Quantcast APPENDIX J TUG CAPABILITIES

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TB 55-1900-232-10
APPENDIX J
TUG CAPABILITIES
This appendix is intended to assist the tow planner by addressing considerations and features of commercial ocean-going
tugs, foreign and domestic, that may be called upon for planned or emergency use by the U.S. Navy. Reasons are
provided to encourage care in the selection of commercial tugs to fulfill Navy requirements
J-1 TUG CHARACTERISTICS
This section addresses features of ocean-going tugs, with emphasis on salvage tugs. This does not suggest that other
types of tugs are not capable of safely executing assigned tasks. In fact, they usually will be more economical to hire
than a fully-equipped and fully-manned salvage tug. The salvage tug is used as the benchmark by which to compare
others, since it is the most capable and versatile type of tug.
J-l.1 SALVAGE TUG ATTRIBUTES . Salvage tugs are large, powerful and extremely seaworthy tugs They can perform
many different tasks and carry a wide variety of equipment and material, as well as a relatively large crew They have the
crew and equipment to execute a salvage task and the high power needed to refloat a stranded vessel. They are
excellent in a rescue mission, they possess excellent seaworthiness and sufficient speed to reach the casualty promptly,
the extra manpower and gear to make the tow connection under strenuous conditions, and the power to tow the casualty
to safety Finally, salvage tugs have the power, stores and fuel capacity to make them excellent for long-distance tows of
large ships and heavy objects In terms of capital cost and operating expenses, each of the three salvage tug missions-
salvage, rescue and towing- probably could be accomplished more economically and efficiently by a tug specializing in
only one of these areas. However, no other type of tug can fulfill all three missions, under all kinds of circumstances, as
well as the salvage tug
Not surprisingly, the lines separating the classes of tugs are sometimes blurred by overlapping design features, and often
by what an owner chooses to call his tug There is no universal acceptance of the salvage tug description used in the
preceding para- graph. In fact, few owners actually refer to their salvage tugs as such, preferring simply to list them as
"tugs'" Some that are called "salvage tugs" may be low-powered vessels intended for support of salvage operations,
often inshore, and would be totally unsuited for a rescue mission, long ocean tow or stranding on an unprotected shore.
The problem of identifying tugs by type is further complicated by the advent of many high-powered but very specialized
support craft involved in the offshore oil industry.  Thus, there are anchor-handling tugs, supply tugs and anchor-
handling/supply tugs. These can be useful in an emergency situation, but have minimum crew sizes, may have limited
cruising range, and usually do not carry the wide assortment of gear useful in rescue towing or salvage.
The following sections describe the attributes of salvage tugs
J-1.1.1 Length. Length is a major contributor to seaworthiness and provides for good arrangements and ample storage
for crew, stores and equipment. Length promotes efficient free-running speed. The disadvantages of incremental length
are higher construction cost and less maneuverability. Salvage tugs generally are well over 200 feet long, with the
largest approaching 300 feet.
J-1.1.2 Draft. Draft promotes seaworthiness and directional stability against off-center towing forces, and provides for
efficient propeller, design and placement. However, salvage tugs must work in shallow water around strandings, so their
drafts represent compromises. Salvage tugs generally have a draft of 16 to 18 feet, with the deepest approaching 20
feet
J-1


 


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