Planning The Passage

Book Extract

You can often start the overall planning of a summer cruise as far back as the previous winter. This type of long-term planning clearly cannot be detailed, but it does help you decide on the general area you wish to sail in and alerts you to the difficulties you may encounter en route.

You should undertake the more detailed planning of a specific passage perhaps a day or two before sailing, having studied the weather pattern over a period and decided to positively undertake the trip, barring last- minute snags. There are various aspects to this business of planning, the first being a careful analysis of the passage’s component parts.

ANALYSING THE PASSAGE
Most offshore and coastal passages can be considered as three separate stages:

1. Getting clear of the departure harbour, and into a position from which you can set a course to the destination.
2. Sailing to a convenient point outside the approaches to the destination.
3. Approaching and entering the destination harbour. 

The first and the third involve pilotage, while the middle bit is navigation; there is an important difference, and the planning of a passage is much simplified by separating it into these three sections.

Make a start on planning the passage by reading carefully the relevant pilot books, not only for detailed information on the harbors concerned, but also for tidal and other information relevant to the actual passage, Having absorbed this you can then study the charts, paying particular attention to any dangers marked or noted along the track. The clearer your mental picture of the passage at this stage, the easier you will find the actual navigation and pilotage when you might be cold, tired and seasick.

You should also prepare rough plans, make sure you have charts and pilot books for alternative harbours if the weather prevents you making the chosen one. Even if your chosen harbour is accessible in all conditions you must consider the possibility of having to abandon it for other reasons such as lack of time, crew seasickness or weariness, or strong headwinds.

Study and record the weather forecasts for some days beforehand, so you get a clear picture of the way the weather is developing. If time is limited, you can then look ahead to the likely weather prevailing when you want to return, and choose a harbour that will give you a good passage home. This is usually more important than a good passage out — not only because you may have a job to return to, but also because your crew's enthusiasm for hard sailing may have waned by the end of the cruise.

With a general plan worked out you can now turn to the detailed planning of your outward passage. The two most important factors involved in this are leaving at the right time and going in the nght direction; to both of which there is a good deal more than meets the eye. Let us consider the question of timing first.

TIMING THE PASSAGE
Inevitably there will be certain places in a passage which are best negotiated at certain times, and perhaps some that must be negotiated at certain times. You can rarely plan a passage to accommodate them all, so you will have to compromise. The first thing to do is to list all the parts of the passage which will be affected by timing, then sort them into priorities. The likely factors are:

• Any limiting tidal height needed for leaving, due to a drying berth, marina sill, river bar etc.
• Any limiting times for leaving due to difficult or dangerous tidal streams, breaking seas on a bar, lack of shore lights, the need to see drying banks for navigation, and so on.
• The need to pass through races, overfalls or narrow channels, or around headlands at a particular state of the tide.
• The need to carry a fair tide along a coast, or lee-bow a tide across a channel, during certain stages of the passage.
• The desirability of crossing busy shipping lanes in daylight.
• The preference for making an initial landfall at night, when coastal lights are visible for easy fixing.
• The need or desire to approach and enter harbour in daylight.
• Tidal height or stream limitations on approaching and entering the destination harbour, as in the first three points above.
• Whether a few hours delay will allow the current weather pattern to change to a more favourable one; the passage of a cold front, for example, changing murky  south-westerly conditions into clear north-westerly ones.

There are a great many factors here, and it is important to deal with them methodically if you are to make any sense of them.all. Consider the relative importance of each, and the knock-on effects of alternative timings (such as leaving a drying berth on the flood or the next ebb) nght through the passage.

If, for example, you are limited to leaving a marina up to half tide but have no element of danger (such as a breaking bar) to contend with, you may find that staying in your cosy bunk for an extra three or four hours until the ebb may enable you to catch a fair tide round a troublesome headland, or lee-bow a channel tide before tacking towards a windshift (see next section). On a simpler level, there is little point in flogging away to arrive off a small unlit port at midnight, then having to heave-to until dawn, if you can stay in the pub for the evening and go off at first light on a 24-hour passage. But you must always bear in mind the uncertainty of accurately timing any passage under sail. Give yourself a margin of error; you do not want to arrive at a lock gate half an hour after it shuts, with a rising onshore gale and night falling.

