Page 191 - Ship Construction.DJ Eyres 6Ed

Ch17-H8070.fm Page 180 Wednesday, October 18, 2006 6:57 AM
180 Ship Construction
forces is dealt with in Chapter 16. Panting which is discussed in Chapter 8
will also influence the requirements for the scantlings and strengthening
of the shell forward and to a lesser extent at the aft end. Where a ship is to
navigate in ice a special classification may be assigned depending on the
type and severity of ice encountered (see Chapter 4) and this will involve
strengthening the shell forward and in the waterline region.

--- ใช้เพื่อการศึกษาเท่านั้น---
ADDITIONAL STIFFENING FOR PANTING Additional stiffening is
provided in the fore peak structure, the transverse side framing being
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
supported by any, or a combination of the following arrangements:

(a) Side stringers spaced vertically about 2m apart and supported by struts
or beams fitted at alternate frames. These ‘panting beams’ are con-
nected to the frames by brackets and if long may be supported at the
ships centre line by a partial wash bulkhead. Intermediate frames are
bracketed to the stringer (see Figure 17.4).
(b) Side stringers spaced vertically about 2 m apart and supported by
web frames.
(c) Perforated flats spaced not more than 2.5m apart. The area of perfora-
ึ
tions being not less than 10 per cent of the total area of the flat.

Aft of the forepeak in the lower hold or deep tank spaces panting
stringers are fitted in line with each stringer or perforated flat in the fore
peak extending back over 15 per cent of the ship length from forward.
These stringers may be omitted if the shell plating thickness is increased
by 15 per cent for vessels of 150 m length or less decreasing linearly to
5 per cent increase for vessels of 215 m length or more. However, where
the unsupported length of the main frames exceeds 9 m panting stringers
in line with alternate stringers or flats in the fore peak are to be fitted over
20 per cent of the ships length from forward whether the shell thickness is
increased or not. Stringers usually take the form of a web plate with flat
facing bar.
In tween deck spaces in the forward 15 per cent of the ships length inter-
mediate panting stringers are fitted where the unsupported length of tween
frame exceeds 2.6 m in lower tween decks or 3 m in upper tween decks.
Alternatively the shell thickness may be increased as above.
In the aft peak space and in deep tween decks above the aft peak similar
panting arrangements are required for transverse framing except that the
vertical spacing of panting stringers may be up to 2.5 m apart.
If the fore peak has longitudinal framing and the depth of tank exceeds
10 m the transverse webs supporting the longitudinals are to be supported
by perforated flats or an arrangement of transverse struts or beams.