- Local News for Southern Sailors - August 2002 Next Story
FEATURE
Where to Keep Your Boat in a Hurricane
Securing a Boat Ashore 
A study by MIT after Hurricane Gloria found that boats stored
ashore were far more likely to have been saved than boats stored in the water. For many boat owners and marinas, hauling boats is the foundation of their hurricane plan. Some farsighted marinas and yacht clubs have evacuation plans to pull as many boats out of the water as possible whenever a storm is approaching and secure the rest.
There are some types of boats that must be pulled if they are to have any chance of surviving. Smaller, open boats and high-performance powerboats with low freeboard, for example, will almost always be overcome by waves, spray, and rain. Fortunately, most of these boats can be placed on trailers and transported inland.
Boats ashore should be stored well above the anticipated storm surge, but even when boats are tipped off jackstands and cradles by rising water, the damage they sustain in a storm tends to be less severe than the damage to boats left in the water.
Windage is also a consideration. If nothing else, reduce windage as much as possible and make sure your boat has extra jackstands, at least three or four on each side for boats under 30 feet and five or six for larger boats. The jackstands must be supported by plywood and chained together. To reduce windage, some ambitious boat owners on the Gulf Coast dug holes for their sailboat keels so that they presented less windage. Smaller sailboats were laid on their sides.
Recent storms have proven that high-rise storage racks are vulnerable in a storm's high winds. Several have been completely destroyed in recent hurricanes. If possible, boats on storage racks should be placed on trailers and taken home.
Securing a Boat in the Water
Any boat in the water should be secured in a snug harbor (don't even think about riding out the storm at sea unless you're the skipper of an aircraft carrier). The trick is deciding which harbors will still be snug and which will be vulnerable if a hurricane comes ashore. Storm surge — high water — is a major consideration. A storm surge of 10 feet or more is common in a hurricane, so a seawall or sandy spit that normally protects a harbor may not offer any protection in a hurricane.
Crowded, rock-strewn harbors are picturesque, but they may not be the best place to keep your boat in a storm. Rocks are hard on boats, should yours break loose, and when a harbor is crowded, the chance of another boat breaking loose and banging into your boat is that much greater.
Finally, what is the bottom of the harbor like? If you plan to anchor, check your charts to see how much water your boat will be anchored in. The best anchoring is usually in sand, followed by clay, hard mud, shells, broken shells, and soft mud. Also, water can sometimes be blown out of the harbor, leaving boats stranded briefly. If this happens, your boat would be better off settling onto anything but rocks.
At a Dock
Members of the BoatU.S. Catastrophe Team estimated that as many as 50 percent of the boats damaged during Hurricane Fran could have been saved by using better dock lines — lines that were longer, larger, arranged better, and/or protected against chafing. If you decide to leave your boat at a dock, you'll need to devise a docking plan that is liable to be far different from your normal docking arrangement. By the time preparations are completed, your boat should resemble a spider suspended in the center of a large web. This web will allow the boat to rise on the surge, be bounced around by the storm, and still remain in position.
Take a look at your boat slip and its relation to the rest of the harbor. For most boats, you'll want to arrange the bow toward open water or, lacking that, toward the least protected direction. This reduces windage. Next, look for trees, pilings, and dock cleats — anything sturdy — that could be used for securing dock lines. With most docking arrangements, lines will have to be fairly taut if the boat is going to be kept away from pilings. The key to your docking arrangement is to use long lines, the longer the better, to accommodate the surge. (A good rule of thumb: Storm dock lines should be at least as long as the boat itself.) You will probably want to use other boat owners' pilings (and vice versa), which calls for a great deal of planning and cooperation with slip neighbors and marina management.
Lines should also be a larger diameter to resist chafe and excessive stretching. On most boats, you should use 1/2" line for boats up to 25', 5/8" line for boats 25' to 34', and 3/4" to 1" lines for larger boats. Chafe protectors must be on any portion of the line that could be chafed by chocks, pulpits, pilings, etc.
Floating docks allow boats to rise with the surge if pilings are sufficiently tall — at least 18 feet above mean high water. With shorter pilings (and most floating docks have pilings that are too short), docks and boats will be lifted by the surge and carried away.
Hurricane Holes: Canals, Rivers, and Waterways
Whenever canals, rivers, or waterways are available, they serve as shelters — hurricane holes — and offer an attractive alternative to crowded harbors and marinas. Your mooring arrangement will depend on the nature of the hurricane hole.
In a narrow residential canal, a boat should be secured in the center with several sturdy lines ashore (the "spider web") to both sides of the canal. This technique was common to most of the boats in canals that survived Hurricane Andrew. Conversely, boats that were left at docks without the benefit of lines to both sides of the canal didn't fare any better during Andrew than boats at marina docks. The boat should be facing the canal's entrance and be as far back from open water as possible. Besides sheltering the boat, being away from the entrance will help to maintain a navigable waterway.
Securing boats in canals near private homes is possible only if you make arrangements with the homeowners whose trees and pilings you will be using to secure your boat. This can be difficult if your boat isn't normally moored in the canal. If your boat is already in the canal, getting other homeowners involved in planning for a hurricane increases the chances that your boat (and theirs) will survive. This is important. All it takes to wreak havoc in a narrow canal is one or two neglected boats coming loose.
In wider canals and waterways, boats should be secured using a combination of anchors and lines tied to trees ashore. The more lines and anchors, the better. Try to find a spot that is well away from open water and that has tall banks, sturdy trees, and few homes. Moor your boat away from the main channel. Other considerations: A hurricane hole that ordinarily takes an hour to reach may take two hours to reach when winds and seas are building; bridges may not open as frequently once a hurricane warning has been posted; or the bridges may be locked down to evacuate cars. (This was the case on the Miami River before Hurricane Andrew.) Plan on moving your boat early.
