This is the starboard propeller of the Canadian coastguard [sic - Coast Guard] Icebreaker, John A. MacDonald [sic - Macdonald]. The propeller was damaged while the John A. MacDonald was assisting the 115,000 ton oil tanker, SS Manhattan, in her historic crossing of the Northwest Passage in 1969.
On many occasions during the voyage the John A. MacDonald under the command of Captain Paul Fournier freed the Manhattan from ice holding her fast.
For days both vessels battled ridges of ice 12 to 15 feet thick. On September 14th, while entering Prince of Wales Strait at 0730 hours, the John A. MacDonald noted vibration from her starboard shaft. She continued escort duties until both vessels entered open water at 1700 hours.
On the return of the John A. MacDonald to the Darthmouth coastguard base, it was revealed in dry-dock that the pressure of ice had broken off two propeller blades, as shown here.