Quantcast Chain Stopper.

Custom Search
TB 55-1900-232-10
If releasing the tow assembly from the tow is not feasible, then slipping the wire from the tow winch may be accomplished
by either the payout mechanism, slipping on the brake or free-spooling. If time permits, free-spooling should be avoided
and the wire slipped under the control of the payout system.
2-5.7.1 Cutting Gear. Most Naval ships are equipped with oxy-acetylene cutting equipment. Additionally, some tugs and
most salvage ships are equipped with hydraulic cutters.
Wire rope stretches far less under load than most natural and synthetic fiber lines and thus has a smaller zone
of danger to bystanders from loose ends "snapping back" in the event that it fails under high loads. The
elongation under load is sufficient, nonetheless, to be dangerous. The recoil can be extremely violent and all
personnel should stay well away from any potential recoil path.
For cutting chain, the oxy-acetylene equipment probably is the most satisfactory. For cutting wire, hydraulic cable cutters
may be better. Personnel safety is paramount in cutting any member of the tow assembly, therefore, every effort should
be made to reduce the tension. This is particularly true for cutting wire and synthetic lines. The greater the distance
between the person doing the cutting and the cutting point, the greater the safety factor. Securing the cutting torch to a
boat hook is a prudent measure. Seizing a wire hawser on both sides of the intended cut also is good practice. Cutting a
synthetic line with an ax is hazardous and should not be done under tension. The use of stoppers to control snap-back
decreases the hazards involved when cutting any chain, wire or synthetic line.
2-5.7.2 Chain Stopper. A chain stopper sometimes is employed as a quick-release device. In towing applications, the
stopper usually is connected to a deck pad by means of chain shackles. It is used to hold a towing pendant on deck
during the hookup and breaking of a tow. Stoppers are nominally rated to hold a minimum of 60 percent of the breaking
strength of the chain or wire for which they have been designed. This must be considered in their use. See Figure 2-22.
It is important not to confuse chain stoppers with pelican hooks, the latter being significantly weaker than chain stoppers
of the same nominal size, and unable to grasp the chain in the desired manner.
2-5.7.3 Carpenter Stoppers. Carpenter stoppers are used where it is necessary to develop a grip on a wire rope and to
hold it to the breaking strength of the wire. Advantages of the carpenter stopper include its quick application and release,
ability to develop full tension without damage to the wire, and low maintenance requirements. See Figure 2-26.
Old-style stoppers with smooth covers are condemned and should not be used. These old models were made
of cast metal and are subject to explosive brittle fracture upon impact. Serious injury to personnel may result
from flying fragments.
A carpenter stopper should not be used unless it is specially designed for the lay, helix, number of strands and
diameter of the specific wire rope. The stopper and wire rope should both be clean and free from sand or other
Three types of carpenter stoppers have been used in the U.S. Navy: the "old WWII style," the "improved 1948 style," and
the "modified-improved 1968 style." Only the last one listed shall be used. It can be identified by four heavy ribs on the
hinged cover and will have a Boston Naval Shipyard test date of 1968 to 1973 or be manufactured by Baldt after 1973.
2-5.7.4 Chafing Gear. Included in the category of chafing gear are materials such as mats, battens,


Privacy Statement - Copyright Information. - Contact Us

Integrated Publishing, Inc.