Exercises

Tides

Height of tide

Using the Harwich tide tables in the almanac, find the height of tide at 21 May, 07:15 UT. Work it on paper with the curve, then check.

Secondary port

HW at Ipswich

Harwich HW is 16 May, 11:05 UT, 4.0 m (range 3.7 m). Apply the Ipswich differences from the almanac: when is HW there, and how high?

Streams

Course to steer

Departing 09 Jul, 14:00 UT at 5 kn from 51.923N 1.300W to 51.978N 1.266W on River Orwell. Use ◆A and the almanac. What course do you steer (°T), and what SOG do you make?

Chartwork

Estimated position

At 16 May, 16:00 UT your fix is 51.939N 1.310W. You steer 135°T and the log reads 6.1 nm after one hour. Using ◆A and the almanac for that hour's stream, plot your EP.

Anchoring

Will you stay afloat?

You anchor near Harwich at 12 Jul, 17:00 UT with 7.9 m on the echo sounder. Your draught is 1.9 m. How much water will you have at the next low water?

Tidal gate

When does the gate open?

You need 2.2 m of tide at Harwich to cross the bank. From 07 Aug, 06:00 UT, when does the height first reach it?

Compass

True to compass

Your plotted course is 190°T on River Orwell (variation 1.8°E). Using the deviation card below, what do you steer on the compass?

Chartwork

Three-bearing fix

On River Orwell (variation 1.8°E) you take hand-bearing compass bearings of three charted marks:

• Felixstowe: 261°M
• N Shelf: 255°M
• Cork Sand Yacht Bn: 138°M

Convert to true, plot the position lines from each mark, and fix your position.