An increasing number of boats now carry diving gear, both for its recreational appeal and for its practical use in hull maintenance. The advantages of the latter use are many.
The underwater parts of a boat are vulnerable to damage and wear, and if something goes wrong in that area, the condition can deteriorate rapidly. Ready access permits fixing small problems and preventing the development of more serious ones.
There is inherent risk in diving, and underwater work increases that risk. An open-water certification is a minimum requirement to do underwater work safely.
You must be comfortable with your diving skills because working under a boat adds a ceiling between you and air. Think of it as a barrier, capable of movement, with lots of sharp points and hooks that can bang into you and snag your suit. The number one killer of divers is not bends or sharks; it is drowning. Plan every move so that it will be successfully completed. Most important: Don't exceed your limits. If the current is too strong, if wind or wakes make the hul too lively, don't dive. As a working diver, I jump into water running four knots with whirlpools scooting by and near zero visibility, and can complete jobs safely. I am able to do this because I know my limits, having increased those limits slowly and tentatively. Your limits must expand only as you gain experience.
bear in mind that a unit of work under water is many times more difficult than in air. The water medium is 800 times thicker than air, and movement requires more effort. Guard your energy jealously; letting your energy supply run too low is more dangerous than running out of air.
Luckily, the new generation of diving equipment makes it easier to be comfortable and relaxed in the water. The bouyancy compensator jacket with automatic inflator gives push-button control for staying at precisely the desired depth. Standard procedure is to wear a full wet suit, including head gear. The reasons: to conserve precious body heat (energy), which is rapidly conducted away by water, and to protect against cuts and bruises. A wet suit hood nets a 30 percent saving of body heat just insulating your head, and softens the impact when you smack into a barnacle-encrusted rudder.
A nylon-lined wet suit made of stretch Lycra is greatly improved over the old rubber one--you can get into and out of it without exhaustion. Balanced regulators of excellent quality are now available to meet the increased air demands of an underwater worker. Some have adjustable flow valves. There are special tools and procedures that are helpful in underwater tasks--such as attaching a plumber's helper to the hull for use as a handle. This prevents your drifting away from the work site.
Price does not always indicate the worth of a piece of gear. Inexpensive snap hooks on your weight belt are the best way to carry tools. The tool should have a two-inch cord loop running through the handle, secured by a snap. A tool dropped is usually a tool lost; it means climbing back into the boat for a replacement, and it doesn't take too many trips to appreciate the $3 safety snap.
Changing propellers is a simple enough job on land. The main problem when doing this job under water is that everything tends to come loose at one time. The prop, the key and sometimes the puller jump off the shaft in unison. This makes for frantic grabbing and sometimes a search in the silt for lost parts. To avoid that, divide the job into manageable units of work. Remove the cotter pin and swim it and your pliers up to your tender; return with a wrench and short piece of 2" x 4" chock and loosen the nut or nuts. Sometimes the prop is loose-- take care it doesn't come off prematurely. Use nylon cord to tie the wheel puller to a forward section of the shaft. The length must be right--too short hinders your movement, too long guarantees a tangle. Do the same for a heavy prop, securing it to a clear or swim platform topside. Now all you really have to catch is the key. One hand catches it; the other holds the wrench.
In some locations marine growth is particularly severe; the frictional resistance of this growth dramatically steals speed, fuel and efficiency, so cleaning the hull is necessary. Conceivably a costly engine repair job could result from a build-up of barnacles.
When doing this dirty, strenuous job, you need good thick gloves to protect your hands. Barnacle cuts are nasty and jagged, so to avoid them is to prevent infection. The best way to remove them from a fiberglass hull is to pop them off with a semi-flexible scraper, such as a taping knife. The difficulty of removing barnacles depends on the type of bottom paint that has been used. With good, fresh paint a gentle, sliding motion of the scraper removes all traces of shell. The other extreme--no paint--takes much more effort. In this case the angle of attack must be acute, the stroke vigorous. With proper technique, even heavy growth will sheet off. Often the barnacle will break, leaving a crater of shell. A scrubbing motion of the scraper, still at a glancing angle, will remove the remnants without damaging gel coat. Meanwhile, the rubber plunger on the hull useful for this job. The suction need not be broken when you're moving; just slide it along and keep scraping. Slightly tilting the handle increases suction for hard gripping.
Once the hull is clean, the smart skipper keeps it clean with preventive maintenance. The 3M Company makes a scrubbing pad with varying degrees of abrasiveness that is perfect for removing sea grasses and algae from bottom paint. Removing this slimy coating allows the paint to leech and prevents attachments of fouling organisms. Again, the plunger is invaluable as a handhold to counteract the pressure being applied when using the 3M pad.
Speed logs and transducers deserve special attention: Detailed cleaning is necessary to insure accurate readings. Use small tools for small jobs. Take your time; these delicate sensors must be pampered. Through-hull fittings and intake filters should be reamed of all blockage, but be careful. Don't jab too vigorously. You might puncture or loosen the hose on the inside of the hull.
The inexpensive zinc anode performs the important function of protecting your experience running gear; the shaft must be clean to make good electrical contact. Bolting on a new zinc is your basic three-handed job. If you don't have help, you stand a good chance of dropping the stainless steel bolts or Allen wrench. The trick is to keep the bolts and Allen wrench tucked into the cuff of your wet suit sleeve. Remove them one at a time and carefully bolt the two halves of the zinc together. Line up the halves so the holes are top and bottom. Once all bots are in lightly, systematically torque them tight. If the Allen wrench slips, there is a chance the bolt will nt come out of the hole. If you happen to lose a bolt, it is sometimes possible to cannibalize one from the old zinc.
Experience and watermanship gained from underwater maintenance work could be a large factor in managing a crisis at sea. Adequate insurance and a first-class life raft, while nice, are no substitute for your boat. If you hole your hull by striking a submerged or floating object, you enter a situation that is potentially life-threatening.
The immediate action of stuffing the hole from inside and shoring to restrict flooding is sometimes not enough. Covering the hole externally is more efficient, as the outside water pressure helps to hold the patch tightly against the hull. If the damage is inaccessible from the inside of the hull, an external patch may be the only way to prevent a sinking.
A mattress or piece of canvas placed over the hole and held in place by hogging lines around the hull is a good temporary patch. This may be reinforced with wood that is through-bolted or nailed over the patch, and sealed with putty. This type of crisis tests your problem-solving ability. Quick decisions are required, so you must be aware of materials aboard that could be of use.
Running aground is a common crisis, and the usual response of immediately reversing engines is a risk--sinking could result from severe bottom damage. Sand and mud churned up by the props could be ingested into the engine intakes, leaving you powerless and stranded. An intelligent refloating plan is what is needed, and an underwater survey will give valuable data on possible hull damage and bottom contour.
Start at the stern and work completely around the vessel. Observe the vessel, the bottom shape and composition, and the current. Information gained from the survey, when applied to your other seamanship skills, will go a long way toward solving your problem.
The problem of the ocean is awesome. Those who claim victory over it know in their hearts they haven't beaten it; they were just lucky and perhaps clever enough to cooperate with its forces. As a seaman, your understanding gained from each excusion below the surface will reward you with a practical advantage in the future. The wise diver will use them to advantage.
Source Citation:Kelly, Jeff. "Underwater troubleshooting; safety is foremost when venturing underwater for repairs or preventive maintenance; know your capabilities." Yachting 155 (May 1984): 54(2). Popular Magazines. Gale. BROWARD COUNTY LIBRARY. 24 Oct. 2009
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