(1) Except as provided for in paragraph (2), the
effective length (E) of an enclosed superstructure of standard height
shall be its length.
(2) In all cases where an enclosed superstructure
of standard height is setin from the sides of the ship as permitted
in regulation 3(10), the effective length
shall be the length modified by the ratio of b/Bs, where:
b 
= 
is the breadth of the superstructure
at the middle of its length; and 
B_{s}

= 
is the breadth of the
ship at the middle of the length of the superstructure. 
Where a superstructure is setin for a part of its length,
this modification shall be applied only to the setin part.
(3) Where the height of an enclosed superstructure
is less than the standard height, the effective length shall be its
length reduced in the ratio of the actual height to the standard height.
Where the height exceeds the standard, no increase shall be made to
the effective length of the superstructure (see figures 34.1 and 34.2).
Where the height, clear of the slope, of a superstructure
which has sloped end bulkheads is less than the standard height, its
effective length E shall be its length S as obtained from figure 34.1, reduced in the ratio of the actual height
to the standard height.
Where a poop or forecastle of less than standard height
is fitted on a ship with excessive sheer but without any superstructure
within 0.2L amidships, credit may be given to the height of the poop
or forecastle by increasing the actual height by the difference between
the actual and the standard sheer profiles. The deduction for excess
sheer in accordance with regulation 38(16) is
not to be granted.
(4) The effective length of a raised quarter deck,
if fitted with an intact front bulkhead, shall be its length up to
a maximum of 0.6L. Where the bulkhead is not intact, the raised quarter
deck shall be treated as a poop of less than standard height.
The maximum effective length of 0.6L of a raised quarterdeck
is to be measured from the after perpendicular, even where a poop
is fitted in conjunction with the raised quarterdeck.
(5) Superstructures which are not enclosed shall
have no effective length.