Your math appears off by an order of magnitude. KE = ½mv^2. [J]

Ship KE = 0.5 * (114000 short tons) * (7.5 knots)^2 = ~7.7e8 J.

747 KE = 0.5 * (510,000 lbs) * (560 mph)^2 = ~7.25e9 J.

747 avg weight = (MTOW + OEW) / 2 = ~510,000 lbs