 52' MLBs are the only vessels of the Coast Guard less than in length to receive names, keeping with the tradition established by their wooden predecessors.| Boat | Hull no. | Builder | Laid down | Launched | Commissioned | Homeport | Status |
| Victory | 52312 | Coast Guard Yard | Yaquina Bay | Laid up | |||
| Invincible II | 52313 | Coast Guard Yard | Grays Harbor | Laid up | |||
| Triumph II | 52314 | Coast Guard Yard | Cape Disappointment | Laid up | |||
| Intrepid | 52315 | Coast Guard Yard | Coos Bay | Laid up |
;Notes