Page 356 - Ship Construction.DJ Eyres 6Ed

Ch31-H8070.fm Page 345 Wednesday, October 18, 2006 7:06 AM
Load Line Rules 345
Having decided the type of ship, the computation of freeboard is
comparatively simple, a number of corrections being applied to the rule
basic freeboard given for Type ‘A’ and Type ‘B’ ships against length of ship.
The length (L) is defined as 96 per cent of the total length on the water-line
at 85 per cent of the least moulded depth, or as the length measured from
the fore side of the stem to the axis of the rudder stock on the water-line, if
that is greater.
--- mmนั้น---
The corrections to the basic freeboard are as follows:
(a) Flush Deck Correction The basic freeboard for a Type ‘B’ ship of not
-----------------------ย์ฝกพาณิชย์นาวี
more than 100 m in length having superstructures with an effective length
of up to 35 per cent of the freeboard length (L) is increased by:

--- ใช้เพื่อการศึกษาเท่า
7.5 100 L–( ) ⎛ ⎝ 0.35 – E⎞ L ⎠

where E= effective length of superstructure in metres.

(b) Block Coefficient Correction Where the block coefficient C exceeds
b
0.68, the basic freeboard (as modified above, if applicable) is multiplied by
the ratio C + 0.68 ึ
งานห้องสมุด ศูน
b
1.36

C is defined in the rules as ∇/(L . B. d), where ∇ is the moulded displace-
b
ment at a draft d, which is 85 per cent of the least moulded depth.

(c) Depth Correction The depth (D) for freeboard is given in the rules.
Where D exceeds L/15 the freeboard is increased by (D–(L/15)) Rmm, where
R is L/0.48 at lengths less than 120 m and 250 at lengths of 120 m and above.
Where D is less than L/15 no reduction is made, except in the case of a ship
with an enclosed superstructure covering at least 0.6L amidships. This
deduction, where allowed, is at the rate described above.

(d) Superstructure Correction Where the effective length of superstruc-
ture is 1.0L, the freeboard may be reduced by 350 mm at 24 m length of
ship, 860 mm at 85 m length, and 1070 mm at 122 m length and above.
Deductions at intermediate lengths are obtained by linear interpolation.
Where the total effective length of superstructures and trunks is less than
1.0L the deduction is a percentage of the above. These percentages are
given in tabular form in the rules, and the associated notes give corrections
for size of forecastles with Type ‘B’ ships.