Navigation and Chart work - Passage Making
Making a passage brings together all the planning, pilotage and navigation aspects we have dealt with so far. Every passage will be different and there is no correct way to make a passage.
The guidelines are:
Can you put an accurate position on the chart quickly?
Is the direction you are heading in safe?
When will you arrive at the next turning point?
Will you make the next tide gate in time?
Is the crew going to remain in a suitable condition to run the vessel?
What is the weather likely to do during the rest of the passage?
Whist it is not essential to know exactly where the vessel is, you must know that you are in safe water and your approximate position, also that where you are heading is safe. You should also be able to plot a fix or EP if required.
Plotting an EP means that the logbook should be up to date, and the last entry no longer than 1 hour ago.
The navigator should be constantly checking that the direction the vessel is heading is correct and that it will remain in safe water for a known period of time. On a short trip, this may just require looking at the course over the ground function of the GPS, on a longer leg reference must be made to the future tide and wind direction.
Knowing when you will arrive at the next turning point makes planning easy. With the waypoint function of the GPS, these are ready calculated, but do not place too much faith in it. The time to go function will vary as the boat speed changes.
Without GPS, the navigator must be comparing the distance to go with the speed over the ground for the previous few hours to calculate the next ETA.
Next tide gate
Obviously, the arrival time at the next tidal gate is of primary importance to the navigator. The navigator must know if the vessel will arrive before the gate closes, and if not have plan to deal with this situation.
The yacht should be organised in such a way, that if necessary the voyage could continue indefinitely. It is easy to put off rest or eating on the assumption that you will be in harbour in a few hours, only to find that for some unforeseen situation you will be at sea for an extra 12 hours!
I try to run a boat on the belief that I am at sea, until I get in, not only until the time I had planned to get in to harbour!
Where possible, proper meals should be served up, if this is not going to be an option because of bad weather, sandwiches could be prepared before departure (making sandwiches underway is harder than cooking a meal).
On any passage over 10 hours, a watch keeping system should be planned and adhered to. This may be as simple as people taking a couple of hours below in the middle of the passage, or one of the more formal systems may be required.
An ideal watch system is 3 watches, each taking 4 hours on watch, 8 hours off. One of the off watches does the catering and domestic care of the boat. However, not many pleasure yachts have a large enough crew for this system.
A workable system on a yacht with a small crew is 3 hours on duty, then 3 hours off. If you do this, for the first three days you will be exhausted, after 3 days, your body will adapt.
The minimum period to be off watch should be 3 hours, this allows for a decent rest once you are below and out of your sailing clothes, then time to get ready again before going on deck again.
Ideally, a watch system should roll over so that people are not always on watch at the same time of day every day, it is not much fun always being on watch between 0000 and 0400!
The person who must get plenty of rest is the skipper. It is easy to think you are indispensable and that you must be on hand to deal with any problems. If you do this, you may find that at the critical point at the end of the voyage, you are too tired to make good decisions.
The skipper sometimes has to be a little selfish, and ensure they are well rested!
A little planning can make it much easier for the skipper to go off watch. All passages have difficult parts and easier sections. The skipper should be off watch in the easier parts.
The hard parts of a passage will be: Entering and leaving harbour, dealing with shipping, any hazardous areas en-route.
When the skipper goes off watch, firm instructions must be left with the crew on deck about when to call the skipper. If this is not done, many people will leave calling the skipper up on deck until it is too late.
Depending upon the experience of those on deck, these instructions may include calling the skipper when:
The boat can no longer steer the required course.
The speed falls below a set limit.
The visibility deteriorates.
Any other vessels appear on the horizon.
The wind increases above a certain speed.
I also tell the crew, that I want to be called in enough time to do something about other traffic, not just in time to be a witness!
With a well trained crew, they should be capable of being left to make most of the decisions above, but until you know their abilities, it would be foolhardy not to leave some instructions about when to be alerted.
Before the skipper goes off watch, he must know that the course for the next few hours is safe and that it will place the vessel in the correct position when the tide and weather are allowed for.
Once on a passage it is easy to forget to monitor the weather. The minimum is to record the barometric pressure at hour intervals. Ideally, forecasts should be followed in case of any unexpected changes which may force a change of plan.
The pattern of navigation on a long open water trip follows the following format.
Pilotage out of harbour.
A departure fix, as land disappears.
A course to steer to the destination.
Hourly EPs plotted.
Each time the distance to the destination halves, recalculate the course to steer and ETA.
When land is sighted, plot a landfall fix.
Course to steer to the destination.
Pilotage in to harbour.
In practice, many people rely on the GPS to give their position instead of plotting EPs. If you do this, it is a good idea to still plot an EP each hour; this will act as a check and keep you in practice for the day when GPS is not available.
Even with GPS, you will still need to monitor the course to steer and ETA's, as most sets will not do this for you.
This is the pattern of navigation activity on an open water passage. Obviously, not all the information would be left on the chart at the same time.