Friday, August 05, 2016

21 electric motors and controllers powering the winches that righted the capsized USS Oklahoma after the attack on Pearl Harbor, were salvaged from Honolulu's retired streetcars.

By late July of 1942 the Navy had created a plan to salvage the USS Oklahoma commencing in March 1943. This was a cooperative effort between the Navy and Pacific Bridge Company, a commercial construction and salvage operator. The initial stage in salvage required righting the capsized ship.

This was accomplished by lightening Oklahoma by removing 350,000 gallons of fuel oil, and filling the empty bunkers with air. Next twenty one electric street car motors were installed on Ford Island and connected by cables to the hull of the ship. The street cars had been less used into the late 1930s as cars became more popular, and by the summer of 1941 were pulled from service completely, having been replaced in the Rapid Transport Company with busses and trolley coaches.

Twenty-one concrete foundations were poured near the water’s edge on Ford Island. Seated in them were the electric motors from the Honolulu street cars powering winches. With a system of hauling blocks and pulleys, the winches’ combined strength could exert a titanic 345,000 tons of pulling force. Forty-two miles of one-inch wire ran from the winches, through the blocks, out over a row of 40-foot A-frame towers built on Oklahoma’s hull, and finally to pads welded to the ship.

Finally, twenty-two hundred tons of crushed coral was dumped on the shore side of the ship to prevent sliding.

 During 1942, the Navy made arrangements with the Pacific Bridge Company, a firm of skilled engineers who were playing an indispensable role in Pearl Harbor salvage work, for a joint project to raise Oklahoma.

Lugs were welded to Oklahoma’s upturned hull. Cables were attached to these, and passed over the tops of high wooden towers erected on the hull, called bents, to give the cables better leverage, then hooked to powerful electric winches on Ford Island.

Weights that could be reached were removed, oil was pumped out of accessible tanks and compressed air was used to create an air bubble to lighten the hull. When all was ready, the winches took a careful strain on the righting cables, and Oklahoma gradually edged back toward an even keel. This began March 8, 1943. Turning at a snail’s pace, the winches reeled in cable for more than three months.  By June 16, Oklahoma was upright.

Once she was upright, great efforts were made to cover the many holes caused by Japanese torpedoes. This was accomplished by securing patches, one of which was 130 feet long by 57 feet tall. Large portions of the ship were then dewatered with the use of ten inch water pumps. The ship was finally floated in early November 1943 and moved by tugs into Drydock #2 some weeks later.

Righting such a huge capsized vessel with ashore machinery was a tremendous engineering feat, not repeated again until the recovery of the cruise ship Costa Concordia in 2014.

When the Railroad Leaves Town: American Communities in the Age of Rail Line Abandonment--Western U.S.Sep 1, 2004 by Joseph P. Schwieterman  Salvage of the Oklahoma at Pearl Harbor, Lee P Morris, November 1947 Engineering and Science Monthly

I bet you didn't expect a Pearl Harbor naval salvage post today. .. but street car motors! Seriously, that is a surprise.


  1. Pretty interesting. Thanks.

    1. You're welcome! It's quite far off my normal type of posts, but... I dig history, was stationed at Pearl, and was surprised about the street car connection. Heck, I started out just reading about how the trains were once common in Honolulu, and then I ran across what they did with the motors... far out is an understatement

  2. Awesome post! I knew they used the shore-based winches t right her, but I never knew about the streetcar connection.

    1. thanks! I'm sorta happy with it myself!