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Global planning of multi-day sea voyage

If we are going to sail for several weeks, we will have to start weeks in advance with a rough planning of the routes and ports we want to visit. Departures on a round-the-world voyage often involve years of preparation. Roughly speaking, we need to plan what route we will sail during the entire period. Practice may well turn out differently, as we are very dependent on the weather.

Ship and equipment

Of course, we need to know the dimensions of the ship. This can be useful if you want to sail under a fixed bridge, for instance or over a sill or sandbank. Of your own ship, you may know, but if you are going to sail on a charter vessel, you need to find out.

In addition, of course, everything should be on board. It is wise to have several checklists for inventory, engine, fuel, radio, lighting, safety and communication, equipment, provisions, ship’s papers, etc.

Weather forecasts

We always make sure we get our hands on the latest weather report just before the trip departs. This reduces the chances of us running into dangerous situations, such as a storm. Wind force and direction will also determine whether we can indeed sail the route we had in mind. For each route, make a note of which VHF channels are important and at what time on which channel current weather reports can be received.

Sun and moon

We find out when the rise and set of both the sun and the moon are. Then we can take that into account in trip planning (arriving in daylight) and the watch schedule (at night, at least a very experienced skipper must be on deck). The moon also gives huge visibility when the sky is clear and it is a world of difference between sailing with a clear sky and full moon or night sailing in the rain.

Tidal current

The tidal current is also essential for trip planning. We base our sailing tactics, departure time, ETA, etc. on this. It is therefore important to know the direction of the current for each time segment and its average and maximum strength. So don’t go into too much detail, because then you won’t get an overview.

Limited passage

Of course, you can think up all the best sailing tactics, but if you cannot leave the harbour when you want to because, for example, there is a sill in front of the harbour entrance that you can only cross at high tide, you will not get very far. Fixed bridges that you can only pass under at low tide can also hinder your passage. Don’t forget the operating times of locks and moveable bridges either.


We roughly plot the route from waypoint to waypoint. As a waypoint, we prefer not to choose a buoy, but a point next to it, as otherwise there is a good chance you will sail into it. Especially if your autopilot is linked to your GPS. You also prefer to choose a point well next to a buoy with a light on it, rather than a blind barrel. When plotting the route, we take into account sandbanks, recommended crossing points of traffic separation schemes, etc. If you need to cross, it is not necessary to draw in a zigzag line. Later, of course, we do take into account unsailed courses when determining the ETA, by multiplying the time by a factor. That factor depends on the ship, wind and wave action.

Then determine the departure time, taking into account daylight arrival, a sill or foreshore and the direction of the current. Then determine the course. Take into account, among other things, all obstacles and busy shipping lanes. Also consider the occurrence of coastal winds, bending effects, divergence/convergence, weather systems, land effects, quay effects, current direction, and so on. Once the headings and distances are known, we can calculate the expected time of arrival. We look at what we encounter along the way and what we can use in navigation such as buoys, RACONs, fires, landmarks, etc.

A Polar Diagram indicates how fast the boat can sail at a certain course relative to the wind and wind speed.
Example A polar diagram: On a course of 45 degrees to true wind (i.e. a downwind course) and a wind speed of 12 knots, we can achieve a boat speed of 6.5 knots.
Example B polar diagramAta course of 90 degrees with the true wind (i.e. half wind) and a wind speed of 6 knots, we can achieve a boat speed of 5.2 knots.

polar diagram

Alternative routes / (alternative) ports

It is wise to decide in advance the places where we can opt for an escape or alternative port. For example, if we arrive at a certain point only after sunset, we will shorten the trip slightly, otherwise we will not be able to arrive by daylight.


Night sailing can be very tough. It is often cold at night and fatigue sets in. Sea sickness also plays up much faster, as sometimes there is no horizon to be seen.

If the number of crew is large (e.g. 6 men), it is possible to create a watchkeeping system that keeps the number of people on deck as small as possible (e.g. 2 men), so there is no need to stay on deck for long. You achieve this by making several groups of alternating people. For example, 3 groups of 2 men means 2 hours on, 4 hours off. It has absolutely no added value to sit with 3 men silently chilling in the cockpit when 2 men can handle it just as well.

With a small crew of, say, 2 people, it is important not to spend too long alone on deck in tough conditions. But the time should be long enough for the other person to catch some sleep.

Further, it is taken into account that the best skipper is on deck at the critical moments. So he should be on deck when entering an unfamiliar port, crossing a traffic route, etc. If the crew is sufficiently large, it is wise not to roster the skipper himself, so that he can decide when to be on deck and when to take his rest. With a two-headed crew, this is not possible and so it must be taken into account that the best skipper is on deck at the difficult times.


You check that you have the sea charts ready in order. In particular, check that you have recent charts of sufficient scale (i.e. with sufficient detail) ready, including for the areas where you might have to seek a port of refuge if the voyage goes differently than planned. Of course, the sea charts should be updated using the Notices to Mariners. Of course, you also check that the digital charts in your on-board computer or chartplotter are installed and up-to-date.


A logbook is required by law. In case of accidents, you will be asked to provide a logbook. It will also help you in case the GPS or chartplotter suddenly fails. A logbook is also useful when handing over during watchkeeping. Moreover, we can spot trends in air pressure, wind and course, among other things, which can be used to adjust our tactics. Finally, it is also very instructive to take out the logbook after each trip and think about what we would do better next time to sail even more effectively. Were the right tactical decisions made? Could we have sailed even safer or faster? By going through this with each other after each trip, you learn a little bit from each trip, which helps you sail at a higher level each time.