Some materials, like grain especially, tend to slide about almost like a fluid. This would mean that buffeting could cause a dangerous list even if the cargo had been levelled carefully at time of loading. In days gone by, this problem was overcome by the use of ‘shifting boards’ which were vertical wooden partitions which divided what would otherwise be one large free surface into a number of smaller ones to that cargo shifting would not cause a list. If one encounters some older grain charter parties, especially in the short-sea trades, reference will even be found to the shippers having to provide up to 10% of a grain cargo in bags for safe stowage. The bagged cargo would be laid on top of the bulk to stop it shifting, as an alternative to shifting boards. Modern bulk carriers approach this problem differently by shaping the hold to reduce the free surface at the top of the cargo. This is achieved by again having plating at a 450 but this time along the angle between the deck and the side of the ship. This shape has the effect of reducing the free surface within which the fluid-like action can take place. The compartments so constructed are also used for ballast water when required and the ability to put some ballast above the water line instead of all of it in the bottom of the ship makes for a much more comfortable ballast passage for both the ship and those in her. With all the weight at the bottom of the ship a pendulum effect is set up when the ship encounters any sort of heavy weather and you will hear seafarers referring to such a condition as the ship being very ‘stiff’, which is not only uncomfortable but, of course, sets up dangerous stresses in the fabric of the ship.