You are to sail from Elizabethport, NJ, on 22 May 1983 with a maximum draft of 28 feet. You will pass over an obstruction in the channel near Sandy Hook that has a charted depth of 27 feet. The steaming time from Elizabethport to the obstruction is 1h 40m. What is the earliest time (ZD +4) you can sail on the afternoon of 22 May and pass over the obstruction with 3 feet of clearance?
• Tidal height added to charted depth to get actual depth at time of passage • Relationship between draft, clearance, and required water depth • Using the time of steaming to work backward from the time of passing the obstruction to the time of departure
• What total water depth do you need over the obstruction for a 28-foot draft and 3 feet of clearance, and how does that compare to the 27-foot charted depth? • How do you find the exact time in the afternoon tide cycle when the tide gives you that much extra water? • Once you know the time you can safely be over the obstruction, how do you subtract the 1h 40m steaming time to get your earliest sailing time?
• Be clear on whether charted depths are at mean lower low water (MLLW) and what that means for added tidal height • Use the correct tide table date and afternoon (PM) high/low water times for 22 May at Sandy Hook (or its reference port) • Double‑check your time zone designation (ZD +4) when converting or reading times from the tables
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