🔍 Key Concepts
• Seasonal load lines: How winter, summer, and tropical freeboards relate to each other in the table.
• Fresh water allowance (FWA) and dock water allowance (DWA): How to adjust the salt‑water load line when loading in water that is not full salt.
• Consumption of fuel, water, and stores: How changes in displacement over time affect draft and freeboard before entering new load line zones.
💭 Think About
• First, ignoring fuel consumption and density, which seasonal load line (winter, summer, or tropical) is the most restrictive at the departure port? Use the freeboards given in the table.
• Using the hydrometer reading 1.004 and the FWA of 6 inches, how many inches above or below the salt‑water winter mark may you load in this dock water? Be careful with the sign: does less‑dense water make the ship sit deeper or shallower?
• Given the daily consumption and TPI, how much will the draft change before entering the summer zone (day 4) and the tropical zone (day 7)? Does this change ever make the vessel closer to or farther from its limiting load line?
✅ Before You Answer
• Compute the dock water allowance (DWA) as a fraction of the 6‑inch fresh water allowance using the hydrometer reading; confirm whether you should add or subtract this allowance from the winter freeboard.
• Verify which condition actually governs the minimum starting freeboard: the winter requirement in dock water, the condition on entering the summer zone, or the condition on entering the tropical zone after burning fuel.
• After you pick a candidate freeboard, mentally "run" the voyage: check that at departure, at entry to the summer zone, and at entry to the tropical zone, no applicable load line is submerged in salt water.