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 TB 55-1900-232-10
3-3.3 AT ANCHOR
a. Tug underway/tow anchored. In moderate seas, the tug should come alongside the anchored tow and tie up with the
tug's stern as close as possible to the bow of the tow. The tow then passes a line to the tug, which is used to pull a
messenger and then a portion of the tow's chain pendant to the tug As the chain comes down on the tug's fantail, a
stopper is passed on it to restrain it while the tug's crew rigs the remaining towline connection. When the connection is
made, the chain stopper is released and the tug maneuvers clear. Assistance of a harbor tug usually is required. When
headed fair, the tow weighs anchor. With the anchor housed on the ship, the tug can start ahead, slowly accelerating.
Significant time is required to attain the desired catenary in the tow hawser and come up to towing speed. If the tow has
no power to its anchor windlass, the crew should rig an appropriate retrieval line and buoy so that the anchor can be
slipped and recovered later. If unfavorable conditions for going alongside prevail, passing the hawser can be difficult.
The tow remains anchored as the tug approaches and maneuvers to receive the messenger. Expert seamanship is
required to prevent the tug from drifting out of range on the downwind approach
b. Tug anchored/tow anchored. Rather than passing the towline while underway, often it is advantageous for the tug to
anchor upwind/upcurrent from a large ship. While at anchor, the tug can prepare the towline for passing. The tug veers
her anchor chain until within a short distance of the tow's bow. When the tug's stern is close aboard the tow's bow, the
towline can be passed and the connection made. With the towline connected, the tug can use her engines to come
ahead and weigh her anchor, veering towline as necessary. With the tug free to navigate, the tow weighs her anchor and
the tow commences. If the tow does not have power, it may be necessary to slip the chain and anchor. A buoy should
be used to mark the anchor's position so that the anchor and chain can be recovered later.
c Tug anchored/tow underway with steering tug(s). The tug anchors and settles out into the wind and current. The
steering tug(s) brings the tow up to the stern into the current or wind. A pendant or lead chain is passed to the stern of
the tug. Using the tug's stern capstan, the messenger is heaved on board until a sufficient amount of chain is brought on
board to pass a chain stopper. The connection is made, the chain stopper released and wire paid out as appropriate.
The tug weighs anchor and commences accelerating at a very slow rate of speed. This method is safe, simple and
expeditious.
3-3.4 ACCELERATION. In all these instances, when getting underway, build up speed slowly. Judicious acceleration and
deceleration prevent damage to the towing gear. The preferred means of controlling strain when commencing varies
with the class of towing ship.
Frequently the tow will commence in restricted waters or a narrow channel. Beam winds and/or waves may tend to force
the tow out of its channel or into the path of other ship traffic. Even with operable steering machinery, the initial towing
speed will be insufficient for controlling the tow. For these reasons, it is prudent to retain harbor tugs alongside the tow,
or immediately available, until the towing ship's Commanding Officer is satisfied that he can control the tow within all
existing navigational constraints.
As speed increases, the resistance of the tow will increase. Yet water depth may not permit sufficient hawser payout to
establish a catenary. The towing machine's automatic features are especially useful in this situation.
SECTION IV.
3-4 TOW AT SEA
3-4.1 SETTING COURSE. When adequate sea room is achieved, maneuver to set course and begin streaming the tow.
Do not stream to
3-18
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