[1][2][3] The boats were not equipped with an anti-capsizing feature; Triumph sank after a large wave struck her during a rescue operation at the mouth of the Columbia River on January 12, 1961.

Four steel-hulled 52-foot Motor Lifeboats were designed with self-righting buoyancy chambers and completed between 1956 and 1961 to replace the older wooden-hulled MLBs.

[2] They were designed to operate in extreme sea conditions, complementing the Coast Guard's smaller 36 foot motor lifeboats, which had a shorter range and lacked onboard facilities for sleeping and meal preparation.

[2] On January 28, 1960, the Invincible's engine stalled after she rolled 90–100° to port while transiting the Grays Harbor Bar and she was taken in tow by the fishing vessel Barbara Lee; the Barbara Lee subsequently capsized after being struck by a sneaker wave, and a 36-foot motor lifeboat was dispatched to hold Invincible until she could be towed to safety by USCGC McLane.

[2] Modern motor lifeboats are designed to be self-righting by incorporating buoyancy chambers within the hull which rapidly force the boats right-side-up if they overturn.

[9] After passing the tow to Triumph, the 40' UTB was crossing the bar when a large wave caused CG-40564 to founder, and the 36' MLB also was swamped by large waves, but the 36' MLB re-righted and, after rescuing the crew of CG-40564, radioed Point Adams and proceeded 7 mi (11 km) west to the lightship Columbia[9] and put the survivors on the lightship safely.