You want to transit Pollock Rip Channel, MA, on 6 April 1983. What is the period of time around the 0955 (ZD +5) slack in which the current does not exceed 0.3 knot?
• Current tables for Pollock Rip Channel and how to read slack water entries • Understanding how current speed changes over time around slack (minimum current) • Using the rule-of-twelfths / interpolation to estimate when current is below a given knot value
• Look at the table for 6 April 1983 and identify the times and maximum rates of the flood and ebb currents around the 0955 slack. How quickly does the current build on each side of slack? • Ask yourself: for how long before and after 0955 does the current stay at or below 0.3 knot as it changes from one direction to the other? • Compare the pattern of increase in current speed (per 10–15 minute step) to see during which answer choice’s time span the current would stay under 0.3 knot.
• Confirm the reference station and the correct Pollock Rip Channel subordinate station table for 6 April 1983 • Carefully note whether the 0.3 knot limit applies to both sides of slack (before and after 0955) • Check that the chosen time window does not include any period when the predicted current exceeds 0.3 knot in either direction
No comments yet
Be the first to share your thoughts!