These notes are condensed from a talk given at a Surrey Schools National Boating Conference. Dinghy navigation necessarily overlaps that practised in keel boats; here it is hoped to deal mainly with those items which proved to be of particular interest at the Conference, or which are unique to dinghies.

1 Tides

A knowledge of tidal heights, times, and streams is essential for the small boat. The simplest route to heights and times of HW is via a table giving the times for every day of the year at a "Standard Port", such as Liverpool, Southampton, etc. To the time obtained from this table one adds a constant for the place you are interested in, e.g. HW Dover July 1st 1962 was 1135. Constant for Burnham-on-Crouch +1.23. Therefore HW Burnham is 1258. (The Admiralty publishes Dover times on a single sheet for 2d, while the constants are obtained from an almanac or local pilot books.

Tidal streams: the flow of the tides, are very important, and information of their speed and direction may be obtained from charts or better still from Admiralty Pocket Tidal Stream Atlases. These are cheap, tough, cloth backed books with separate charts for each hour of the twelve. The direction of flow is indicated by arrows, while the speed at springs and neaps in tenths of knots is given alongside the arrows. When sailing never lose an opportunity to check your ideas on the tide against observable facts, the flow past a buoy or the height up a fixed object.

2 Charts

Unless you are a budding Columbus a chart is essential if you are cruising in new waters. There are three popular sorts, Admiralty, Imray's, and Stanford’s; which sort you choose is rather a personal matter. The Admiralty are, when unfolded, rather large, but are clear in spite of the wealth of detail and are on tough paper which can be folded to a suitable size. Imray's series are intended for yachtsmen and are more suited to the dinghy 'chart table'. The detail and clarity can be less than the Admiralty charts (eg: buoys omitted). Stanford’s are big but are supplied folded and are good in that they give harbour plans as insets and the principal courses are marked in degrees.

When you have bought your chart, learn the signs and symbols, remember whether the depths are given in fathoms or feet and remember that whatever the scale of the chart, one nautical mile always equals one minute of latitude. Maps, while giving practically no information of the sea, may prove very useful for identifying objects ashore, and may help you when picking a landing spot.

3 Pilot Books

No matter how good your charts are, a local pilot book or Yachtsman's guide can supply information which just cannot be put on a chart. These are readily available and a useful selection is kept in the DCA library.

4 In Practice

It is probably time to say that the majority of one's cruising is spent within sight of land or buoys and that little more is required of the navigator than an ability to spot these objects and identify them. What are the limiting factors?

a) Obviously eyesight. If you do wear glasses, take care not to lose them and remember that salt spray very soon cuts down your personal visibility,

b) Even if your eyesight is good, a pair of (nautical) binoculars is a great help. Not too powerful and with a good field of view since you cannot hold them steady in a dinghy. At night a good 'light gathering power' is also essential. The usually accepted size is 7 x 50,

c) The visibility can very easily drop without you realising it. Mist, summer heat haze and the changing direction of the sunlight can all contribute to this effect, so bear this in mind if an object marked 'conspic' on the chart cannot be seen.

d) The earth's surface is curved so you can only see as far as the horizon, and the distance to the horizon (d) is limited by your 'height of eye' (h). The following table gives some values:

(h) ft. (d) miles 3 2 5 2½ 7 3 9 3½

As any object you will look for will have some height of its own, this will contribute to the distance eg: height of eye - 5ft., height of buoy - 3 ft. Total distance: 4½ miles.

5 Compasses

When for one reason or another it is not possible to steer for a visible object, then a compass course must be followed. Selection and installation of a compass in a dinghy is a subject in itself, but no cruising dinghy is complete without some form of compass.

Although it is not possible to steer a very accurate course in a dinghy, it is very comforting to know what the course ought to be, so that an attempt can be made. The method of obtaining a 'course to steer' from a chart is simple enough, but to cover all the possible circumstances of wind and current would occupy far too much space, so the reader is referred to one of the many books on cruising and navigation eg: Eric Hiscock's "Cruising under Sail". In your dinghy the process may well lose some of its accuracy, but at least you will gain some appreciation of the factors involved and the likely errors, and form your plans accordingly.

6 Checks on Position

In coastal waters you may be out of sight of land for any one of a number of reasons, but you are often not very far from the bottom; the use of a sounding device, lead and line, an oar, a spinnaker pole, or even the centreboard can give you information which, when compared with your probable position on the chart, can give you a useful fix.

Further offshore this method is of little use and a radio DF is probably the simplest and most effective method. The Homer Heron equipment is suitable for open boats.

7 Night Sailing

Sooner or later, by intention or by accident, you will find yourself navigating in the dark. Be prepared for this by having a torch to see compass and chart with, and since you are now even more dependent upon these aids, any practise you may have had with them in daylight will now stand you in good stead. However, following the earlier remarks about doing as much as possible by merely looking around you, you may find that if lighted buoys are present, it is easier to identify them and your position in the dark. If there are no lighted buoys remember your sounding gear, which works just as well in the dark (or fog) as it does in daylight!

On starry nights, you can relieve your eyes of ‘compass watching’ by sighting on a star. Make sure you stick to the same star; the ability to recognise the main constellations will help in this and also give you a sense of direction. Remember, however, that they are not fixed in direction, apparently moving from east to west at a rate dependent upon their declination or angle with the equatorial plane.