Appraise: gathering the information
1The lesson in plain words
Collect everything that affects the passage before you draw a line: charts and books, tides, weather, the boat, the crew and the dangers on the way.
Charts and publications
Collect charts for the whole route, including large-scale charts (detailed views of a small area) of departure, destination and refuges. Apply Notices to Mariners (official chart corrections). Add a cruising almanac, such as Reeds (tide tables, lights, radio and port information), a pilot book or sailing directions (local advice on hazards, harbours and anchorages), and a tidal stream atlas (maps of stream direction and speed).
Tides and streams
Find the times and heights of high and low water, and whether it is springs or neaps. Look up the direction and rate of the streams along the route. They decide when you can leave, cross a bar or enter a harbour, and how fast you will really go over the ground. The Tides and heights and Tidal streams units show the calculations.
Weather
Get the official forecast for the whole passage plus a margin, and the outlook beyond it. Note the wind strength and direction over time, sea state, visibility and any warnings. Plan when and how you will get the next forecast at sea. The Weather windows part shows how to decide.
The boat
Is she fit for this trip? Check engine, fuel and range, water, batteries, rigging, sails, safety equipment and spares. Know her limits: the wind and sea she handles well with this crew, her speed under engine into a head sea, and her draft (depth below the waterline) and air draft (height above it) for every bar and bridge.
The crew
Count who can steer, navigate and handle the boat if you are hurt. Think about experience, fitness, seasickness, cold and tiredness. A passage that suits four experienced sailors can be too much for a couple with one novice. Ask about medical conditions and medicines.
Dangers and rules
List the hazards: rocks, shoals, overfalls, traffic separation schemes (one-way lanes for ships), ferry routes, firing ranges, wind farms, fish farms and navigational warnings, including GNSS (satellite navigation) interference. Check local rules such as speed limits, protected areas and anchoring bans.
2Key data
- Charts
- Whole route, plus large scale for ports and refuges; corrected
- Publications
- Almanac, pilot book, tidal stream atlas, list of lights
- Tides
- High/low water (HW/LW), springs/neaps, stream rates
- Boat limits
- Wind and sea, engine range, draft, air draft
3Key points
- 1
Use corrected charts for the whole route, with large-scale charts of every port you may enter.
- 2
The almanac, pilot book and stream atlas complete the chart.
- 3
Tides and streams often decide when you can leave and arrive.
- 4
Judge the boat and the crew honestly: the weakest link sets the limit.
- 5
List every danger and local rule along the route before you plan it.
4Frequent mistakes
Wrong: Carry a small-scale chart of the whole coast; the plotter has the detail.
Right: Carry large-scale charts or a chart book of the departure, destination and refuges, in case the electronics fail.
Wrong: Plan for the crew at their best.
Right: Plan for them tired, cold and seasick. A passage must still be safe if one person cannot help.
Wrong: The forecast for the morning is enough for a day passage.
Right: Get the forecast for the whole passage plus a margin, and plan when you will get the next update.
5Practice case & exam keys
You plan a 40 M passage along an unfamiliar coast, with a tidal headland halfway and a harbour with a bar at the end. Your crew are your partner, who can steer, and a friend on her first trip.
Show the answer
Check chart corrections, warnings, the headland’s stream and the bar’s depth and entry limits before deciding. Confirm fuel and boat fitness. Your partner can steer, but do not assume either crew member can navigate or manage an emergency. Choose timing and a usable refuge you can manage if one becomes seasick; shorten or postpone if you cannot.
Exam keys
- Appraisal: charts (corrected), almanac, pilot book, tidal stream atlas, Notices to Mariners.
- Tides and streams: times, heights, springs/neaps, rates and directions.
- Boat limits: condition, fuel, draft and air draft; crew limits: experience, fitness, seasickness.
- Dangers: shoals, overfalls, traffic schemes, ranges, warnings and local rules.
Finish this unit
When you've read it, match the terms, then answer three questions. Get them all right to finish the unit; opening the page alone doesn't count.
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