Question 1

The full secondary-port method corrects…

Accepted Answer

HW and LW, times and heights — four numbers — Real questions usually hang off low water — sills, drying banks — so the LW pair matters as much as the HW pair. All four interpolate on the day’s position between springs and neaps.

Question 2

Today’s range is bigger than the mean spring range. For the secondary-port differences you…

Accepted Answer

Use the springs values — Interpolate between the columns, never beyond them: ranges outside the means take the nearer column’s value. Extrapolation invents data the almanac never measured.

Question 3

A secondary port’s tide times are found by…

Accepted Answer

Applying published time and height differences to a standard port — The almanac lists differences (often different at springs and neaps — interpolate) against a named standard port. The planner’s secondary-port exercise drills exactly this.

Question 4

Around the Solent and some other places, tidal curves show…

Accepted Answer

Stands and double highs — long flat-topped high waters the standard curve method must respect — Local geography distorts the curve; these harbours get their own special curves referenced to LW. Use the published local curve, not the rule of thumb.

Secondary ports without stabilisers

This lesson is part of a paid course