The good news is that we have a ton of historical weather data on hurricanes. The bad news, much of this data is now worthless. Global warming is rewriting the book. And climate scientists are divided not on global warming but on its long-term effect on hurricanes, their number, and their power. Early predictions were that we’d see many more hurricanes. This hasn’t come to pass. What we have seen thus far are more powerful storms and the season lengthening.
Perhaps now is a good time to take a second look at hurricanes and hurricane safety tips for boaters, as the season begins to peak.
We all know that hurricanes are big, big powerful storms but few us know what specifically defines a hurricane.
A hurricane is a large low-pressure cyclonic weather system that rotates counter-clockwise (in the northern hemisphere) and has sustained winds of over 64 knots (74 mph).
Hurricanes usually contain torrential rains, which often cause severe flooding.
In addition, they can be accompanied by a huge dome of water, called a “storm surge” that is a major cause of damage to low-lying coastal areas.
Never underestimate this threat. Storm surge is why Hurricane Katrina was so destructive to New Orleans in 2005. Over 2,000 people died throughout the impact area when 80% of the city went underwater as a direct result of 53 levees failing. At the mouth of the Mississippi River (Grand Isle), the storm surge was over 26 feet. Thirty oil platforms were destroyed at the same time. Ditto, nine refineries were shut down. The estimated cost was, even at this late date, incalculable. The Bush administration asked for 105 billion dollars which many disaster experts thought was too little, too late. Others put the overall price tag at 150 billion dollars.
New Orleans, her people, and her economy still haven’t fully recovered a decade later.
Hurricanes are ranked 1 to 5 on the Saffir/Simpson Hurricane Scale.
Category I – 74-95 mph
Category II – 96-110 mph
Category III – 111-130 mph
Category IV – 131-155 mph
Category V – 156+ mph
Hurricane Katrina was a Category III as it struck the Louisiana coast, yet it was one of the most destructive weather events in United States weather history because of the flooding and storm surge. In mainland United States, nine out of ten hurricane deaths are caused by storm surge.
In 1970, when a Category V hurricane (called Cyclone Bhola) slammed into Bangladesh, 300,000 people died as a direct result of the massive storm surge.
Just to make a bad situation worse, numerous small tornadoes are formed within the larger storm, and wobble their way around unpredictably. Thus, some homes are completely blown to bits, with houses only a few feet away surviving without major damage.
Tropical hurricanes are truly massive energy systems. In a single day, even a small hurricane produces more energy than most European nations consume in a year.
Hurricane winds can exceed 200 mph. They can also build quickly in strength. One rapidly growing system increased by 85 mph in a single day.
Rainfall amounts can be as high as 36 inches in 24 hours. One hurricane in 1928 dumped two and a half billion tons of water on Puerto Rico. In 1979, Hurricane Claudette poured 45 inches of rain on Alvin, Texas.
Barometric pressure within the eye can be as low as 27 inches.
The ocean waves created by the massive storms can approach 100 feet in height. The wrecks of large ships that were sunk in over a hundred feet of water have shifted their position on the bottom during hurricanes.
In Deshaies, Guadeloupe, (FWI) large cement mooring slabs resting in forty feet of water were tossed on the beach despite having no vessel attached to them during Hurricane Klaus.
Hurricanes vary in size between 25 and 300 miles wide. The center (or eye) averages 15 miles in diameter, but can be as wide as 50 miles (and 50,000 feet high in elevation). Forward speed of the storm averages between 10-15 knots but can speed up to 25-50 knots. They can last for a few hours or, like Hurricane Ginger in 1971, for 28 days.
While the storm surge is usually the killer, the destructive force of a hurricane wind is difficult to comprehend. As wind speed doubles, its ‘pressure’ or force quadruples.
For example, stick your head out of a car speeding along a highway at 50 mph. Feel the force on your face. It’s fairly strong, isn’t it? Well, your face would have sixteen times that force on it if you stuck it out of a stationary car during a very strong hurricane.
