Hatch openings

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Container ship hatch openings

Hatch Openings

Hatch openings are cutouts through decks, covered by hatch covers or hatches, for the passage of cargo to holds or the auxiliary access of ship spaces.

Contents

Cargo Ships

In general cargo ships and container ships, hatch openings can present difficulty to the structural soundness of a vessel: the openings are typically through the midship of the vessel, on the strength deck, and run a considerable portion of the breadth, where stress concentrations can be quite high. As clear cargo space is a desired trait of these holds, and without the ability to connect transverses across the hatch opening, racking and torsional deformation can occur. Hatch end beams and hatch end girders are quite large to counter these stresses, with radiused or elliptical corners in the shell plate of the opening to reduce stress concentrations, and box-girders outboard (such as above wing tanks) to maintain longitudinal strength and torsional rigidity. FEA analysis will be carried out to ensure sufficiency of strength.

Bulkers

Hatch openings on bulkers show more variation in relative size than cargo ships, though rarely occupying the same relative breadth or continous length of container ships. As weight-limited designs, bulkers tend to have enough volume through the top of the holds for large cantilevered beams, aiding torsional and racking resistance.

Other hatches

Hatch openings are common for machinery space accesses, auxillary passage ways, emergency escapes, and pass-throughs. Strength considerations are minimal where the size of such openings is limited.

Coamings

Where there is danger of green water on the deck, hatch openings will require a coaming to limit the dangers of water ingress and downflooding. The minimum height varies with the position of coaming on the vessel relative to the bow and waterline.

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