Page 360 - Practical Ship Design

Freeboard and Subdivision 317

11.4.2 Other details dealt with in the deterministic rules
The rules contain special provisions relating to:
- steps in bulkheads
- the position of peak bulkheads
- the extent of double bottoms
- openings in watertight bulkheads
- shell openings below the margin line
- machinery and system
- electrical installation, etc.
Many of these requirements have a major influence on important details of the
ship, its outfit and machinery, but do not greatly affect the main design aspects
which this book addresses.

11.5 DETERMINISTIC RULES FOR SHORT INTERNATIONAL VOYAGES

Because a ship engaged in a short international voyage is never far from a port, the
rules allow a relaxation in the life-saving appliances carried, provided the ship
meets more severe subdivision requirements, increasing the probability of its
staying afloat after damage or at worst increasing the time available for rescue. The
improved subdivision required for these ships also takes account of the greater
likelihood of a collision or a stranding in the waters in which these ships operate.
The permeability of the spaces forward and aft of the machinery space on these
ships is calculated using the following formula.

U = 95 - 35 b/v
where
b = volume below the margin line and above the inner bottom or peak tanks
used for cargo, stores, coal, oil fuel, fresh water within the volume v.

The Criterion of Service numerals given in 511.4.1 apply except that K for
unberthed passengers = 3.5 m2 and for berthed passengers either this value or that
from the formula given in 8 1 1.4.1, whichever is greater.
The factor of subdivision formula for ships of 131 m or more is slightly
modified from that applying to International voyages, with B being replaced by
BB, which is determined as follows:
17.6
BB=- + 0.20
L- 33

This applies to L 2 55 m (BB has a value of 1.0 for L + 55).