I learned this once by experience. Many years ago, on the coast of New Zealand, I was caught out at sea by a gale of wind in a 13-ft. sailing dinghy, and had to run home before it in a short, dangerous, rapidly rising sea. The little boat tore before the wind under a reefed mainsail and jib, running her nose and stern alternately level with the water, until it became evident that we should be swamped in a few minutes. I ordered the man who was with me to haul down the sail. The moment he did so the little boat, which was sharp at both ends and was steered with an oar, began to ride the seas like a duck, and we ran home before the gale with ease and safety under a bare stick and a fragment of head-sail.
A boat with a sharp stern, steered with an oar, has a great advantage under such circumstances. For the rudder is sometimes right out of the water and useless; and though the water of a great wave does not really move forward with the wave as it appears to do, the breaking top of it does, and when the rudder is in this water, which is going faster than the boat, it is useless for the moment. It is well to have a place for a crutch in the gunwale far aft, so that an oar can be used to steer with if necessary.
There is generally less wind under the shelter or lee of the land. But this is not always the case, and the most experienced seaman cannot always foretell whether this will be so or not. Sometimes the wind seems to belong to the land, and there may be little or none of it out at sea. Under high land--cliffs or mountains--you may lose the wind altogether; you may find it blowing in occasional baffling puffs of great violence and uncertain direction, or you may find it blowing much harder, not in puffs merely but altogether. It is not an uncommon experience, especially in the Mediterranean, to run down a coast before a fresh breeze, and to find a perfect tornado blowing when you turn a corner and luff up under the land. This is one of nature's paradoxes--one of the undoubted facts that one occasionally meets which seem opposed to all reason and probability. I do not know how far it has ever been scientifically explained.
Some places where there is high land seem to brew their own wind. Loch Scavaig, in Skye, under the Coolin hills, is an instance of this. It may be fine and almost calm outside, but as you sail into its gloomy waters you may find a perfect tempest blowing in or out. It staggers one to think what it must be like in a real gale of wind.