A log is a most useful instrument, not only to register distance, but to tell you what your boat is doing under different sails. There are several logs now made suitable for small craft. By watching the log when you are sailing you can tell whether or not your craft is doing her best. By employing it I have frequently found that a measure that I supposed would add speed has worked just to the opposite. For instance, I have put on more sail, and found by the log that instead of making the boat go faster it has made her move slower. It will also aid you in properly sheeting your sails, so as to get the most effective work out of the canvas. Logs are a great comfort in thick weather, when running for a landfall, as they give you warning of your approach to it, and save a lot of worry. But they must never be implicitly trusted.
Barometers:
Always when cruising carry a barometer, and constantly watch it. This instrument does not foretell the weather except indirectly. It is simply an instrument for measuring the weight of the atmosphere. No change of weather takes place without a change of the weight of the air; therefore, when the barometer remains steady there will be no change. If it goes up or down it means that some change will take place. By learning what usually follows such fluctuations you can employ it to help you in determining or foretelling the future weather conditions.
Weather:
The study of the weather is a most necessary as well as an interesting occupation. To make a success of it you must constantly observe the barometer, the sky, and the sea. By learning the meaning of the colors in the heavens at sunset and sunrise, and by knowing the different forms of cloud, you can nine times out of ten foretell the weather for the next day or two. The color of the sea and its movements are also a guide. The actions of fish, birds and animals, like whales and porpoises, will also aid you. Nothing should be too minute to escape the seaman’s observations, if he wants to become weather-wise.
Winds:
Make a study of the winds in the locality in which you sail. You will find that nine times out of ten they go through the same routine in shifting. By learning the manner in which they change you can take advantage of these shifts. The winds in summer generally follow the sun in its circuit, until they get back to their proper place. If they go the other way, what is called back, you can never trust them to stay long, and it is usually a sign of bad weather. In sounds and estuaries the wind usually comes in with the flood tide. If this tide makes in the morning the wind will stay all day; if the flood makes in the p. m. hours it will not last long. If the wind comes in strong against the tide look out for a long blow. Offshore winds usually come and go with the sun, reaching their maximum velocity at noon and midnight.
Winds:
After a heavy squall you will usually have a calm spell or an offshore breeze. Winds blowing in from the ocean are weaker on the weather side of an island and heavier and puffy on the lee side. On calm nights a gentle air can often be found close under the land, when there is none in mid-channel.