INSTRUCTIONS FOR COMPLETION OF TRIM AND STABILITY LOADING CONDITION FORM
1. Blank forms for calculation of trim and stability for conditions not covered by this booklet are:
Sheet
81A Summary Sheet
81B Details of Ship's Deadweight
81C Details of Cargo Loading
81D Details of Sea Water Ballast
2. Enter weights and free surface on sheets 81B, 81C and 81D as applicable. Compute moments and totals and enter on summary form 81A, and compute summary totals. Take care to enter longitudinal moments as + for Aft, - for Forward.
3. Transverse Stability
Subtract the total VCG (-KG) from KM to obtain the GM uncorrected for free surface. Divide the total free surface by the displacement to obtain the free surface correction and subtract this value from the uncorrected GM. The final result is the GM corrected for free surface, which must be at least 1.2 FT (to suit max required weather criteria GM at IMCO Ballast Draft per superseded Stability Booklet).
4. Trim
Subtract the total LCG from the LCB to obtain the trimming lever. Trim is by stern if LCG is aft of LCB and by bow otherwise. Compute trim by multiplying displacement by trimming lever and dividing by product (MT1 x 12"). For drafts of 32 Ft. or greater and / or small trim, the effect of LCF on trim is small and forward and Aft drafts can be computed by adding or subtraction (to suit trim by bow or stern) half the trim from mean draft. For large trim at drafts less than 32 feet compute draft at bow = mean draft - trim x (352.5 - LCF) / 705. The draft & LCF values are treated algebraically: i.e., the minus signs in the expression change to plus for trim by bow and / or amidships. Draft at stern is draft at bow - trim.