Fleet Moorings

As discussed in Section 3.5.3, fleet moorings are subject to several causes of deterioration. The methods of repair and maintenance of deteriorated fleet moorings can be classified into three general areas:

in-place repair, total replacement, and ca-thodic protection.

5.4.1 In-Place Repair

In-place repair of fleet moorings may consist of repair of the buoy's protective coating, fender system, or buoyancy chambers or partial replacement of mooring chain components. Repair of the buoy's protective coating is required from time to time because of abrasion or impact damage. It is necessary to first clean the exposed steel, as described in Section 2.12.2, as well as the coating surrounding the steel. An ep-oxy-polyamide protective underwater coating, such as those described in Section 2.12, is then spread by hand over the cleaned exposed steel and at least 1/2 inch over the surrounding cleaned coating.

Mooring buoy fender systems, especially those made of wood, require periodic re placement. Replacement rubber fenders of Type R, Class RS, Grade 72S (A,B,D) rubber composition are recommended for use. Buoys that are 9 feet 6 inches in diameter and larger require D-shaped rubber fenders that are 8 by 8 inches in cross section, while 6- by 6-inch fenders are used for smaller buoys. Rubber fenders are usually fabricated in eight preformed sections to fit the circumference of the buoy.

Buoys may suffer from buoyancy loss because of a crack or hole in their structure. Some of the lost buoyancy may be recovered by installing packets of foamed plastic inside the buoyancy compartments. Polystyrene foam, such as Styrofoam, is relatively inexpensive to purchase in quantity and can be cut to any desired shape. Syntactic foams produced by bonding hollow glass or plastic balloons together in an epoxy resin are highly resistant to water penetration and are quite suitable for use.

Continuous metal spiral

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Outerwrap interlocked steel carcass

External plastic sheath

Crosswound tensile armors

Intermediate plastic sheath

Flat steel spiral

Zeta spiral Inner plastic tube J

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