The charted depth alongside the south face of Mystic Pier, Charlestown, MA, is 35 feet. Your maximum draft is 38 feet. You wish to have 2 feet under the bottom, on a rising tide, when you go alongside to discharge a heavy lift. What is the earliest time after 0900 EST (ZD +5), on 2 February 1983, that you can dock?
• Tidal height needed above chart datum to safely dock with desired under-keel clearance • How to use the Boston tide table for 2 February 1983 to find times when that tidal height exists on a rising tide • Difference between chart datum (sounding) and actual water depth at a given time
• First, calculate the total water depth required at the pier based on your draft and desired under-keel clearance, then compare it with the charted depth. • From that, determine the minimum tide height you must have above chart datum. Then look on the tide table for when the rising tide will give you at least that height. • Be careful to use the correct time zone and date from the tide table and confirm you’re using the prediction for the correct station (Boston area).
• Confirm you are adding draft + desired clearance and comparing that against the charted depth to get the minimum tide height needed. • Verify you are choosing a time when the tide is flooding (rising), not ebbing, at the moment you plan to dock. • Double-check the time conversions: tide table reference (likely LMT or standard time) vs given time format (EST, ZD +5).
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