Distorted ship's hull steel panels | Model Engineer
Not just ships but aircraft also, if you get up close to a USAF Boeing B52 bomber (there is one on display at Duxford) the body skin is wrinkled vertically along the full length of the aircraft. Quite normal apparently, the body skin is thin alloy to keep the weight down on such a large aircraft. The wrinkles come about from the stresses and strains of flight and is said to cause no problems in flight performance or the service longevity, the B52 has been around for donkeys years and they are still in service so the wrinkling is not detrimental.
Source: model-engineer.co.uk