The fact that a storm rotates can give you useful information. For example, if you face into the wind of a hurricane in the northern hemisphere, its ‘eye’ can be roughly pointed at by extending your right hand 90 degrees from the wind. You are now pointing almost directly at the center of the storm. Also, if you view your right fist from above (thumb end up), then a hurricane’s wind will rotate in the direction your curled fingers point, counter-clockwise.
Many people find it easier to visualize a storm’s rotation with the help of a couple simple household props. Get a paper plate and a quarter. On the plate, draw a number of arrows around the rim pointing in a counter-clockwise direction. Next take the quarter and place it on the table. Rotate the plate (the hurricane) in a counter-clockwise direction while passing it over the quarter (the island). Do you see how the winds would veer during a north pass? A south pass? A direct hit?
The direction of rotation of a hurricane is a very important concept for a sailor to grasp. If you don’t know a hurricane’s projected path or how it rotates, you will never be able to predict how its winds will veer – one of the most important aspects of storm survival for the mariner.
If the eye of a hurricane passes overhead, the winds will rotate 360 degrees. There will be a period of relative calm within the eye, which might last for a few seconds to a few hours, depending on the location, size, and forward velocity of the storm.
There are five main elements to hurricane survival tips:
- safe harbor
- careful preparation
- proper anchor gear
- adequate knowledge on how to deploy that anchor gear
- and luck.
If any one of these five elements is missing, your vessel will probably be driven ashore and severely damaged or destroyed.
This is the plain, unvarnished truth. Your vessel will probably not survive a direct hit by a Category V hurricane. We regret to inform you of this bleak fact, but the truth is statistically clear. The majority of recreational pleasure craft do not survive a direct hit by a major hurricane.
If you doubt this, just look at the survival rates of yachts anchored in St. Croix, Culebra, St. Thomas, and St. Martin during hurricanes Marilyn, Luis, and Hugo. Or check out what percentage of recreational craft made it through Hurricane Andrew in South Florida or Hurricane Hugo in Charleston, South Carolina.
Many well-known harbors, filled with seemingly “storm-ready” offshore cruising vessels, were literally wiped clean by those storms. Some of the best “hurricane-proof” harbors in the Caribbean had fleet survival rates of less than twenty percent during Hugo and Luis.
Those are not good odds.
The only way to absolutely guarantee that your vessel will not be lost or severely damaged in a hurricane is not to allow it to be in one.
However, it is possible to greatly increase your chances of hurricane survival afloat, if you work at it effectively.
But it is complicated.
If you are reading this as a major storm approaches, don’t despair. You are in imminent danger, but your chances of survival are relatively good, if you properly prepare your vessel.
Major hurricanes can be consistently survived at anchor with only minimum damage to your vessel. There are many vessels that have survived numerous hurricanes down through the years – and yours can join the growing list.
In a word, preparation.
The three basic rules of hurricane survival are
- Move early
- Anchor/moor well, and
- Reduce windage.
You need to move early because thousands of panic-stricken skippers on vessels just like yours will be attempting to cram into a very few safe places.
Many sailors just leave their boats in their normal marina, and hope for the best. Fine. You roll the dice and pray. You can imagine how many boats survive in a marina with pilings normally six feet above high tide-when the storm surge is three or four times that. Zero.
Hauling out is another option. Spice Island Marina on Grenada had 400 boats hauled out during Hurricane Ivan and they fell over. All of them. Zero boats made it through without major damage.
One clever-but-expensive trick is to pre-pay a local shipyard to haul your vessel at the very last moment as the storm builds and then leave it in the slings of the travel lift during the storm. This almost eliminates any chance your vessel will fall over or be damaged by other vessels falling on it. (Rig damage, however, might occur.)
There is hope, however. This writer has experienced over 20 hurricanes afloat with the loss of two vessels. A ten percent loss rate isn’t good. But a 90% survival rate ain’t too bad.
Regardless, in order to survive at anchor you’ll need massive anchor gear correctly deployed. That’s a highly complex challenge and far beyond the scope of this article.
All I can do is wish you good luck, and to assure you that many sailors have been in your Topsiders.