Question 1

COLREGS Rule 19 governs conduct in restricted visibility. A radar target is detected dead ahead at 2nm, closing. What action is required?

Accepted Answer

Rule 19d(ii): avoid a course alteration to port for a vessel forward of the beam (risk of collision with a vessel approaching from ahead or from the starboard bow). Best action: reduce speed and/or turn to starboard. Do not increase speed. Do not cross ahead. Sound the fog signal: one prolonged blast (power vessel underway making way) every 2 minutes. Prepare to give way — in restricted visibility no vessel has absolute right of way RULE 19 — RESTRICTED VISIBILITY: Rule 19 applies when vessels cannot see each other visually. It removes the normal hierarchy (Rule 18) — in fog, all vessels are required to proceed at safe speed, use all available means to assess risk of collision, and take action that is safe, early, and substantial. Rule 19d specifically prohibits altering course to port for a vessel forward of the beam unless the other vessel is being overtaken. Turning to starboard, or stopping (heaving to), is the safe default. Never try to accelerate and cross ahead.

Question 2

The standard port (Portsmouth HW) is 1800 hrs, height 4.8m. The secondary port time difference is -0020 and height difference is -0.4m. What is the HW time and height at the secondary port?

Accepted Answer

HW time: 1800 - 0020 = 1740 hrs. HW height: 4.8 - 0.4 = 4.4m. Note: differences are applied directly when given as simple offsets. When height ratios are given (not simple differences) use: (secondary HW - secondary LW) / (standard HW - standard LW) × tidal range Secondary port calculation: apply the time difference algebraically (negative = subtract; positive = add). Height differences work the same way. This example is the simple case where differences are given as absolute values. The more complex case (in reed's and almanac) uses ratio calculations interpolating between MHWS/MHWN differences. Always read the secondary port data carefully — some almanacs give "differences" that require interpolation between spring and neap values based on the standard port's predicted height. This is a core Coastal Skipper exam topic.

Question 3

A skipper is relying entirely on a chartplotter with AIS for passage navigation. What are the key limitations that require maintaining traditional skills?

Accepted Answer

Chartplotter limitations: 1) Chart data may be out of date (new wrecks, changed cardinal marks, silting); 2) GPS antenna failure = no position; 3) Power failure = no display; 4) Small-vessel AIS (Class B) is not fitted to all vessels — canoes, kayaks, small fishing boats, naval vessels are all invisible; 5) Chartplotters can show the vessel in a precise but wrong position (datum error, signal multipath). Maintain paper chart, compass, and watch-keeping skills ELECTRONIC NAVIGATION DEPENDENCE: the RYA and MCA explicitly teach that electronic navigation must be backed up by traditional skills. The most dangerous failure mode is overconfidence — the GPS shows a precise position, but the precision may be wrong (multipath, datum error, chart error). AIS Class B is not compulsory for vessels under 300gt recreational — the majority of vessels the Coastal Skipper will encounter (ferries, fishing vessels, RIBs) may have no AIS. A vessel 200m off track in a channel with GPS can be in danger. Paper chart and compass DR must remain a practised skill.