To become a marine engineer physical fitness is of an utmost importance. The criteria is, there should be no disease or impairment of functions of bones or joints, contracture or of deformity of chest or any joint, abnormal curvature of spine, deformity of feet like bow legs, knock knees, flat feet, deformity of upper limbs, malformation of the head, deformity from fractures or depression of the skull, deformity or uneven bending of the spinal column, fractures (healed) with a pin inside will be a disqualification.

Therefore if its a temporary fracture, it should not be a problem.

Good Luck.