Where a ship is classed for the carriage of heavy, or ore, cargoes
longitudinal framing is adopted for the double bottom. A closer spacing of
solid plate floors is required, the maximum spacing being 2.5m and also
additional intercostals side girders are provided, the spacing not exceeding
3.7m (see Figure 12).
The double bottom will be somewhat deeper than in a conventional cargo ship, a considerable ballast capacity being required; and often a pipe tunnel is provided through this space. Inner bottom plating, floors, and girders all have substantial scantlings as a results of the heavier cargo weights to be supported.
