🔍 Key Concepts
• Load line zones and marks: how Tropical, Summer, and Winter freeboards compare on the same ship
• Change of draft from consumption: using TPI to find how many inches the ship rises as fuel, water, and stores are used
• Dock water vs salt water: using the hydrometer reading and the given fresh water allowance to correct the loading condition
💭 Think About
• Track the voyage day by day: what load line applies at the start, after 6 days, and after 9 days? At each point, what is the maximum allowed draft (minimum freeboard)?
• Calculate the total weight of fuel, water, and stores consumed before entering the winter zone, then convert that to inches of change of draft using TPI.
• Use the hydrometer reading of 1.020 and the 5-inch fresh water allowance to find how many inches of extra sinkage you have in the loading water compared to salt water, and adjust your starting freeboard accordingly.
✅ Before You Answer
• Be sure you are using freeboard values from the deck line given in the table (61" T, 66" S, 71" W) and the fact that T is 5 inches above S and W is 5 inches below S.
• Confirm the total consumption before entering the winter zone: days × 28 tons/day, then divide by 46 tons per inch (TPI) to get inches of change of draft.
• Before picking an answer, verify you have applied both corrections: (1) rise due to consumption of weights, and (2) salt-water correction from hydrometer 1.020 using the 5-inch fresh water allowance.