Previously hatch coamings were erected on the decks of the ships bcfore launching. After launching, hatch covers and fittings together with seal bars, rails, oil jacks and pipes were installed and completed on board. On compeltion, hose testings and operation tests were carried out before inclining test and sea trial. In view of the critial planning and processing required within the overall schedule of the ship in the above method of installing coamings and covers, the authors have endeavoured to improve on this method as follows. The unit comprises the hatch coaming and steel hatch covers completed and fittings located in place. The units are constructed in the assembly areas of the shipyard and erected on to the deck before launching.Therefore, work on fittings can be commenced soon after launching. Due to the adoption of this method the authors succeed in completing hatches etc. about two weeks earlier than by previous method, together with an approximate reduction in cost of 40%. At the beginning the author's concern was primarily about quality, and in particular deformation on completion of installation. It was found on completion that deformation was so slight that it could be ignored, proving the quality of the new system.
