Launching of Alabama Rehearsed for 2 Years PORTSMOUTH, VA. The battleship battle-ship Alabama will make a big splash when it is launched at the Norfolk Navy yard here next February, Feb-ruary, a splash so big that engineers already are calculating how wharves across the narrow Elizabeth Eliza-beth river can be protected frdm damage. Drag chains weighing 600 tons will help check the ship's speed. The Alabama has been "launched" time and again in miniature in the David W. Taylor model basin, operated oper-ated by the navy under the bureau of ships at Carderock, Md., and every conceivable problem connected connect-ed with the actual launching has been studied. Naval architects were letting the model of the 35,000-ton vessel slide down the ways into the basin as long as two years ago. and from these launchings engineers have collected data which tell them exactly ex-actly what to expect when the sister ship of the Massachusetts and the South Dakota actually hits the river. The model tests showed, for example, ex-ample, that a possible wave eight feet high might be set up by the battleship, but that the height of the wave in the confined waters of the Elizabeth river probably would not exceed five feet. It was found that unless the momentum mo-mentum of the ship was checked in some way the vessel undoubtedly would crash into the Berkley wharves across the river. That is why the tons of chain drags, placed in 50-ton clumps and secured to pads at the side of the ship, will be employed.