US Coast Guard Surf Boats: Service Life Extension

Since the days of wooden hulls and human power, lifeboat crews have put to sea through dangerous surf to save the lives of their fellow seamen. The first engine-powered boats allowed decks and cabins that afforded a greater level of safety. When the US Coast Guard developed their 47-foot surf boat in the late 1990s, it set a whole new standard for lifeboats.

Designated 47-foot MLBs, these all-aluminum craft demonstrated spectacular performance. Capable of handling 60-knots winds, 20-foot breaking surf, and impacts up to three Gs, the boats carry four crew and up to 30 passengers.

The ultimate expression of the 47 MLB’s indominable nature is its ability to self-right itself if overturned. Not only will the boat turn right side up, it will do so with both main engines running and ready to drive the boat ahead. This was a tall order for any engine that would hope to qualify for the repower and upgrade. Cummins met that challenge. After extensive testing, a pair of US-built, 6-cylinder, Cummins QSC8.3-M engines were chosen for the repower. These EPA3-rated engines have four valves per cylinder and produce 530 BHP each at 2600 RPM. They replace the original 435-hp, Detroit 6V92TA mains. The new engines exceed the contracted requirements in terms of noise reduction and fuel economy.

In the summer of 2020, Birdon America delivered the first of the upgraded 47 MLBs which was accepted by the US Coast Guard. It had passed or exceeded all the US Coast Guard requirements under the contract. Birdon will now proceed with the service life extension of over 100 of these vessels built between 1997 and 2003. Work on the first boat was completed at the All-American Marine yard in Bellingham, Washington. Other west coast boats will follow. The 47 MLBs on the east coast will be upgraded at an east coast yard beginning in 2022.

Photos courtesy of Birdon