The following questions are to be answered using Chart 13205 TR, Block Island Sound, and supporting publications. Your height of eye is 42 feet and your vessel's draft is 34 feet. The gyro error is 2°E. You are keeping daylight savings time (ZT+4). Use 15°W variation where required.
DEVIATION TABLE Magnetic Heading Deviation 030° 3°W 060° 4°W 090° 3°W 120° 2°W 150° 0° 180° 1°E 210° 2°E 240° 3°E 270° 2°E 300° 1°E 330° 1°W 360° 3°W
At 0400 your position is: Latitude 40° 50.2' North Longitude 071° 36.2' West From your 0400 fix, you steer a course to make good 347°T at 12.5 knots. Visibility is good. What is the earliest time you can expect to raise Montauk Point Light? (Nominal range - 24 miles, height above water - 168 feet)
• Geographic range of visibility using height of eye and height of light • Difference between nominal range (from the Light List) and geographic range • Using speed = distance / time to find when you are close enough to see the light
• First, think about whether the limiting factor is the light’s nominal range (24 NM) or the combined geographic range based on your height of eye and the light’s height above water. • Work out the geographic range in nautical miles by using the tabular or formula method for your 42 ft height of eye and the light’s 168 ft height. • Once you know the maximum range at which the light can appear, determine how far you are from the light at 0400, then figure out how long it takes at 12.5 knots to reach that distance off. • Consider whether you might already be within that range at 0400; if so, think about which answer choices that would eliminate.
• Confirm from the Light List or chart the characteristics of Montauk Point Light, especially height and nominal range (24 NM). • Use the correct height-of-eye and height-of-light visibility table (or formula) and read the values carefully for both heights before adding them. • Double-check your distance at 0400 from Montauk Point Light on the chart and your time-distance-speed calculation at 12.5 knots to see when you enter the geographic/nominal range limit.
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