🔍 Key Concepts

• Effect of adding weight low on GM (metacentric height) • How double bottom (DB) and deep tanks (DT) locations (longitudinally and vertically) affect trim and stability • Using the white pages of the Stability Data Reference Book to see GM change for specific tanks ballasted

💭 Think About

• First, decide whether ballasting low in the ship will increase or decrease GM, and why. • Look at where each listed tank (DB2, DB3, DB4, DB5, DB6, DB7, DT6) is located along the length of the vessel—how will that affect both GM and trim at your current drafts? • Compare the target GM change (from 4.8' to 5.9') with the GM changes shown in the white pages when specific tanks are filled— which combination gets you closest without overdoing it?

✅ Before You Answer

• Verify in the white pages which tanks, when ballasted from empty, show a positive increase in GM for your current displacement/draft range. • Check that the chosen tank combination does not create an excessive trim forward or aft that would move you outside acceptable draft limits. • Confirm that the total GM change from the selected tanks, using the tabulated data, brings GM from 4.8' to about 5.9' (or as close as the book allows).