and yaw motions of a ship. The effects of such forces are indicated in figure 6-4. Dynamic forces are analogous to those

experienced in an elevator and are most noticeable when the ship recovers from a roll; that is, changes roll direction.

The change in roll direction obviously occurs at the point of maximum roll angle. As noted previously, the cross-deck

component of the item's weight also exerts its maximum force on the dunnage structure at this point. Therefore, the total

maximum force that is applied to the dunnaging structure is equal to the sum of the static and dynamic forces at the

maximum roll angle. Both static and dynamic loads increase with roll angle; the dynamic forces also increase as the

period (duration) of the roll becomes shorter for a given roll angle. Dynamic loads are more severe for "stiff" ships; that

is, ships that demonstrate snap-roll recovery characteristics.

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