Page 353 - Practical Ship Design

310 Chapter 11

Table 1 1.1
Line Type of freeboard EAS%L
0 0.3 0.4 0.5 0.6 0.7 1 .o

1 A 0 21 41 63 100
2 B (F) 0 15 32 46 63 100
3 B(F+B) 0 19 36 46 63 100
4 Timber 20 53 64 70 100

where F indicates with Forecastle but no detached bridge, and F + B indicates with Forecastle and detached
bridge.

Standard heights are:
Raised quarter decks 0.90 m for 24 < L < 30
0.90-1.07 m for 30 < L < 122
1.07 m for L > 122

Other superstructures 1.80 m for 24 < L < 75
1.80-2.3 m for 75 < L < 125
2.30 m for L > 125
The deduction for E = 1 .O L is:
350 mm for L = 24
860 mm for L = 85
1070 mm for L = 122
with intermediate values by interpolation
The percentage deductions for different types of freeboard and different types of
erections are give in Table 1 1.1, again with intermediate values by interpolation.
There are some qualifications to the use of lines 2 and 3.

(vi) Sheer correction
Standard freeboard assumes the ship has standard sheer which is defined as a
parabolic sheer with its lowest point at amidships and ordinates at the:
A.P. of 25 [L/3 + 101 mm
F.P. of 50 [L/3 + 101 mm
The deficiency (+) or excess (-) of sheer is given by the difference between the
actual and standard mean heights of sheer throughout the ship’s length. For para-
bolic sheers this is:
(S, + s, ) - (S, +sa,
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