(4) Where portable beams for supporting hatchway
covers are made of mild steel, the strength shall be calculated with
assumed loads not less than 3.5 t/m2 on hatchways in position
1 and not less than 2.6 t/m2 on hatchways in position 2
and the product of the maximum stress thus calculated and the factor
1.47 shall not exceed the minimum upper yield point strength of the
material. They shall be so designed as to limit the deflection to
not more than 0.0044 times the span under these loads.
(5) The assumed loads on hatchways in position
1 may be reduced to 2 t/m2 for ships 24 m in length and
shall be not less than 3.5 t/m2 for ships 100 m in length.
The corresponding loads on hatchways in position 2 may be reduced
to 1.5 t/m2 and 2.6 t/m2, respectively. In all
cases, values at intermediate lengths shall be obtained by linear