PracticalBoater
Seaworthy | From The BoatUS Insurance Files

 

Preparing For A Hurricane

Wind, Rain And Surge

By Charles Fort
Published: August/September 2014

Tropical storms may be unpredictable, but one thing you can predict is that if one hits your marina, your boat is far more likely to survive if you have a preparation plan and follow it.

Photo of a flooded marina

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Long-range forecasters have learned that trying to predict the number and intensity of the next season's tropical storms is like herding cats. Weather patterns such as El Niño/La Niña, wind shear, and even Saharan desert dust affect the development of tropical storms, and these intertwined variables can confound the best prognosticators, even as the season is starting. As an example, the 2013 season was predicted to have more than average activity, yet it was (thankfully) a yawn. The 2012 season, on the other hand, had twice as many hurricanes as predicted (including Superstorm Sandy). Tropical storms, it seems, don't care about forecasts, and all it takes is one big storm that comes ashore to make seasonal predictions irrelevant. The lesson: Don't wait for the season's forecast before you develop your tropical-storm preparation plan, which is nothing more than knowing what, where, how, and when.

What To Expect

Tropical storms, including hurricanes, produce wind, rain, waves, and surge in proportions rarely experienced by boaters, and storm damage is usually due to a combination of these factors. A good preparation plan has to take all of these elements into consideration and the time to develop one is now, not when a storm is approaching.

How To Prepare For Wind

Photo of removing mast from a sailboat
Removing the mast in smaller sailboats greatly reduces windage.

By definition, tropical storms have winds of at least 39 mph (which is when storms get a name) while hurricanes start at 74 mph and have been recorded at more than 150 mph. What's not always understood is that as the speed of the wind doubles, its force quadruples. In other words, the damage wind does increases much faster than its speed. This illustrates the importance of reducing your boat's windage — the area your boat presents to the wind – by removing as much rigging, canvas, and deck gear as possible. Whether your boat is stored ashore or stays in its slip, the less stuff the wind is able to push around, the safer your boat will be. Biminis are sure to get shredded in a strong storm, so take off the fabric and the frames. Strip off outriggers, antennas, running rigging, booms, life rings, and dinghies. Remove cowling ventilators and seal the openings. Furled headsails have a surprising amount of windage and are one of the first things damaged by wind, so they must be taken down. Not only can they shake your rig apart when they unfurl (and no matter how well you secure them, in a big storm they probably will), they can cause damage to your neighbor's boat as well. Mainsails are bulky and should be removed also.

How To Prepare For Rain

Rainfall of six to 12 inches in 24 hours is common during a hurricane, and as much as two feet can fall in a day. Cockpit scuppers can be overwhelmed by such torrents, and even boats stored ashore can suffer damage if rainwater overflows into the cabin. Boats stored in the water can be sunk when rainwater backs up in the cockpit and the weight forces deck drains underwater, causing them to backflow.

Make certain cockpit drains are free-running. If your boat is staying in the water, remove heavy items from the stern area, such as anchors, extra fuel tanks, and kicker motors, so that the cockpit scuppers are higher above the water. Close all but cockpit drain seacocks and plug the engine's exhaust port. Use masking or duct tape to seal around hatches, ports, and lockers to keep water from getting below. Seal exposed electronics. Make sure the bilge pump and switch work, and that the battery is topped up; shore power is not likely to remain on throughout the storm. Keep in mind that the ability of the pump and battery to remove water is usually greatly overestimated. Small boats should be covered if possible.

How To Prepare For Waves

Tropical storms build up surprisingly large waves quickly, even in relatively small harbors, bays, and lakes. The longer the distance over which the wind can build up waves, the bigger the waves. Waves make boats bounce in their slips, displacing fenders and increasing strain on docklines.

Photo of a swamped powerboat tied to the dock
Exposure to waves can pound a boat against the dock. Small boats should be trailered inland.

Double up on docklines and make sure all are well-protected from chafe. While fenders and fender boards won't compensate for poor docking arrangements, if the boat is well-secured, they may offer some additional protection, especially if they are heavy duty. Smaller boats can be overwhelmed, especially if they are stern-to to the waves. The bow is strongest and least likely to be overcome by water and should face into the waves.

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Lessons From Sandy

Storm Surge

In 2012, Superstorm Sandy reminded all of us that surge can cause at least as much damage as wind. Sandy's surge, which exceeded 10 feet in the hardest hit areas, overwhelmed the infrastructure at hundreds of marinas, floating docks off pilings, destroying fixed docks, and carrying away boats on the hard. It would be easy to conclude that nothing could have prevented the devastation. But boats stood a much higher chance of surviving where boat owners prepared for the surge, and hauled-out boats that were damaged due to the high water suffered significantly less damage than those that remained in the water and floated off with their docks. To know what you're up against, you need to have a good idea of how high the surge will be. In the past, this was mostly guesswork, but now there is a new tool from the National Weather Service (NWS) that can help predict the surge based on your location. The NWS will issue storm-surge prediction maps at around the same time as an initial hurricane watch or, in some cases, a tropical storm watch. These maps will be based on the latest forecast track and intensity for the tropical cyclone and take into account likely forecast errors. They can be thought of as representing a reasonable worst-case scenario for any given location, which can give you advance notice to help you take the appropriate steps to protect your boat.

Storm surge mapClick image to enlarge

Drain Plugs In? Or Out?

In the fall of 2012, many boats had already been winterized when Superstorm Sandy came calling. Most of those boats ended up as total losses — because the drain plugs were out. The surge filled the boats with saltwater and sank them on land, destroying the engines in the process. Dante Grover at Al Grover's High and Dry marina in Freeport, New York, had already winterized some of the boats when he saw Sandy coming. But for those that hadn't been winterized, he decided to leave drain plugs in, make sure bilge pumps were working, add extra bilge pumps, and top off batteries. All of the boats floated off their jackstands or dry stacks, but the boats with drain plugs out were almost all destroyed, while those with drain plugs in were not inundated by the surge and most survived.

Normally, we'd recommend leaving the drain plug out during a storm so that heavy rainwater can drain, but if the possibility of an exceptionally high surge exists and your boat is covered, you may want to leave it in, so water doesn't flow back in. One alternative is a one-way drain plug (such as the CR Marine Automatic Drain Plug). That way, water can drain out of the boat but the plug won't allow water in. One downside to these plugs is that they clog easily, so make sure there's no debris in the boat that could jam in the plug.

 

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