Features December 2001 Issue

Hull Hole Damage Control

The idea of serious hull damage offshore isn't one most people like to dwell on, but a certain amount of mental and physical preparation only makes sense. PS interviewed some offshore experts on how they plan and what they carry.

It's hard to imagine anything worse than holing your boat at sea. We've all heard the stories… one minute you're sailing peaceably, the next the water is pouring in. Whether it's due to a sprung plank, a killer whale, a rogue container, or coming upon an uncharted coral head, you're now faced with the direst of emergencies. Often the water wins, but before we find ourselves trying to figure things out from the liferaft, let's recognize that a hole in the hull isn't necessarily automatic doom. 

This would be a bad time to cobble up a
damage-control response from scratch.

First of all, it's a rarity.  Second, there are materials and tactics equal to the task. Third, it's a situation in which even a small amount of forethought and preparation, both mental and mechanical, can make the difference between life and death.

We interviewed sailors for this piece who have, between them, sailed more than a quarter-million offshore miles—builders, designers, cruisers, and racers. They shared ideas for fix-it kits, their thoughts and theories on hole-fighting tactics, and the plans they've developed "just in case." One broke the bow off his catamaran in the Southern Ocean, another holed his trimaran at the start of a race on Lake Michigan; all are as ready as accomplished sailors can reasonably be.

Even with all their good advice, we wouldn't presume to try to issue directives on this topic, which is one that, on the best of days, can only be defined as "informed improvisation." So think of this survey as an opener and a pot-churner. If, perchance, you're one of the resourceful few who has dealt successfully with a severe holing incident, e-mail us with a description of your tactics, perceptions, techniques, and materials.

Natural Resistance

A number of factors determine how puncture-proof a boat will be. Steel and aluminum hulls offer good protection. Solid fiberglass laminates are less robust but resist holing better than wood. Composite (cored) hulls have proven perhaps the most vulnerable to  lacerations or abrasions (though their record of impact-resistance is good). The farther you sail from the beaten path, the more you plan to explore areas where the hazards are hard to chart or predict, the more thought you might give to choosing a hull that is resistant to holing.

Hull form is a further consideration: Deep-draft, heavy-displacement designs not only give you a substantial "payload"  or ability to take on water before foundering; their slack bilges, narrow waterplanes, and sharp entries make them both harder to hit directly and more resistant to impact than hard-bilged, wide-bottomed boats with plumb stems. And a light displacement boat will "fill up" faster than a boat with a deep bilge.

Long keels are a plus. Says PS editor-at-large Nick Nicholson, "Our deep, traditional hull with its gradual transition in profile from the forefoot to the long, external iron keel is more likely to ride over debris than a modern boat with a fin keel and spade rudder."

Steve Dalzell, Design Programs Manager at the Landing School in Kennebunkport, Maine, agrees: "High- aspect keels (tall and skinny) are very vulnerable upon grounding. Not only is the impact concentrated on a relatively narrow area where hull and keel are joined, but the force tends to push the aft end of the keel up into the hull and often pokes it right through."

We always wonder a bit at the tales penned by solo adventurers. Who's to know, after all, what really happened out there? But this account from Bill King's Adventure in Depth, colorful as it seems, is more than just a brine-soaked war story. It spotlights  elements that we tend to ignore in projecting our own disaster scenarios (like the impossibility of being in two places at once, the killer effects of fatigue, and the importance of persistence). It also suggests that some of the time-honored "standard procedures" (like a fothering sail to cover the hole) may not work:

"Galway Blazer was holed by a great white shark south of Australia during my circumnavigation. I tacked to raise the hole above the water, but though I tried everything I could think of, I couldn't mend the hole. Freemantle lay only three days away, but I was lengthening, not decreasing the distance by this enforced tack towards the South Pole. Darting between the pump and trying to position the storm jib over the damaged area, I slipped below to inspect the result. It wasn't working. The edges of the canvas were acting not as a collision mat, but as a water scoop. After a day or two, though, a fever of improvisation beset me, and this is when I came up with a pair of waterproof trousers— yellow, shiny, strong. I ran ropes through the legs, nailed them along the bottom edge to the damage, and hauled them taut. They were just the right consistency to stop the leak."

