The owners of any vessel, scow, lighter or similar floating structure lying within the limits of any harbor of the commonwealth shall not, without first obtaining a license therefor from the department, cause or permit the same to be broken up or altered to such an extent that it will not keep afloat with ordinary care, nor shall they ground any such craft within any such harbor or permit other persons so to do, or to remove any part thereof.
Mass. Gen. Laws ch. 91, § 46