(1) The sheer shall be measured from the deck
at side to a line of reference drawn parallel to the keel through
the sheer line amidships.
(2) In ships designed with a rake of keel, the
sheer shall be measured in relation to a reference line drawn parallel
to the design load waterline.
(3) In flush deck ships and in ships with detached
superstructures the sheer shall be measured at the freeboard deck.
(4) In ships with topsides of unusual form in
which there is a step or break in the topsides, the sheer shall be
considered in relation to the equivalent depth amidships.
(5) In ships with a superstructure of standard
height which extends over the whole length of the freeboard deck,
the sheer shall be measured at the superstructure deck. Where the
height exceeds the standard the least difference (Z) between the actual
and standard heights shall be added to each end ordinate. Similarly,
the intermediate ordinates at distances of ⅙ L and ⅓
L from each perpendicular shall be increased by 0.444 Z and 0.111
Z respectively.
(6) Where the deck of an enclosed superstructure
has at least the same sheer as the exposed freeboard deck, the sheer
of the enclosed portion of the freeboard deck shall not be taken into
account.
(7) Where an enclosed poop or forecastle is of
standard height with greater sheer than that of the freeboard deck,
or is of more than standard height, an addition to the sheer of the
freeboard deck shall be made as provided in paragraph (12) of this
Regulation.
Measurement of Variation from Standard Sheer Profile
(9) Where the sheer profile differs from the standard,
the four ordinates of each profile in the forward or after half shall
be multiplied by the appropriate factors given in the table of ordinates.
The difference between the sums of the respective products and those
of the standard divided by 8 measures the deficiency or excess of
sheer in the forward or after half. The arithmetical mean of the excess
or deficiency in the forward and after halves measures the excess
or deficiency of sheer.
(10) Where the after half of the sheer profile
is greater than the standard and the forward half is less than the
standard, no credit shall be allowed for the part in excess and deficiency
only shall be measured.
(11) Where the forward half of the sheer profile
exceeds the standard, and the after portion of the sheer profile is
not less than 75 per cent of the standard, credit shall be allowed
for the part in excess; where the after part is less than 50 per cent
of the standard no credit shall be given for the excess sheer forward.
Where the after sheer is between 50 per cent and 75 per cent of the
standard, intermediate allowances may be granted for excess sheer
forward.
(12) Where sheer credit is given for a poop or
forecastle the following formula shall be used:
where
|
s |
= |
sheer credit,
to be deducted from the deficiency or added to the excess of sheer, |
|
y |
= |
difference between
actual and standard height of super-structure at the end of sheer, |
|
L' |
= |
mean enclosed
length of poop or forecastle up to a maximum length of 0.5 L, |
|
L |
= |
length of ship
as defined in Regulation 3 (1) of
this Annex.
|
The above formula provides a curve in the form of a parabola
tangent to the actual sheer curve at the freeboard deck and intersecting
the end ordinate at a point below the superstructure deck a distance
equal to the standard height of a superstructure. The superstructure
deck shall not be less than standard height above this curve at any
point. This curve shall be used in determining the sheer profile for
forward and after halves of the ship.
Correction for Variations from Standard Sheer Profile
(13) The correction for sheer shall be the deficiency
or excess of sheer (see paragraphs (9) to (11) inclusive of this Regulation),
multiplied by
where
|
S |
= |
is the total length of enclosed
superstructures. |
Addition for Deficiency in Sheer
(14) Where the sheer is less than the standard,
the correction for deficiency in sheer (see paragraph (13) of this
Regulation) shall be added to the freeboard.
Deduction for Excess Sheer
(15) In ships where an enclosed superstructure
covers 0.1 L before and 0.1 L abaft amidships, the correction for
excess of sheer as calculated under the provisions of paragraph (13)
of this Regulation shall be deducted from the freeboard; in ships
where no enclosed superstructure covers amidships, no deduction shall
be made from the freeboard; where an enclosed superstructure covers
less than 0.1 L before and 0.1 L abaft amidships, the deduction shall
be obtained by linear interpolation. The maximum deduction for excess
sheer shall be at the rate of 125 millimetres per 100 metres of length
(1½ inches per 100 feet of length).