Marine Surveyors Lexicon


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Classification Of Vessels As Self-Propelled (NVIC

Subj: Classification of vessels as self-propelled

  1. Purpose. The purpsoe of this circular is to establish uniform guidelines concerning classification of certain vessels as self-propelled.

  2. Background.

    1. There is an increasing number of non-self-propelled vessels being equipped with positioning machinery, steering aids, and propulsion assist units. Heretofore, each vessel was individually evaluated with a determination being made as to whether the installed machinery was in fact propulsion machinery and, secondly, if the propulsion obtained therefrom was substantial to the extent that the vessel was required to be re-classified as self-propelled. Propulsion is one of the determining factors in the application of the various vessel inspection laws as well as certain international agreements. Propulsion also relates to the particulars of the minimum required vessel manning scales.

    2. These installations and their use can be segregated into four general categories which are:

      1. Fixed unidirectional tunnel type "thrusters" used solely as a docking aid or steering aid in restricted waters.

      2. "Kickers" used solely for the purpose of transiting locks and/or canals in which there is not room for assisting tugs.

      3. Propulsion assist machinery incorporating directional capabilities which enable the equipment to provide steering assist as well as propulsion assist.

      4. Unidirectional propulsion assist machinery providing only fore and aft propulsion capability.

  3. Discussion

    1. Any vessel equipped with mechanical means which gives it the capability of propelling itself could be arbitrarily classified as self-propelled. However, within the basic intent of the vessel inspection laws, which advocate a certain level of maritime safety, categorical classification of the described innovations as "mechanical propulsion," in some cases, would serve no useful purpose. Such classification would be appropriate only to prevent a compromise of overall safety of the vessel operation. One of the requisite characteristics of a self-propelled vessel is on board operational control and the effects of placing part or all of such control, in the form of propulsion or steering, on the towed vessel must be considered.

    2. Normally, a non-self-propelled vessel is a vessel without sufficient means for self-propulsion and is, therefore, required to be towed. Such vessels are supposedly moved by properly manned and equipped tug boats. Installation of "mechanical aids" on the towed vessel as a substitute for a tug or for a reduction of the normally required towing services, essentially places the responsibility for the safe navigation of the vessel on the proper operation of the propulsion assist equipment. Accordingly, these vessels must be adequately manned and equipped fo their proper operation.

    3. Unidirectional propulsion assist equipment normally makes a substantial contribution to the forward speed of a vessel. Therefore, applying th philosophy outlined in subparagraphs a and b, it is apparent that vessels equipped with propulsion assist machinery should be classified as self-propelled.

    4. The Coast Guard readily recognizes that vessels concurrently propelled by tugs and installed propulsion assist equipment are unique and do not logically lend themselves to a rigid application of the equipage/manning standards applicable to the conventionally powered inpected vessel. Accordingly, where feasible, such standards will necessarily require modification to accommodate a reasonable application to the various designs of this type.

  4. Action

    1. The following are guidelines which apply to those towed vessels equipped with varying types of mechanical maneuvering aids:

      1. The Coast Guard's policy in regard to unidirectional tunnel type "thrusters" is reaffirmed. Such installations will not be considered a basis for classifying a vessel as self-propelled.

      2. The Coast Guard's policy in regard to "kickers" used solely for transiting locks and/or canals is reaffirmed. Such installations will not be considered a basis for classifying a vessel as self-propelled.

      3. Vessels equipped with directional maneuvering equipment and/or substantial propulsion assist units will normally be considered as sefl-propelled vessels; notwithstanding the fact that a towing vessel may be employed in the operation.

    2. Proposals which, by reason of mode of operation or equipage, do not readily fall within the foregoing criteria shall be forwarded with complete details to the Commandant (MVI) for evaluation.

    3. For those self-propelled vessels described in subparagraph a 3, requiring inspection, complete particulars of the vessel, mode of operation and the recommendations of the OCMI shall be forwarded to the Commandant (MVI) in order that a reasonable application of appropriate inspection, equipage and manning standards may be evaluated.

C. P. Murphy
Rear Admiral, U.S. Coast Guard
Chief, Office of Merchant Marine Safety