Taking a deep breath, I pushed hard off the bottom of the hull and dove down the eight feet to the prop, where the current was such that I had to grip the rudder in one hand to stay in place. I hacked clumsily at the tangled line, which was welded firmly around the shaft and several blades of the propeller. I only managed to cut through one strand before I felt my lungs bursting, so I let go and kicked for the surface, in the process hitting my head against the hull and ignominiously smearing my forehead and nose with bottom paint.
I dove again and again until the line was clear. By this time I was thoroughly exhausted, covered in bottom paint so that it looked as though I had been mauled by a shark, and had several prize bruises on my skull.
These sorts of divesdesperate attempts to clear a fouled prop or a clogged intakebecome inevitable as one spends more time on the water. Thrashing around underwater is exciting and sometimes feels heroicespecially when you first throw off your shirt and announce, “I’m going in!”but it can also be discouraging if the problem is not easily solved with a few dives at shallow depth.
There is an alternative to free diving, however, that many voyagers with recreational scuba experience can appreciate. In recent years several U.S. companies have developed scuba products that may be a boon to voyagers who want the benefit of scuba without the attendant mass of equipment. Products that are touted as emergency scuba gear, considered back-ups for the serious diver, can be kept in a storage locker aboard a small boat for use in situations whenever one needs to spend a few minutes underwater.
It is important to recognize when using these little devices, which can weigh as little as three pounds, that one is breathing compressed air: all the caution normally exercised when scuba diving should be employed. One can dive to 50 or 100 feet with emergency scuba equipment (depending on the size of the tank), but it is too easy to forget that one is still scuba diving, especially for the experienced diver who is accustomed to the weight and feel of standard-size equipment. When going over the side for under-hull work, it may be impractical to dive with a buddy, one of the major rules in recreational diving. For that reason, it is advisable to have a buddy on deck, preferably with a tag line attached to the diver.Most important, remember to ascend slowly and breathe normally at all times, even if ascending from relatively shallow depths of 10 or 20 feet, to avoid risk of barotrauma. Other dangersnitrogen narcosis and decompression sicknessare not as likely with portable scuba units because small tank size limits depth and underwater time.Diver’s certificate requiredAlso to remember that using compressed air underwater requires a diver’s certificate from one of several internationally recognized diving associations, PADI, NAUI, or SSI, etc. Dive shops around the world will not refill tanks without first inspecting a certificate.”It cannot be stressed enough that people who use emergency scuba equipment should understand the dangers involved,” said John Avery, of SEArious Fun/Poseidon in Hauppauge, N.Y., a dive equipment distributing company. “These are very small, handy units, but they work the same way as normal scuba gear.”
As with much shipboard equipment, using portable or emergency scuba systems on a boat involves a series of compromises. A smaller unit will be more compact and cost less, but the drawback is that it holds less air. You can buy a self-contained unit with a 2.7-cubic-foot (cf) tankfor example, the Spare Air unit, produced by Submersible Systems, Inc., of Huntington Beach, Calif. Spare Air gives the average diver about three minutes of underwater time. This is not very much, but it might be enough for a minor task.
Spare Air features a first- and second-stage regulator assembled into one small mouthpiece that is mounted atop the tank without hoses. The whole product is smaller than a quart container of milk and can store almost anywheremounted on a bulkhead or stowed in an emergency bag or in a toolbox.
Another portable unit, the Drop-Weight Cummerbelt, manufactured by Brownie’s Third Lung of Fort Lauderdale, comes with a six-cf “pony bottle” replete with a regulator and padded weight belt. This unit comes with a traditional first- and second-stage regulator that is connected by an air hose. An advantage to having the bottle attached to the belt in a pony bag is that it enables the user to have both hands free for underwater work.
The next size up, a 13-cf tank, is perhaps the most logical size for an emergency scuba system for a voyaging boat, since the tank is still reasonably smallabout 16 inches tall and four inches in diameterbut the 13 to 15 minutes of air is a large enough supply that more involved underwater tasks can be handled.
“A good way to figure out what tank size is needed is to remember that a person under stress burns about one cubic foot of air per minute,” said Julie Footman, owner of Aqua Diving, a dive academy based in Portland, Maine. “And someone who’s got a tangled prop is under stress; kids are screaming at him, his wife’s yelling, and the water’s cold.”
Another option for the voyager interested in having portable scuba gear aboard is to build one’s own emergency kit. In fact, a very basic home-made kit, replete with two 13-cf bottles, can be put together for roughly $500 (see photo, page 87). A no-frills regulator costs about $200, tanks are about $100 each, and assorted buckles, webbing, bottle bag, and weights come to about $100.
The idea is to build a strap assembly out of webbing and a nylon tank bag (or stainless-steel clamps) so that the bottle can be affixed to the weight belt. Added featuresa pressure gauge with a hose ($100) and a filler adapter ($80)make the unit more versatile.
A benefit to using the smallest tank (2.7-cf) is that it can be completely filled by hooking it up to a standard 3,000-psi tank. The Spare Air product comes with a filler adapter, but after several refills even a 2.7-cf bottle cannot be filled to maximum pressure by another bottle. Thus, the capacity of the already-limited tanks becomes further diminished. A larger bottle, the 13-cf for example, can only be approximately half filled when it is hooked up to a larger canister. Only a compressor can top off a tank of this size.
Determining tank time
For obvious reasons, it is important to know exactly how much air is available in a tank so that one does not run out of air at the wrong time. As an experiment, I tested several different tanks, while performing various activities in and out of the water, to determine how much underwater time each tank offered.
My build is roughly average 5’8″, 155 pounds I am reasonably fit and don’t smoke. Even though everyone has a different rate of air consumption, an idea of how much air is available in different tanks can be gleaned by the following examples.
Using Spare Air, which features the 2.7-cf tank, I managed more than six minutes while at rest and about three minutes in cold water and exercising. Considering that the task at hand might be as simple as removing a plastic bag from the raw-water intake (or ill-fated jellyfishsee Chartroom Chatter, page, removing a lobster pot from the screw, or checking the bottom after a grounding, this may be enough time. If the underwater project involves scrubbing the hull or replacing zincs, this is not an appropriate-size tank.
On a full six-cf tank I was able to breathe for almost 10 minutes while at rest. On the other hand, while diving in cold water and swimming hard, I went through the same tank in half the time, about five minutes.
An emergency scuba kit, homemade or otherwise, that holds at least one 13-cf tank might be the most versatile underwater tool, offering substantial time (13 to 14 minutes), but still remaining reasonably compact.
Whatever the choice, it’s clear that having an emergency scuba kit aboard will prove invaluable for those moments when going over the side is not an option but a requirement. It’s also the perfect way to savor a few minutes of peace, immersed and suspended in the silent world, after having completed a long passage of shin-clunking and elbowing for space with shipmates in the confines of a small boat.