 Mooring tests have shown the helix anchor has tremendous holding power compared to traditional mushroom and deadweight anchors. |
Mooring in a sheltered location can also be a good alternative to exposed harbors and crowded marinas. A boat on a mooring can swing to face the wind, which reduces windage, and it can't be slammed into a dock unless the anchor or mooring drags.
The first question, then, is: Will your mooring hold? As a result of numerous moorings being dragged during recent hurricanes and northeasters, a search has been under way for a more secure mooring anchor. A BoatU.S. test using a large tug and several types of moorings found moorings that are the least likely to be dragged are the "embedment" type anchors — a helical and an expanding fluke anchor — which are deliberately screwed or driven into the harbor bottom. Traditional moorings — mushroom anchors and deadweight blocks — were far more likely to be dragged with relatively little effort. A mushroom anchor that isn't sufficiently buried has very little holding power. And while the holding power of a mushroom or deadweight anchor can be increased by extending the pennant's scope, you also have to consider the proximity of other boats. Embedment anchors do not rely on scope to increase holding power, but scope must be sufficient to allow for tidal surge.
If you have doubts about your mooring, the chances of it dragging can be reduced significantly by using one or two additional storm anchors to enhance its holding power and to decrease the room your boat will need to swing. An arrangement that uses two anchors (or a mooring and an anchor) set 45 degrees apart has been used successfully to moor boats in storms. Three anchors, if they are set correctly, are even better. Three anchors should be set 120 degrees apart and joined at a swivel.
Whatever arrangement you decide on, it is important to have plenty of scope — at least 10:1 if possible — and a lot of heavy oversized chain. Probably 50/50 is the optimum chain-to-line ratio. A riding weight, or sentinel, placed at the chain/line juncture will lower the angle of pull on the anchor and reduce jerking and strain on the boat. To absorb shock, an all-chain rode must have a snubber (usually nylon line) that is about 10 percent of the rode's length.
Chafe gear is essential on any line, but it is especially important on a mooring line. Recent storms have given dramatic evidence that a boat on a mooring is especially vulnerable to chafing through its pennants (see "Critical Points," on page 7). Unlike a boat at a dock, which is usually sheltered and is secured with multiple lines, a boat on a mooring is typically in a more exposed location and secured with only two pennants, which are under enormous loads and will chafe through quickly if they aren't protected.
Chafe Gear
Chafe protectors are essential on all lines: at a dock, at a mooring, or at anchor. Nylon stretches and absorbs shock, which is good, but this stretching under tremendous loads also works the line against chocks and other contact points.
On moorings or at anchor, the line stretched over the edge of the rail can create sufficient heat to melt the line internally. Polyester (Dacron) has much less stretch, but is significantly more chafe-resistant than nylon. By using a polyester line from the cleat through the chock and then joining it with a nylon line (use two eyes) to the piling or mooring, you get the chafe resistance of polyester and the stretch of nylon.
For a super system, if your chocks are large enough, fit a second, larger-diameter hose around another hose that fits snugly to the polyester line. Drill holes in both hoses, and use cord to tie them securely to the line. In a pinch you can use a single hose. If you need chafe protection quickly, use duct tape (a lot) to secure several layers of heavy canvas to the lines. This won't be as rugged as hose, but it is certainly better than leaving the line unprotected.
Cleats and Chocks
Many boats have cleats and chocks that are woefully inadequate. This problem becomes critical when more and larger-diameter storm lines are used during a storm. If necessary add more and larger cleats and chocks now; they'll make securing the boat easier all year.
Assess the ability of cleats to carry heavy loads. This means making sure all are backed properly with stainless steel or aluminum plates. Marine plywood is OK if it's healthy — free of rot and delamination. On sailboats, winches (if backed properly) and even keel-stepped masts can also be used to secure lines at a dock.
(NOTE: Anchor lines should NOT be secured to the mast, as it creates that much more stretch on the line at the chock, which further increases the chances of chafe failure.)
Don't put too many eggs in one basket by leading numerous lines to a single cleat, even if it is backed properly. Two lines per cleat is probably the maximum. Also, a cleat is not reliable when lines are led perpendicular to the base and the cleat can be wrenched out by the tremendous loads.
Reduce Windage!
Strip all loose gear that creates windage: canvas covers, bimini tops, outriggers, antennas, anchors, running rigging, booms, life rings, dinghies, portable davits, etc. Remove cowl ventilators and seal the openings. Anything on deck that can't be taken off should be lashed securely.
Unstepping masts on sailboats is strongly advised. If this is impractical, sails, particularly roller furling headsails, must be removed. Roller furling headsails create a lot of windage, especially when they come unfurled, which is almost guaranteed to happen no matter how carefully they're secured. All halyards should be run to the masthead and secured with a single line led to the rail. This reduces windage and minimizes flogging damage to the mast. The line can be used to retrieve the halyards.
Preventing Theft
Electronics and other valuable gear should be taken home for safekeeping. Not only are electronics vulnerable when vandals comb through boatyards after the storm, they can also be wrecked by all of the water. Personal belongings and other loose gear (potential missiles) should be taken home and the cabinets and cabin doors secured. All ship's documents should be taken off the boat.
Preventing Water Damage
Remove cowl ventilators and seal the openings. Use duct tape to secure covers over instrument gauges. Duct tape should also be used around hatches, ports, lockers, etc., to prevent water damage below. Close all but the cockpit drain seacocks and bang a plug into the engine's exhaust ports. If the boat does take on water, it will sit lower, and water could back up into the cylinders. (Remember to remove the plug before starting the engine when the storm has passed.)
This article originally printed in Seaworthy, the BoatU.S. Marine Insurance and Damage Avoidance Report. Reprinted with permission. |
