The stress on the chocks due to the weight of the machinery is known as Deadweight Loading.Deadweight Loading may be limited by the vessel’s classification society and must be determined priorto designing the chocks. Standard values for Maximum Deadweight Loading is 150 N/mm2.
When designing precisely aligned chocks, first calculate the Minimum Required Chock Area. This is calculated by dividing the Total Machinery Weight (including water, oil, accessories, etc.) by the Allowed Deadweight Loading. Design the chocks to cover at least this minimum area. Remember that this is the MINIMUM area. Keep in mind that you may need to increase this area as you work through the calculations. The Actual Chock Area should beequal or greater than the Minimum Chock Area and be based on what is physically possible.