Question 1

Forecast is F5 gusting F6, swell 2m, for a 30nm passage with a crew of 3 (two inexperienced). One crew member is already feeling unwell. The skipper wants to complete the passage. Which human factor is most at risk of affecting the decision?

Accepted Answer

Plan continuation bias (also called "get-home-itis"): the commitment to completing the planned passage overrides rational assessment of the risk. The skipper's desire to arrive, combined with the investment already made in departing, creates pressure to proceed despite evidence that conditions exceed the crew's capability. The correct decision: wait for the weather to improve or reduce the passage to a shorter intermediate leg PLAN CONTINUATION BIAS: this is the most common human factor in recreational sailing incidents. The skipper invested time, money, and emotional capital in the planned passage — the psychological cost of turning back feels high. But the risk assessment is objective: F5-6 + 2m swell + inexperienced crew + seasick crew member = conditions beyond the crew's coping capacity. The correct seamanship decision is to wait. MAIB repeatedly identifies plan continuation bias in sailing fatalities where the skipper had clear weather information before departure and proceeded anyway. "The weather I hoped for" is not the weather that was forecast.

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.