HANDLING HEAVY WEATHER
Your first job as skipper is to be aware of the possibility of thunderstorms. Watch the weather maps and reports for a couple of days before you go out to see if there are any cold fronts approaching, which can create squall lines. On the water, keep an eye on any cumulus clouds. Often, they indicate fair weather, but if some start to tower upwards and grow dark, they are potential thunderstorms.
Thunderstorms can move at speeds of 20 knots, meaning a cloud on the horizon can quickly overtake your boat.
If you see a thunderstorm approaching, do not hesitate: head directly for the nearest safe harbor. If you can see lightning, count the seconds until you hear the associated thunder. Divide this number by five and it will tell you the number of statute miles you are from the storm. Do not be complacent if the storm is several miles away. Thunderstorms can move at 20 knots, and a storm on the horizon can be upon you quickly. And lightning can strike several miles beyond the storm cloud itself.
If you can make port and tie in, do so–but make sure you can arrive in advance of the storm. A crowded harbor is not the place to be when the wind starts blowing. The chances of successfully docking are slim, and the wind can drive your boat into other vessels and obstacles. Another tactic, if the water is shallow, is to anchor and ride it out where you are. Just be sure the storm hook is set firmly and be ready to take action if it drags.
If you can't make port, you will have to deal with the storm. Air-mass thunderstorms are several miles across, but you may be able to avoid them if you move fast and early. No such luck with squall lines, which can stretch for hundreds of miles. If you are in a sailboat, get into your foul weather gear early and be sure the VHF and other safety gear are ready and waiting. Furl the sails and start your engine, because a single 60- or 70-knot gust can knock you flat, even if your sails are reefed. One tactic, if you have sea room, is to run off with the wind. You will be in the storm longer but the apparent wind will be less.
Thunderstorms are often preceeded by condidtions that include little or no wind, the proverbial "calm before the storm."
In a power boat, you have a better chance of outrunning a storm, but the same rules apply. If you have to ride it out, prepare the boat immediately. Take down any tall canvas that can act like a sail, or at least open up the panels. If you have the option to steer from a pilothouse or enclosed area, do so. Unless you are anchoring, head for deep water, in order to avoid being blown into shallows. Piloting will be different for every boat and every storm, but knowing your boat can help a great deal. If she doesn't perform well regularly in a following sea, that won't improve with heavy winds and waves. You can prepare yourself by reading up on heavy weather handling and thinking through the scenarios that may work best on your boat.
Whatever your circumstances, power or sail, everyone not needed on deck should be sent below. If you have an open boat, people should get as low as they can. The crew should stay away from metal objects such as masts and rigging. You may want to lower antennas and disconnect electronic devices that are not essential. Because lightning can strike away from the storm cloud itself, you should wait at least 30 minutes after the storm passes before continuing your journey.
And pass it will. Thunderstorms can be violent and dangerous, but they are short-lived. Seldom does one last more than an hour, and often the air is cooler and more pleasant afterward. In fact, if it isn't, suspect that there may be more storms lurking about.
