You are loading in a port subject to the tropical load line mark and bound for a port subject to the winter load line mark. You will enter the summer zone after steaming one day, and you will enter the winter zone after a total of eleven days. You will consume 33 tons of fuel, water, and stores per day. The hydrometer reading at the loading pier is 1.004, and the average TPI is 46. What is the minimum freeboard required at the start of the voyage? Reference Table BL-0011 below.
• Load line zones and seasonal freeboards: how tropical, summer, and winter freeboards relate to one another on the same vessel • Consumption during each zone: fuel/water/stores used in the tropical/summer part vs the winter part of the voyage • Fresh water allowance and density correction: using TPI and hydrometer reading to correct the load line in brackish water
• How many days will you be in each zone (tropical, summer, winter), and how many tons will be consumed before reaching the winter zone? • Once you know total tons consumed before winter, how many inches will the vessel rise, using the given TPI? • Starting from the winter freeboard requirement, how far above that must you be when loading in order to (1) allow for the vessel rising due to consumption and (2) correct for the fact you are loading in water that is less dense than salt water?
• Be sure you use total consumption up to entering the winter zone, not the whole voyage consumption • Apply the fresh water allowance in the correct direction: does the ship sit deeper or shallower in fresh/brackish water than in salt water? • Confirm you are finally comparing your calculated starting draft/freeboard to the winter freeboard requirement, not the tropical or summer marks
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