Below the waterline

You’re miles from the nearest land, moving at six to seven knots in a light southwesterly breeze, and you begin to notice the speed dropping off. The boat seems to wallow a bit, steering is sluggish, and it feels like you are dragging a sea anchor or a giant squid. If everything else, the engine and sails, seems to be working fine, you have probably picked up something on your prop, keel, or rudder. And someone is going to have to go over the side to take a look.

Whether you are single-handing or have a crew, this decision is one that you may want to plan for before the actual event. You need at least the minimum diving equipment: a good mask, snorkel, and fins. Minimum tools include sturdy work gloves, a strong stainless steel knife with serrated edge, heavy wire cutters, a hacksaw, and a small hatchet.

If you are a diver and have scuba gear, you may be better prepared to face this situation. If you don’t have any gear, you may choose to free dive and investigate, continue on until you reach shallow water, or just wait and call a professional diver when you reach port.

Many passage-makers and casual cruisers have, stashed somewhere below, an old air tank and some dive gear, held over for just such an emergency. This is fine if you remain current and dive – with the gear – frequently. But I know many skippers who can’t even find their gear when they need it. Old sailing friends of mine once offered to lend me two air tanks they had on board their 35-foot ketch. An hour’s search by them below failed to turn up the tanks. A few weeks later they found them in a locker, under other gear.

If this is your situation, that old tank and regulator could be hazardous to your health. Changes – more than you might expect – have taken place in diving equipment, making it more complex and adding a heavy measure of safety for both recreational and commercial divers.

For example, it is no longer enough to have the tanks inspected by hydrostatic testing every five years. Besides wanting to see your diver credentials, air stations require an annual visual inspection (VIP). Many U.S. air stations have added a further innovation, another inspection called Visual Plus, which checks for cracks in tank walls near the valve. In some areas this has become the required standard.

Cost is another consideration. A full set of dive gear, two-stage regulator with air gauge, back-up air source, buoyancy-compensator vest, weight belt, tank, and wet suit will cost at least $1,500 and take up valuable space on board. For this reason alone, you may choose to own only snorkeling gear.

When to call a diver

Most people only call a diver when they have a problem. They experience reduced performance or feel or hear some unusual vibration, cavitation, or a noise they cannot identify. Or perhaps they just want the green slime removed from the waterline. In a major grounding/salvage situation, periodic insurance inspection, or for installation of new underwater equipment, hiring a diver should be balanced with the cost of a haul-out.

Few boat-maintenance divers advertise, but most marinas and port offices have a list of those available. Ask about prices as well. Most charge by the hour, but some may charge for a combination of time and materials used. In the U.S. you’ll pay anywhere from $60 to $200 per hour, depending on the time of day, immediacy of your needs, local water conditions, and the type of work needed. A diver may quote you a fixed price for a certain job, but this is risky for you if he hasn’t seen your boat or looked at the problem. Because diving is a hazardous and strenuous activity that requires special equipment and high maintenance, expect to pay a diver more than you’d pay someone doing varnish work.

Once you’ve found the diver, discuss what you need. If you say, “I want the bottom cleaned,” and the diver just jumps over the side and disappears for two hours, you have failed to properly communicate. If you are having difficulty with running gear, let him know what spares you have and when the last work was done. For bottom cleaning, discuss what degree of clean you want. Some of our customers say, “Just clean the prop and the rudder.” Those with high-performance boats want a super-clean bottom and running gear. If the bottom is badly fouled with marine growth, it may make more sense to haul the vessel. As the diver works, he may discover things you had not expected. Bent props or shafts, broken instrument transducers, seriously plugged through-hulls, and collision damage may all be uncovered once the diver gets started.

Expect certain limits

An experienced maintenance diver can usually free up anything wrapped around your prop, shaft, and struts. Wire leaders, fishing line, nets, and other debris can cripple your engine quickly, so getting these removed is vital. It takes a diver with scuba gear to do this because the time underwater is more than free divers usually can do. If all you want is the waterline scrubbed, the kids around the anchorage in many countries can do a plausible job with nothing more than mask and snorkel.

The larger the boat, the more complicated the work. Smaller vessels seldom foul trees or submerged logs in their running gear. But larger boats with more equipment below the waterline will inevitably foul bigger, nastier floating or semi-submerged junk.

