Nonwatertight (NWT) doors are used in NWT
bulkheads and are of various types. Some slide, some
fold, and others are similar to the regular house door
(but made of metal). Some NWT doors have dogs, but
fewer than those used on WT doors.
Hatches are horizontal openings for access through
decks. A hatch is set with its top surface either flush with
the deck or on a coaming (frame) raised above the deck.
Hatches don’t operate with quick-acting devices. They
must be secured with individually operated dogs or drop
bolts.
Figure 8-7 shows a typical hatch with an escape
scuttle, which is a round opening with a quick-acting
closure. An escape scuttle may also be found in the deck
(or overhead) of a compartment that otherwise has only
one means of access.
Manholes of the hinged type are miniature hatches
provided in decks for occasional access to water, fuel
tanks, and voids. Bolted manholes are sections of steel
plate that are gasketed and bolted over deck access
openings. Manholes are also found in bulkheads but are
not as common as deck manholes.
A cargo hatch and hold are shown in figure 8-8. The
hatch is a large opening in the deck that permits loading
and unloading of equipment and materials. It is covered
by hatch boards or a mechanical/hydraulic hatch cover.
A cargo hatch is protected from the weather by a canvas
tarpaulin (tarp for short). The tarp is pulled over the
hatch boards and down the sides of the coaming around
the hatch and then battened down. To batten down is to
secure the tarp by wedging battens (slats of wood or
steel) that hold it against the side of the coaming.
Superstructure
The solid part of a ship above the main deck is
called the superstructure (fig. 8-9). The masts, stacks,
and related gear above the superstructure are referred to
as the ship’s top hamper (fig. 8-10). Masts are of three
general designs—pole, tripod, and cage. On a
single-masted ship, the mast is called simply the mast.
8-6
Student Notes:
Figure 8-7.—Bolted hatch with escape scuttle.
Figure 8-8.—Cargo hatch and hold.
Figure 8-9.—Superstructure.
