Hatch beams or hatch webs. Hatch beams, also known as hatch webs, are found in older general cargo vessels.
These are heavy beams, fitting into sockets welded or riveted to the inner side of the hatch coamings. The hatch beams serve to support portable hatch covers. Hatch beams also restore to some extent the transverse structural strength of the vessel, which has been affected by the absence of deck beams over the full breadth of the ship.
In some ships, steel pontoon hatch covers weighing about two tons are used for closing the hatchways, thus dispensing with the hatch beams. These pontoons are handled by the ship’s derricks. The hatchways in shelterdeckers were closed by means of pontoons whilst hatch beams and wooden hatch covers were used for closing the hatchways in the tweendeckers.
In modern ships, a special hatch covering system has been designed which can be operated easily by the winches, saving time, compared with the normal hatch board type. This hatch covering is classified into three categories: the wire or chain pull cover, the hydraulic cover and the side rolling cover. The many advantages of this type of hatch cover make it suitable for use on all types of dry cargo vessels.