Weather wisdom is more necessary to the man who travels along the coast in a small vessel than to any one else. A large vessel is constructed to encounter any weather with safety, and she must take fair and foul as she finds it; but the safety of a small craft often depends entirely on an accurate forecast of the wind. When the skipper of the little yacht undertakes a voyage, say from Harwich to Rotterdam, he has to pick his weather. He waits in port till he gets a slant—that is, until he has satisfied himself that in all human probability no wind of dangerous strength will blow in the course of the next few days—then he weighs his anchor, hoists his sails, and speeds across the broad sea as fast as he is able, knowing that should a gale of wind spring up before he has made the opposite coast, he will be in considerable peril and not improbably be lost.
But the mariner who has made himself acquainted with the science of meteorology can make a coasting voyage, even in a tiny craft, from one end of Europe to the other, sailing from port to port in favourable weather, and dodging the storms that would infallibly destroy him, by foreseeing them and remaining in snug harbours until they have passed by.
In following the rules which we shall now lay down, the amateur will sometimes find that his forecast of storm will prove a false alarm and will keep him in port idle while he might have been at sea; but on the other hand—and what is far more important—a forecast of fair weather is very rarely wrong; a really dangerous wind is scarcely ever known to spring up without having given a due warning of its approach.
If about to sail from any British port—for instance, across the Channel—in a small yacht, it is useful to remember that one can telegraph to the Meteorological Office, London, for a weather forecast for that particular voyage. The reply—the charge for which is one shilling—will be returned by telegraph without delay.
Such a forecast is more to be relied on than the opinion of all the weather-wise old sailors on the coast.
The weather can be foretold with considerable accuracy by observing the appearance of many natural phenomena, the clouds, the water, the sun and moon, and also by the movements of fish and fowl; but the changes of the barometer are far more to be depended on than the above as indications of coming weather.
Every small yacht should be provided with an aneroid barometer, which is more sensitive and indicates change more quickly than the mercurial barometer, also with a thermometer, and, if the yachtsman wishes to have a complete meteorological outfit, with a hygrometer or wet bulb thermometer. These three instruments will enable him to measure the weight, the temperature, and the degree of moistness of the atmosphere. The last of the instruments mentioned is not often found on a small yacht, and indeed the aneroid and thermometer suffice for ordinary purposes of weather-forecast.
It must be remembered, while foretelling the weather, that the barometer is affected—
Firstly, by the direction of the wind. The greatest rise being with the north-east wind, the lowest fall with the south-west wind.
Secondly, by moisture, an increase of which will cause a fall.