Hatchways

Hatchways in the majority of dry cargo ships extend across the deck for approximately one-third of the beam. In special types of ship, e.g. container ships, colliers etc., much wider hatchways are fitted as will be seen from the separate cross-sections of these types.

Special arrangements must be made to compensate for the structural discontinuities caused by these large openings; insert plates of increased thickness may be required at the hatch corners as shown. The arrangement of hatch coaming and adjacent structure with rounded hatch corners is illustrated. Note that the hatch coaming should be extended beyond the corner to form a bracket. The deck opening corners should be well-rounded to a reasonable radius, or eliptical or parabolic in shape, to avoid a concentration of stress at these points.

The deck plating forms an important structural member, especially at the strength deck, in resisting longitudinal stress, but only the plating clear of the hatches can be considered in this respect. If hatchways are made unduly wide, the effective width of this plating is reduced and the thickness has to be increased in order that the cross—sectional area of the steel is maintained.

In addition to the plating, beams will also be cut at hatchways and the ends of the half beams will be connected to the hatch coamings and supported by deck girders. The deck girders are usually integral with the hatch coamings as illustrated. At the ends of the hatchways, in the case of transverse framing and at the sides in the case of longitudinal framing deep hatch end beams will be fitted to support the coamings. A pillar will often be placed near the hatch corners at the intersection of the deck girder and a strong beam.