I think most of the Severns have been re engine with he more powerful MTU's
Having lived in Cromer for many years and being a volunteer around the area, I have taken, until my move up here, the Lifeboat quarterly Magazine for some years, and the stories in the magazine of the power of lifeboats towing ships of up to 3000 tonnes out of danger is not unusual for them. Immensely strong boats.
Jim.