the same and, from this point, will be referred to as
when used as a wharf. it becomes a quay. or marginal
8-5. Piers are structures constructed perpendicular or
SEAWALL--A wall along the shore to prevent
approximately perpendicular to the shoreline which
encroachment (enter by gradual steps) by the sea. But if
provide berths and slips to tie up, or moor, vessels on
the wall is used as a wharf, it is not called a seawall.
SLIP-The area between two piers.
8-6 Bulkheads and retaining walls are structures
8-9. Wharves and piers are constructed from timber.
constructed approximately parallel to the shore to protect
concrete, steel, or a combination of these materials.
the shore from soil erosion.
Usually, timber is the most widely used, because it is
8-7. Wharves and pier must be maintained to the
more economical, lighter, and easier to work. However,
extent necessary to insure safe and efficient use for
the serviceable life of timber is shorter than the others,
berthing, servicing, repairing, and overhauling seagoing
because it is subject to decay by fungi action and
The principal jobs of maintaining these
structures are as follows:
a. Replacement of broken or damaged fender piles.
most part, creosote treatments are very effective against
b. Replacement of deteriorated wood decks and
stringers and other timbers affected by attacks of
8-10. Before any waterfront structure is constructed,
there are many factors to be considered. Among these
c. Replacement of corroded and deteriorated pipe.
d. Removing scale and repainting steel member.
a. The sizes of vessels to be accommodated.
e. Repairs to pavement deck surfacing.
b. The amount of cargo to be handled.
c. The loads (dead and live) to be carried on the
8-8. There are several terms specifically applicable to
d. The depth of the water.
the maintenance and repair of waterfront structures and
e. The variations in tide.
Some of these terms and their
definitions are as follows:
BITT--A double post to which vessels are moored, or
8-11. Construction Features. To make sure that our
wharf or pier can absorb the abuse, we must use the type
BOLLARD--A single post to which vessels are moored,
of construction components recommended.
8-12. Pilings. There are three types of piles used for
CHOCK--A block with two horn-shaped converging
wharf and pier construction: bearing pile, fender pile, and
arms used t guide lines. It is sometimes called a fairlead.
mooring pile. If timber is used as piling, it must be
A chock is also considered a horizontal timber fitted
between two vertical fender or fender piles.
compound to protect it from fungi and marine borer
CLEAT--A horizontal device with two diverging arms
to which mooring lines from vessels are fastened.
8-13. Bearing piles support the wharf or pier
DOCKS--Sheltered basins in which vessels are berthed
framework and decking. The piles should be straight and
measure at least 6 inches across the top, 18 inches across
DOLPHIN--Usually a cluster of piles placed in the
the butt (bottom), and from 60 to 80 feet in length. The
water for mooring vessels or keeping them away from
length varies according to the depth of the water and
structures, shoals, or shores.
condition of the bottom. These bearing pies should be
FENDER--A structural feature used to lessen the shock
spaced from 6 to 10 feet apart, center to center, in one
or minimize the damage when vessels come in contact
direction and 5 feet apart, center to center, in the other
with shore structures.
MOORING--Facilities to which vessels are safely
8-14. The force of a moving ship (coming in direct
secured. They include mooring platforms or islands,
contact with bearing piles) is sufficient to collapse a
dolphins, piers, wharves, etc.
wharf it the pilings are not protected. To furnish this
PIERHEAD LINE--An established harbor line marking
protection and to absorb the initial shock, fender piles are
the permissible limit of pier construction. This is usually
placed approximately 2 1/4 feet out from the centerline of
limited to open type construction.
the outside row of bearing piles. These piles are placed
QUAY WALL--A wall along the shore to retain the
approximately 18 feet apart and along the sides where the
soil. It may be used as a wharf: however.