On paper, it’s simple: Nichols Brothers builds the superstructure and Vigor Industrial builds the hull (of Washington state’s two new 144-car ferries). Nichols loads said superstructure on a barge, has it towed south from Whidbey Island to Harbor Island in Seattle (about 20 miles), where it’s slid from the barge onto the waiting hull (with engines installed).
Done and done.
The not-so-simple part was going vertical and horizontal with a structure that measures 270’x80’x46′ and weighs 1,110 tons. First you have to lift this steel assembly off the ground at Nichols’ shipyard and then push it across a county road and onto a barge sitting on the tide flats of Holmes Harbor. For this, Nichols needed a twin-track skid system that they had never used before. But unlike the infamous Empress of the North launching (the paddlewheeler ran off its tracks and into the mud), this was smooth skidding from beginning to end.
At Vigor, the hull of the new ferry, to be called Tokitae, was moved from a construction shed into a drydock that was set end-to-end with another drydock holding the barge holding the superstructure.
Tracks on the hull’s car deck were bridged across to the tracks on the barge and a diesel-hydraulic power pack inched the top across and onto the bottom.
I observed only a few feet of the last week’s transfer, but I hear that all went well and the two parts are now happily mated.
I always marvel at the ability to move massive metal like this. From modules to complete vessels, shipyards move gigantic constructions of steel all the time, but it’s always impressive and a testimony to the engineering know-how and hands-on skills of the men and women in the shipyards that do it.