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 TB 55-1900-232-10
Care should be exercised when alongside in a seaway. The motions of the tug and
tow may be sufficient to part the mooring lines, resulting in damage and causing the
tug to lose control of the tow. (Page 3-16)
Small increments of rudder angle are recommended when changing course under
tow. This will ensure that the tug maintains control of the tow and prevents the tow
from ranging up the tug. Never permit the tow to pass forward of the tug's beam, as
the tug or tow hawser may be severely damaged. (Page 3-20)
Use of vertical rollers may put tug in irons, which would seriously limit the tug's
maneuver- ability. (Page 3-22)
A hogging strap may be necessary to prevent the towline from jumping the stern
rollers when towing a high-bowed ship at short stay. A hogging strap may be
subject to excessive vertical loads. Care should be taken not to part the strap.
Failure of a hogging strap may result in the loss of tug control or ranging up by the
tow. (Page 3-23)
Running before the sea and wind can cause difficulty in steering and in keeping the
tow astern or in the desired position. The tug may be pooped or the tow may tend
to overtake the tug. The over- taking will reduce the tension in the towline and
cause an increase in the catenary which may also cause the towline to snag on the
bottom or bring the tug and tow to collision. The recommended course of action is
to head into the weather and maintain steerageway, increase hawser scope and, as
long as there is enough searoom, tolerate a negative speed over the ground. There
is no reason to slip the tow unless the towing ship is in danger of grounding. (Page
Under more strenuous sea conditions, dynamic hawser tensions, when towing down
wind, can be significantly higher than when heading into wind and seas at the same
speed and power. Turning into the wind and seas, and slowing to maintain
steerageway are appropriate under such conditions. (Page 3-27)
Do not permit the disconnect pendant or bridle to drag on the bottom, as
considerable additional resistance will result and maneuvering will be seriously
disrupted. (Page 3-30)
Approaching at too small an angle in the lee of the larger vessel is not
recommended. (Page 3-32)
Riding crews normally consist of a minimum crew and can be expected to perform
only minimal emergency functions on board. (Page 3-35)
When towing under unfavorable conditions or inclement weather and at short stay,
danger exists of being overridden. In such a situation, particular care is advised in
setting an underway material condition so that watertight doors, hatches and other
openings are secured. (Page 3-35)
The mooring loads of the tug and tow may be greater than the holding power or
strength of the tug's ground tackle. A dragging anchor or failure of the ground
tackle is possible, resulting in loss of control of the tug and tow. (Page 3-37)
Releasing the hawser under tension, or even its own weight, can be hazardous.
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