A series of model tests in waves were conducted to measure the shipping water loads that act on deck and hatch covers due to deck wetness. A model of bulk carrier was used. The tests were carried out in irregular waves of which significant height is 10.6 meters and peak period is 14 seconds. In order to discuss the effects of wave heading and ship forward speed on the shipping water loads, the model tests were made in several combinations of wave heading and ship speed conditions. It was confirmed that the deck wetness and shipping water loads will be reduced considerably if the wave heading is altered to the quarter or beam seas or the ship speed is reduced. In order to verify the results of experiment quantitatively, shipping water loads on fore deck and hatch cover were estimated by improving estimation methods that were developed by the author (Ogawa, 1997). Measured shipping water loads were also compared with present rule and requirement for hatch cover. Although it is difficult to directly correlate measured values with the rule and requirement, mean values of measured results tend to be larger than the ones of the rule. It is also found that the shipping water loads defined in the requirement is ranked to somewhere between l/l0 and 113 significant values in relation to the measured results.
A Revision work of International Convention on Load Lines (ICLL66) is carrying out in the International Maritime Organization (IMO) in recent years. Rational revision is needed by the use of the seakeeping theory, which has been progressed after the establishment of ICLL66. Revision work is carrying out gradually. At the present time, revision of regulation especially about minimum bow height and hatch cover is carrying out. (Watanabe et. al., 2000)