Every cruiser, at one time or another, faces a damage control scenario, wherein a piece gear fails, sometimes benignly, sometimes catastrophically. The “gear” could be anything from a failed raw water hose to a breached hull. If it hasn’t happened to you yet, you’ve been fortunate.
To be sure, a well-maintained vessel is less likely to suffer avoidable failures that require damage control measures, or they may be less intensive. However, regardless of a vessel’s operating condition, difficult to predict events, striking a submerged object or running aground, for instance can lead to flooding and the need quickly and effectively deal with it.
By the same token steering system failures and rig collapses all represent “opportunities” for a vessel’s crew to either rise to the occasion and stem the tide, figuratively as well as literally, or break out the EPIRB and abandon ship. Naturally, the former is preferred wherever possible, keeping the vessel afloat, first and foremost, and then underway, are priorities where damage control measures are concerned.
This is the most common sort of onboard emergency that requires damage control measures, and it’s the one for which every vessel operator and crew should be prepared. There are, however, two types of flooding and they are dealt with differently. The first, flooding, occurs as a result of a breach in the hull, from a collision, grounding or a failed through hull fitting, or underwater hardware such as a strut or shaft log, or, in the case od downflooding, water ingress through an existing breach or opening, a port, hatch or vent, from water on deck or in the event of a grounding and drying out (the vessel heels over and is ultimately left high and dry as the tide falls).
In any of these cases water pours into the boat, often at a prodigious rate. A one inch hole one foot below the waterline will admit 1,200 gallons per hour, while a two inch hole two feet below the waterline will admit over 6,000 gallons per hour. If you’re thinking that a bilge pump can keep up with flood rates like these, particularly the two inch hole example, unless it’s of the ultra-high capacity crash pump variety, you can forget it, it’s simply not practical in most scenarios (see the two part story on bilge pumps in PMM April and May 2009 for more on bilge pumps).
The second type of flooding results from the failure of plumbing within the vessel, a parted raw water or stuffing box hose, or broken rigid plumbing such as a sea strainer, air-conditioning pump or related components (often the result of neglect). The result is the same; however, water enters the hull envelope, albeit at a slower rate in many of these cases.
Fully 40% of all underway sinkings are the result of striking a submerged object, while 16% are the result of a broken propeller shaft or strut, and another 16% the result of damaged or deteriorated below the waterline plumbing.
The watch word where damage control is concerned is preparation. Priority must be given to finding and stemming the source of the leak, then to dewatering the vessel. Doing so means possessing a thorough understanding of your vessel and its various engineering spaces and bilges, and knowing those spaces intimately, this includes knowing the location of every seacock, and ensuring it’s readily accessible and functional on a regular basis, ideally three or four times a year. Conspicuously post a chart identifying the location of every seacock (and fire extinguisher) and through hull fitting, above and below the waterline.
Where down flooding is concerned, in the case of a collision with a submerged object or a grounding, the most challenging aspect of effecting your damage control plan often involves accessing the inside of the hull where the breach has occurred. Cabinetry and other joinerwork often makes this very difficult, particularly if the vessel is equipped with a liner. You should therefore be prepared, to the extent it is possible, to cut, chop or smash joinerwork to get to the source of the leak. This may involve the use of a hatchet, sledge hammer or cordless reciprocating saw (which will of course need to have charged batteries available at all times).
The Damage Control Kit
Once the breach has been accessed, break out your damage control kit, which should include, but by no means be limited to, the following.
- Soft wood plugs (cedar is ideal), or one of the newer synthetic variety. I’m not an advocate of attaching one to every seacock; they get in the way and often deteriorate.
- Two or three one foot square quarter inch thick sections of plywood, these are flexible enough to conform to hull shape.
- Wood or synthetic wedges to put pressure on patches, along with a few various lengths of 2”x2” “timbers” for shoring up a patch.
- Square drive, stainless steel cutting point screws, often called PK (after the manufacturer, Parker-Kalon). These are designed to cut through sheet metal; however, they work very well on wood, fiberglass and aluminum. With a cordless drill, they can be used to secure patches in place.
- Sealant, Fast Cure 3M 5200 is well suited to these repairs, it cures while wet.
- Two part putty-like epoxy, it too cures underwater (Evercoat is one manufacturer http://www.evercoat.com/productDetail.aspx?pID=83 ).
- Waterproof duct or “100 mile an hour” tape, or your favorite equivalent, as well as a roll of self-amalgamating tape.
- A few patches (preferably slightly larger than your 1x1 foot plywood squares) of felt for filling voids. A light blanket also works well.
- An exterior hull patch or collision mat http://www.landfallnavigation.com/collisionmat.html
- Optionally, two part expanding liquid foam, it’s well suited to filling voids and placing pressure on patches.
Of course you can and should make use of other items that are already aboard your vessel, including cushions, pillows, mattresses, hatch covers etc. An engine room hatch with insulation already attached can work very well as a pre-made form fitting patch. If you aren’t up to making your own, damage control kits are available off the shelf from www.SeaKits.com
If the breach can’t be accessed from inside the vessel, you may have to resort to tried and true mariner’s trick of fothering a sail, or placing fabric patch, a collision mat, on the outside of the hull. This technique has been used many times over centuries of seafaring, notably by the crews of the Mayflower and Cook’s HMS Endeavour. If your vessel doesn’t have sails all is not lost, triangular hull patches with lines affixed to each point are available, you simply have to be sure to make one part of your damage control kit.
Give thought to your vessel’s design, what would happen if you ran aground on a falling tide and the vessel was left high and dry? Vessels equipped with vents in the hull could be susceptible to down flooding, and the same could be true of cockpit hatches. Do you have a way to cover or secure these openings?
Internal leaks, those that come from failed hoses or plumbing, may be easier to deal in that in many cases all that’s required to stop the ingress of water it closing a seacock. That may be easier said than done, however. If the leak is, by the time it’s noticed, under water, the finding it and determining if a seacock can stop it may be difficult. If the source of flooding isn’t immediately clear, quickly closing all seacocks, other than those for the engine and generator, makes good sense. Engine and genset plumbing should be inspected as soon as possible thereafter; however, disabling this gear by shutting seacocks can be a liability as it is a source of power for bilge pumps. While, as mentioned earlier, pumps will likely not be able to stay ahead of a leak, they may buy the crew precious minutes to find and fix it, so don’t discount their value entirely.
Failed hoses and pipes should be replaced if possible, and if not patched with tape, hose clamps and/or seizing wire. The same is true for a stuffing box hose, a particularly debilitating failure in that replacement is impossible without hauling the vessel. Be prepared to wrap with plastic, tape and splints if necessary to offer added support.
Many years ago, as a young Naval Sea Cadet, I had the opportunity to undergo damage control training aboard the USS Buttercup, at the naval base in Newport Rhode Island. Buttercup was barge of sorts that floated, and sank at times albeit under controlled conditions, in an indoor pool whose dirty, cold and oily water lent an air of realism the exercise, its flooding and lurching machinations controlled by a salty Chief Petty Officer from a nearby control station.
Using patches, wedges, blankets and mattresses leaks were patched, and the vessel kept afloat using powerful venturi-type pumps. This training drove home several points, chief among them are flooding can be extremely frightening, even when simulated, and you can never have enough DC gear. In light of that, it’s important to be prepared, make sure you have what’s needed in your DC locker, and make sure you thoroughly understand how to use it quickly and effectively.