When a hurricane is forcast to head your way there are steps that should be taken to protect your boat. Look at the hurricane after photos here to see what happens when you don’t pay attention to anchoring in a storm. Hurricanes are the reason I only sail 11 months of the year here in sunny Florida. I sailed through one once (necessity) and didn’t like it very much.
- First step is always to reduce the boat’s windage by removing all sails, panels, Bimini. Some folks even remove the halyards.
- The top preference is to haul the boat out in advance of the storm to a place that has boat ‘tie downs’ bedded in concrete. If the boat yard doesn’t have tie downs, don’t go there.
- If you can’t haul her out and Mangroves are available, tie the boat into the Mangroves
- No Mangroves? Run the boat up a creek or canal and spider tie the boat. That is multiple lines from every cleat on the boat to land in every direction. (notice a common thread here?…… anchoring the boat to LAND)
- If there are no land tie points then use a minimum of three anchors. Preferably upwind of all other boats. This method is from the famous catamaran author, Charles Kanter’s website. It works well. (see photo below this paragraph) I’ve done it with 3 Fortress anchors coming together in one very large shackle. The Fortress anchors will break before they’ll release if properly set in sand.
- Use chaffing gear.
Chaffing gear can be an old fire hose … or a cut up pair of blue jeans….. anything that protects the rope anchor rodes and allow water and air circulation. Hurricane Andrew in 1992 demonstrated that constant stress will heat up anchoring ropes and over time they will actually melt due to the abrasion of salt crystals embedded in the rope. So any chaffing gear you choose has to allow that heat to dissapate.
- As a side note, after the carnage of the 2004 hurricane season, insurance companies noted that double braided polyester anchor rodes had better performance than the tried and true 3 strand nylon. Books will be rewritten.
- f your boat is fiberglass, then never use all chain rodes if the boat’s not equipped with hause pipes. Chain links can jump, bend or break fair leads and they make a terrific ‘chain’ saw at 100+ knots of wind which goes through fiberglass like butter. There are photos of boats with their bows cut to shreds by chain rode, all over the internet.
- boat positioning. If you have to anchor the boat, always choose the smallest fetch you can find from the strongest predicted wind direction.
Charles Kanter published this diagram of how to anchor a boat in a hurricane in 1995 and to my knowlege no one has improved upon it.
Three anchors come to one point. Use a large shackel to tie the lines together. At this point a 50 pound kedge is attached, as is the bridal. The bridal is 1 boat width long on each leg and terminates on my bow cleats. I use 3 Fortress anchors as we have sand bottoms here and we find them the best holding anchor in sand.
One of the biggest dilemmas is always knowing exactly where the hurricane really going. Forecasts do change and this effects which side of the storm you’re going to be on, and where the strongest winds will come from. By the time the experts are really sure where the storm is going, it’s usually too late and too windy to do all the preps necessary. That’s why this 3 anchor system is preferrable as it allows for wind coming from all directions.
As noted above, try to get up a small river, creek, or canal. Our criteria for a hurricane hole is fairly tight creek or canal with small fetch in all directions. Hills or a berm on both sides are a big plus, but short fetch is most important. (A long fetch will allow big waves and the dynamic loads on your anchors will tend to wrench them out.) When we find “our spot” we decide which direction has the worst exposure and that is the direction we place our biggest anchor on all chain rode. Then we put our other anchors in two or three more directions. We use a single bridle and lead all rodes to it. When our boat is riding on one anchor, the other rodes must have a little slack in them so we can swing 360 degrees without the keels or rudders “tripping” over them. We put a kellet on each of the nylon rodes to keep them submerged when the boat swings over them.
If you don’t have three anchors. You can try just two. Be aware that as you spread the two anchors apart, there is an effect on how much each anchor will load. This diagram below illustrates what happens with a 1000 lb load.
Why all this matters
Two of nature’s forces combine in a storm to become boat killers. They are wind and waves
The formula for wind force shows us that each time wind speed doubles the force of that wind on our boats (or anything else) quadruples). I listed the steps to convert wind speed to pressure on the boat in pounds per square foot below. Try it out by picking some wind speeds and converting them to pressure.
|Begin with any wind speed in miles per hourNext, square the wind speed from line aboveThen, multiply the number from step 2 by coefficient of 0.0027. The result is your pressure in pounds per square feet.lastly, for total pressure on an object, multiply that number times number of square feet exposed|
If we apply this to a practical situation:
|Wind loading||in 100 mph winds||28′ mono||27′ catamaran||36′ center cockpit Morgan||45′ Columbia|
|Boat Total||wind pressure on boat in lbs||1539||1782||2025||8829|
|Boat||Total wind loaded sq ft||57||66||75||327|
|mast||(for mono 6″ wide x 34′ long)||17||17||20||23|
|deck||(for mono -8′ wide x 2.5′ tall) (divide by 2 for angle)||10||14||10||60|
|hulls||(for mono – 10′ wide x 4′ tall) (divide by 2 for angle)||14||15||24||225|
As you can see…wind force alone is significant. All anchors, lines, cleats have to be sized to meet these loads. It should be noted that this approximates a category 3 wind situation. If you are hit by a category 5 storm multiply the wind force x 2.2. At that point, there is no choice but to haul out as no matter what you’ve heard, or what you’ve read … no fiberglass deck mounted cleat will hold against these forces. They will rip out of your deck.