Grain cargo calculations are important matters as a result of the risks caused by that type of cargo, so ship masters and shipping officers must ensure that the requirements stipulated by the International Maritime Organization are met through all stages of the voyage, This is what we will highlight it in the following article.
Which types of cargoes are covered by the IMO Grain code?
The term grain includes wheat, maize (corn), oats, rye, barley, rice, pulses, seeds, and their processed forms which may behave in a similar way to grain in its natural state.
What are the grain hazards?
Cargo settles downward by 2%.
Both of them effects on ship’s stability that’s why we must comply with all stability requirements at all stages of the voyage
Stability Requirements for Grain loading
The intact stability characteristics of any ship carrying bulk grain shall
be shown to meet throughout the voyage at least the following criteria after
taking into account the heeling due to grain shift.
TTL transverse heeling moment should be less than the allowable heeling moment.
The heel angle due to grain shift shall be not greater than 12 degrees.
The area under curve residual stability area to be not less than .075 meter radians.
The initial metacentric height after F.S.E correction is not less than .3 meters.
Before starting calculations procedures we will review the contents of the grain stability booklet for a bulk carrier vessel together to know what that book has and how we can use it during our calculations.
Introduction to Grain stability video
After watching that video, we can now start the calculation steps for a total transverse heeling moment
How to calculate transverse heeling moment?
TO calculate the transverse heeling moment we need to get the volumetric heeling moment value
𝑇𝑟𝑎𝑛𝑠𝑣𝑒𝑟𝑠𝑒 ℎ𝑒𝑒𝑙𝑖𝑛𝑔 𝑚𝑜𝑚𝑒𝑛𝑡= (𝑣𝑜𝑙𝑢𝑚𝑒𝑡𝑟𝑖𝑐 ℎ𝑒𝑒𝑙𝑖𝑛𝑔 𝑚𝑜𝑚𝑒𝑛𝑡) /(𝑠𝑡𝑜𝑤𝑎𝑔𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 𝑖𝑛 𝑐𝑢𝑏𝑖𝑐 𝑚𝑒𝑡𝑒𝑟)
From curves/tables, we can get volumetric heeling moment value for every compartment Depending on the grain stability booklet for our ship.
The vertical center of gravity correction
We don’t need to apply any correction for a filled compartment with Ends trimmed and Ends not trimmed, in case we used a Vertical center of gravity at 100% full capacity.
For a partially filled compartment, we should multiply the transverse heeling moment read out by 1.12.
let us see how we can calculate the total transverse
heeling moment through that video.