within a minimum of a 3/4-inch thick aliphatic urethane elastomer shell
(see Figure B-l).
This buoy is vastly superior to the older steel formed buoy in that:
If its outer hull is punctured, it will not flood and sink.
It is considerably lighter than the steel buoy required to support a
comparable weight in the water column.
It requires minimum preventative and corrective maintenance.
Its resilient construction greatly reduces the probability of damage
caused by collision with mooring ships.
The projected operational maintenance costs are considerably less
than those of the standard steel buoy.
1.3 CHAIN AND CHAIN ACCESSORIES. Mooring chain not only secures the buoy in a
predetermined position, but its weight also serves to absorb energy caused by the
dynamic motion of moored vessels. Chain is usually manufactured in 15-fathom (90-
foot) lengths, called shots. The chain diameter required for a particular mooring
w i l l vary depending on the anticipated maximum load. Mooring chain links
normally have center crossbars, called studs, to retain the original shape of the link
and to prevent the chain from kinking when it is piled in a heap. The wire diameter
of fleet mooring chain links normally varies from 1-3/4 to 4 inches.
1.3.1 CHAIN TYPES. Chain currently manufactured consists of cast, dilok, or flash
butt-welded links. Figure B-2 contains schematic drawings of these three types of
Cast Chain. A distinctive feature of this type of chain is that the studs are
solid and cast integrally with the links. Cast chain is also made to
commercial link standard dimensions.
Dilok Chain. A dilok link, which is chiefly used in a ship's anchor chain,
and not fleet moorings, is made of two forged U-shaped pieces. A