Bad weather prep
How to prepare your boat in harbor and at sea
Signs of approaching bad weather include a falling barometer, a swift change in wind speed or direction, ocean waves from a new direction, a mass of dark clouds in the west, fierce lightning, and warnings over the radio or internet. If any signs appear, follow these suggestions.
Sail away from the storm, especially the “dangerous quadrant” on its right front (left front in southern hemisphere). To predict the path of a low-pressure storm system, use Buys-Ballot’s Law: When you face the wind in the northern hemisphere, low pressure is on your right and high pressure is on your left. (This is because wind circulates counterclockwise around a northern hemisphere low. The low will be on your left in the southern hemisphere, where wind circulates clockwise around a low.)
As a rule, keep the wind in the northern hemisphere on your starboard side to sail away from the approaching storm except when the wind is south to southwest.
Prepare the boat and crew:
- Check the fuel. Make sure your tank is full before leaving.
- Shorten the sail.
- Suit up. Everybody should put on foul-weather gear, life jackets and safety harnesses, which must always be hooked on deck. Rig grab lines in the cockpit and cabin. Take seasickness medication.
- Shut and bolt down hatches and posts, and install washboards in the companionway. Take loose gear off the deck. Put protective panels on large windows, especially on the leeward side, to keep windows from breaking. Below, secure food and other items in lockers. While the boat’s steady, make some hot food and hot water to put in thermoses.
Underway, squalls near shore
Follow the steps above. When black clouds appear and sweep your way, expect a squall. After plotting your position, decide if you have time to return to harbor. (To estimate the distance to a squall in miles, time the interval between the lightning flash and sound of the thunderclap, and divide by five.) Because squalls are unpredictable, it’s often safest to stay in open water well away from land, shoals and other boats.
If your boat is in harbor when a storm approaches, prepare it carefully.
For more information, take our Weather course with a squadron or online.
- Reduce windage. Any exposed area makes the boat sail around its anchor or dock lines, so strip off everything, including all sails, the Bimini and ventilators. Deflate the dinghy and put it in the cockpit. A hard-bottomed dinghy should be sunk or stored ashore.
- At the dock, double or even triple up on dock lines, using plenty of spring lines. Tie leather or cloth chafe protection over lines and fittings. Deploy all your fenders, tying plastic milk bottles full of water to their bottoms to keep them from riding up.
- Set out all your anchors with plenty of scope.
- Close all seacocks and other through-hull fittings.