Probably you don't know all the story.
The SS Manhattan was a standard tanker (even if it was the largest american ship in that period) and was selected for the 1:1 scale cruising test through the mythic North-West passage. In order to do it were necessary strong modifications of the hull. A very fine description could be found at this address
http://sunshiporg.homestead.com/manhattan.html from where I extracted the following sentences as well one the several pictures:
"To speed the conversion to a icebreaking tanker, the ship was drydocked at Sun Shipbuilding and Dry Dock Company and cut into four pieces. The 65-foot forward bow was stored at Sun, to be replaced by a new 125-foot icebreaking bow which was built in two sections. The forward piece was built by Bath Iron Works and the after piece was built by Sun Shipbuilding & Dry Dock Co. The forward section, including the No.1 cargo tank, was towed to Newport News Shipbuilding and Dry Dock Company where it was fitted with a heavy 1-1/2" thick ice belt to protect the sides of the ship from large floes of ice. The midship section, which included the bridge, was towed to Alabma Dry Dock and Shipbuilding Company where an ice belt, of steel was also fitted. The stern section remained at Sun to be strengthened internally. While the hull work was being carried on, Sun Ship workers were installing additional quaraters, laboratories and electronic gear. When the hull sections were returned, Sun rejoined them, sealed off most of the cargo tanks (which were used for ballast) and then put the ship through river trials. As completed, the Manhattan has been lengthened from 940 feet to 1,005 feet, widened by 16 feet to 148 feet, and it weight increased by 9,000 tons. "