The first sub produced in Manitowoc, the USS Peto, was completed ahead of time and under budget, and was launched into the Manitowoc River on April 30, 1942. Fitting the entirely unconventional plan, the method of launch was also unconventional. The river was too narrow to allow a normal launch, where a ship slides off a ramp lengthwise. At Manitowoc Shipbuilding Company it was necessary to launch large ships sideways off their ramp. The Navy was skeptical of the workability of this method with subs, which might heel over all the way if dumped in the water sideways from a moderate height. But models constructed showed that a sub sideways-launched would only heel over by a predicted 48 degrees, and then right itself. Still, people were anxious, and watched with anticipation as the Peto slid into the river. The result: a perfect launch and prediction, as the Peto heeled over by exactly 48 degrees. A Navy observer commented that the method of launch was "undignified, but effective."
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http://www.copperas.com/ss245/cobia.htm