SETTING THE COURSE
With a fair wind to your destination, forecast to remain so for the duration of the passage, all you need do is calculate the course to steer, point the boat in that direction, set the sails and put the kettle on. If the wind begins fair, but is forecast to shift ahead, it might benefit you to set course towards one side of your destination so that you avoid having to beat when the wind shifts. This will require some thought, since it will not always be worthwhile. You will need to weigh up the extra time sailed against the timethat might be saved by maintaining a free wind when it shifts. A few sums, some careful weather forecasting, and some geometry will be needed here.

If the wind is inconsiderate enough to be on the nose at the start of the passage, and forecast to remain there, you have three basic ways of dealing with it. The first is to make just two long tacks; the second is to make a number of short tacks; and the third is to go somewhere else — you are, after all, cruising for pleasure!

The first approach minimises the effort and delay caused by frequent tacking, as well as simplifying navigation, but you do risk over- standing your destination when tacking in from a long leg. If the wind shifts you risk being caught dead downwind, just as you are about to stand in on the final leg, or massively over-standing your destination if it frees you. If all goes well, however, it is quicker than short tacking.

The short tacking option removes the risk of overstanding and of being caught downwind in a shift, but does involve more navigation and a greater accumulation of navigational inaccuracies, as well as being slower in theory. On the face of it the choice would seem to be a gamble on the risky efficiency of two long tacks or the slow and fiddly safety of a number of short tacks. The decision as to which approach to adopt is, however, frequently dictated by factors other than personal preference. Let us look at them.

You can greatly reduce the risk of over- standing the destination with two long tacks by putting in the second tack early, producing in effect a passage of three tacks. With a steady wind that is forecast to maintain its direction, this is probably the best course, combining the advantages of both long and short tacking. It is particularly suitable for a small or weak crew, a boat that is slow in stays, or very strong winds in which tacking would be especially wearlsome and time-consuming. If the wind is erratic,creating a danger of being caught downwind at the end of a tack, then you can gradually increase the number of tacks from this ideal until they produce a passage that is close enough to the track to ease your mind. If you gradually reduce the lengths of the tacks as you approach your destination this will reduce the risk of being caught downwind of your goal by a windshift, and also of overstanding.

If the wind is forecast to shift to a particular direction during the passage, start with a single long tack towards the direction of the expected shift. When the shift comes, the boat will be strongly headed and you can tack immediately to take full advantage of the weather gauge that has now been gained. You will need to judge the time of the expected shift carefully, because you could seriously overstand your goal if it comes late. If you plot a limiting line back from the destination which represents the course you can sail close-hauled in the new wind, it will indicate how far you can safely sail away at any stage of the passage without the risk of overstanding when the wind shifts. If you then make your tacks between this line and the new wind direction, you can be sure of a free wind when it comes.

If you experience reasonably strong tidal streams from abeam or thereabouts during the passage, then by and large you should time your tacks so that the tide is always setting up from leeward, underneath the lee bow. This is known as lee-bowing the tide, and it has two benefits: it keeps the boat close to the direct track (in case of windshifts) and it enables you to point higher and sail faster owing to the increase in apparent wind caused by the tide pushing you towards the wind. But this should not normally take priority over sailing towards a windshift for a free wind usually produces greater benefits than that gained by lee-bowingthe tide. If the windshift is expected late, however, you can profitably set up your initial tacks to take full advantage of lee-bowing effects before finally standing off towards the shift.

You can make huge savings in time and effort by planning and executing a passage according to these principles. The key to the whole thing, as ever, is the weather; not one of these tactics is worth twopence unless your weather forecasting is accurate, and I cannot stress too much the value of recording and studying a sequence of forecasts some days before setting off. It is the only way to get a real feel for the way the weather pattern is developing.

 

Taken from Cruising: A Skipper's Guide by John Mellor.

© Not to be reproduced without written permission from Fernhurst Books Limited.