Page 240 - Ship Construction.DJ Eyres 6Ed

Ch20-H8070.fm Page 229 Wednesday, October 18, 2006 6:59 AM
Fore End Structure 229
involved, unless a rather convenient cylindrical form is adopted and fitted
into the bow as a single unit. This has in fact been done successfully; but in
general the protrusion forms a continuation of the side shell. Floors are
fitted at every frame space in the bulb, and a centre line wash bulkhead is
introduced when the bulb is large. Transverses are fitted at about every fifth
frame in long bulbs (see Figure 20.3). Smaller bulbs have a centre line web
but not a wash bulkhead; and in all bulbous bows horizontal diaphragm
--- ใช้เพื่อการศึกษาเท่านั้น---
plates are fitted. Shell plating covering the bulb has an increased thickness
similar to that of a radiused plate stem below the waterline. This increased
thickness should in particular cover any area likely to be damaged by the
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
anchors and chains; and in designing the bow fouling of the anchors should
be taken into consideration.

Chain Locker

A chain locker is often arranged in the position forward of the collision
bulkhead shown in Figure 20.1, below either the main deck or the second
deck. It can also be fitted in the forecastle or aft of the collision bulkhead,
in which case it must be watertight and have proper means of drainage.
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Chain locker dimensions are determined in relation to the length and size
of cable, the depth being such that the cable is easily stowed, and a direct
lead at all times is provided to the mouth of the chain pipe. Port and star-
board cables are stowed separately in the locker, and the inboard ends of
each are secured to the bottom of the centre line bulkhead or underside of
deck (see Figure 20.4). It is desirable to have an arrangement for slipping
the cable from outside the chain locker.

CONSTRUCTION OF CHAIN LOCKER The locker does not as a rule
have the same breadth as the ship, but has conventionally stiffened forward
and side bulkheads, the stiffeners being conveniently arranged outside the
locker if possible to prevent their being damaged. A false bottom may be
formed by perforated plates on bearers arranged at a height above the floor
of the locker. Where fitted this provides a mudbox which can be cleaned
and is drained by a centre line suction, the bottom plating sloping inboard.
To separate the locker into port and starboard compartments a centre line
bulkhead is fitted. This bulkhead does not extend to the crown of the
locker, but allows working space above the two compartments. Access to
the bottom of the locker is provided by means of foot holes cut in the bulkhead,
and the stiffeners fitted to this bulkhead are of the vertical flush cope bar
type. Any projections which would be damaged by the chains are thus
avoided. The upper edge of the bulkhead is similarly stiffened and may
provide a standing platform, with a short ladder leading from the hatch in the