The "fothering sail” was nothing new when Capt. James Cook used it in 1770. After the daunting experience of striking the Barrier Reef well clear of land, he lightened Endeavour and got her afloat. She was holed so badly, however, that her pumps could not keep up with the flow. Smearing a sail with oakum, sawdust, and sheep manure,  the crew lowered it to where suction from the puncture pulled it into place. Eventually, Cook made land and made more permanent repairs.

While relatively few of us carry sheep or their byproducts aboard these days, the principle of using a sail has survived as a sensible first response.  Nicholson, aboard Calypso, writes, "Our storm trysail is small and tough enough to use as a fothering sail to wrap around the hull."

Says John Rousmaniere, author of The Annapolis Book of Seamanship, "Take advantage of the suction to hold something—sail, mattress, almost anything— against the hull that will cut down the inflow."

Round-the-world racer Cam Lewis (Commodore Explorer) carries a 4'x4' cloth made of PVC-type fabric with webbing attached at the corners. "Position this 'collision blanket' with the lines… that's the ultimate defense," Lewis says. "Anything that you can't cover with this patch will send you to the liferaft in a hurry."

Circumnavigator Steve Dashew agrees: "Aboard Intermezzo we carried a 5' diameter pentagonal collision mat filled with 1/2" closed-cell flexible foam and fitted with lines tied to reinforced grommets around the outside five corners."

But do you have time to cover the hole before you plug it? Every incident is likely to be different, but experience and hypothesis suggest that positioning a fothering sail or blanket may be a more complex and lengthier task than it sounds, and might not ultimately leave you time to save yourself. Depending on where the hole is, you might need to plug it immediately.

Location, Location

You can't plug the hole unless you can find it. Getting at the puncture can often prove to be your biggest obstacle. When water fills the bilge the usual suspects are the holes that already exist—through-hulls and shaft openings. The age-old advice about carrying soft wooden plugs for the man-made openings still holds true, but it's amazing how few boatowners follow through.

Attach the plugs to their through-hulls with lanyards—this will minimize fumbling underwater and/or in the dark. Know where there's a hammer to bang them home, and of course you'll have a knife on your belt in case you need to do some quick whittling.

If your hoses are intact and your through hulls are not the culprits, check the stuffing box. Even a small chink in the packing where your propeller shaft exits the hull can produce substantial flow. If the seal is gone around your shaft, hammer rags into the openings and wrap the whole mess with tape. Steve Dalzell recommends self-amalgamating tape —yet another use for Tommy Tape, Rig-Rap, or the other tapes reviewed in the March 2001 PS —but duct tape or electrical tape would suffice in what would certainly be a pinch.

A more likely culprit back where the shaft exits the boat is the hard rubber hose that often links the shaft coupling to the stern tube. This hose can split or vibrate loose, or the hose clamps can fail.

Keelbolts are a third place to look. This is an area where underwater epoxy has proven effective, if the flow is of manageable quantity.

But these are the "easy" holes. What about when you hit something at a random place on your hull below the waterline? That's when finding the spot and getting to it in a hurry can be two of your major problems, even before you can respond to the ingress of water.   Bunks, cabinetry, ceiling strips, floorboards, and tanks, in any combination, might be between you and the puncture.

"I always advise people to carry a hatchet and a pry bar," says cruising guru Don Casey. "You don't know what parts of the boat will have to be gotten out of the way to get you to the leak. Don't chop on bulkheads, don't pry chainplates loose, but otherwise you've got to be fast and ruthless about getting to where you can stem the flow. Also, know your boat. It's a simple thing to walk around her when she's on the jackstands in the yard and tap on the hull. Ask yourself where a puncture at that spot would flow on the inside. Having that picture in your mind might save your life."

Says builder Eric Goetz, "One of the most effective fixes I've heard about was what the Italian crew did on one of the last Whitbread Races. They had a hole in the hull beneath the cockpit. They managed to jam a bucket into it, a regular plastic bucket. It was tapered, and when they stuck shores in behind to hold it there it stemmed the flow to almost nothing for the rest of the leg."

A mattress, cushions, a life jacket—whatever fits the opening will do the job if you can jam it in. Shoring your plug in place may require an amputated spinnaker pole, a boat hook, or some piece of furniture that comes to hand. Does the head door offer any possibilities? A locker cover? A bunk rail?

Once you've stemmed the flow to survivable proportions, turn your mind to fashioning a more permanent patch. Don't stop the pumps, though—a 2" hole one foot below the waterline admits about 50 gallons per minute. The average bilge pump can handle something on the order of 40 gallons per minute.

Pre-Fab vs. What's at Hand
Meade Gougeon of WEST SYSTEM Epoxies says: "I wish I could tell you that this was a great place to use underwater epoxy, but it takes too long and the bond is compromised too much by water to be ideal for fixing holes in the hull. What I use are pre-made plywood patches. I have a series of differing sizes and shapes, but you could almost take a "one-size-fits-all" approach. I use bendable, five-ply birch, 3/16" sheets to form the patches. I pre-drill holes at about 4" intervals around the circumference of each patch and set about an inch in from the edge.  To seal the patches I use stuff called "G-5." We use it in the shop for putting down vacuum bags. It's real sticky and it works well under water. I put this G-5 down outboard of the holes and fasten the patch with self-tapping screws using a cordless drill. It literally is just a matter of seconds before these pre-made patches can be applied almost anywhere. To put on a patch from outside the boat you can't use a cordless drill, of course, but you can go over the side, hammer the fasteners in to start them, and screw them tight by hand. Once you peel the backing off the G-5 sealant it helps hold the plywood in place while you work. You can build it up two or three layers to create a seal that's virtually watertight."

The sea rewards resourcefulness. Those who have brought themselves back alive from a hole in the hull are masters of improvisation, and their invention is inspiring. Take the offshore racers who needed bolts to make their patch successful: They scavenged fasteners from their winch bases and alternator brackets and made it through to the finish.

"We have a variety of materials on board that could be used to patch a small to moderate hole in the hull," Nick Nicholson says. "Our settee and berth tops are 3/8" plywood. This is not particularly strong, but it's flexible enough to be forced into a gentle curve to fit the hull. We also have a large piece of 1/4" Lexan that could be used to create an internal or external patch. We have a variety of pieces of hardwood that can be cut to length to use as shores.

"We carry a lot of clear anodized aluminium angle that can be cut for use as bracing or backing. There's also a big supply of caulking compounds, primarily polysulfides and polyurethanes. We have a huge supply of stainless steel screws and bolts complete with large fender washers to spread the load. We have a vast inventory of drill bits in all sizes; our two cordless electric drills are always charged and have spare battery backs. We have two sets of scuba gear aboard. Our folding, rail-mounted swim ladder makes it easy to get back aboard if we have to work over the side."

As a weight-watching racer, Cam Lewis is forced to pare down his preparations somewhat: "One thing I'd recommend is threaded rod. Cut it to length and use it with nuts and washers to customize fasteners for just about any situation. I keep a gun of 3M 5200 loaded. We worked with Sikamen Resins on our round-the-world trip. They're good in a wet environment. I always take enough cloth, mat, resin, and microballoons to be able to fix stuff. I've never patched a hull, but there's cloth pre-impregnated with resin that kicks off when you expose it to water. Might be good to try."

One device made specifically for hull damage control is the Subrella patch. The principle is clear—stick the umbrella-shaped patch through the hole, open it, and tighten it against the hull. As the manufacturer, D.C.G. Banbury of Oxon, England, notes, sometimes the hole won't be big enough for the folder patch to fit through. In that case, the suggestion is to pass a line with some sort of flotation out through the hole, fish it up outside the boat, tie it to the shaft of the Subrella, then pull the whole assembly back from the inside. In some circumstances, presumably, someone could go into the water and pass the shaft in through the hole.

There used to be another product called the Yacht Saver system—inflatable bags that could be tripped to fill a sailboat's interior and thus keep her from foundering. The system was installed on a number of boats, but now the company phone numbers are no longer in service and a previously established website is now "under construction." It's an interesting concept that might come back.

Have a look at the article describing our test of underwater patching compounds—not a bit of sheep manure in it.

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