George W. Baker, one of the best-known rescue scuba divers in the Southeast, tells some hair-raising tales of hours spent trying to free shrimp boats, pilot vessels, and tow craft that had jammed massive logs and other debris in their props. Baker said that this kind of work is most difficult and dangerous because of the tremendous tension that is often set up between the prop, the boat bottom, and debris. “When they come free,” Baker said, “the diver had better be well clear or he faces the prospect of a ton of timber rapping him upside the head.”

The prevailing underwater visibility, depth, temperature, and current will all impact what a diver can do and how long it takes. Black water means working by touch. Strong current means working with one hand and using the other to hang on. Deep-water means anything dropped may not be found. Temperatures will dictate how long the diver can stay submerged and what thermal gear he needs.

Basic maintenance

Zinc (anode) replacement is a common job for divers. We recommend that if your zincs are more than 50 percent used, they should be replaced, as long as the diver is in the water anyway. Most divers charge per zinc in addition to the hourly or per-tank dive fee. You should carry spares to avoid multiple dive charges and trial and error fittings. You should also have any special tools needed for your boat’s zincs, such as Allen (hex) keys. Having these items ready when the diver arrives will cut underwater and pre-dive time.

· Prop work: Changing props is a mixed bag of risk and convenience. Some divers do not want to change props because of potential damage to shaft, stuffing box, and engine while trying to free a wheel that has been in place for an extended period. The size and weight of props is the most critical factor. If you have large, heavy prop(s), the work may require a second diver and/or tackle to lift, safeguard, and lower the hardware. Fitting complex props, such as the feathering models, carries with it the potential risk of losing small parts underwater. Because of the cost of hardware, fitting these props during a haul-out is often a better solution.

· The “quick look below”: Skippers of transient vessels often feel that they have either hit or fouled something in a recent passage. The request to have a diver “just take a look below” is a common order. Most divers are happy to oblige, and this is usually a worthwhile procedure. If everything looks okay, the peace of mind is worth it. If there is a problem, a careful inspection will often discover it. For this type of work, you should figure on a minimum dive of at least an hour, since this is generally the minimum rate anyway. Plan on not less than a minute of inspection time per foot of LOA. It’s best to tell the diver before he enters the water if you want any other type of work performed, such as cleaning through-hulls or ground plates. This is a normal, reasonable request, but if you make it, understand that if more than basic cleaning work needs to be done, the price of the job may change upwards. Here’s an example of how this can happen:

Recently, the owner of a 40-foot ketch on its way to the Bahamas made such a request. “Something is slowing me down and we keep turning right,” he said on the VHF. “Check out the prop and rudder,” came the response from someone on the other end.

A routine inspection of the aft areas and running gear showed that everything was in order. Further investigation revealed that a 12-by-8-inch copper grounding plate, midships on the starboard side, had come unfastened from the bottom and was held by a single, centered through-bolt. The owner had installed the plate, using 3M 5200 adhesive, over the copper-based anti-fouling bottom paint. Seawater, plus the constant flow-by, had eventually broken the seal. Now the plate hung vertical and created nearly a square foot of negative drag, pulling the vessel to starboard. Cutting the plate free with hand tools was difficult work but preferable to a haul-out at that time. The vessel was able to continue onward to the Caribbean the next day. Cost to the owner was $200.

· Helping the diver: Most divers prefer to work either from the dock or barge alongside, but this may not be possible. An inflatable dinghy is useful as a dive tender, and a swim platform makes an excellent workstation. If large, complex, or heavy parts are being passed to the diver, someone from the vessel should be in the dinghy or on the platform to help expedite the work.

· Snags: If you have fouled something in your prop, here’s what should be done. First, the diver makes a short, careful survey to see what is snagged. This will determine the next move. I advise the skipper or crew exactly what I am going to try to do next. They can then be ready to pass me the tools for the job, warn off any approaching vessels, and see to it that no on-board equipment is operated that would affect the diver.

Some snags can be freed without cutting anything. If it’s rope around the prop, the diver may be able to pull it off. If it’s wire or line entangled in a prop or around the shaft, this may not be possible.

Most snags can be freed if the prop was not turning fast at the time of impact. Once a turning prop and a rope connect, the chances are that it must be cut free. Of course, cranking the prop in the opposite direction than when it was fouled might help loosen the tangle.

It is also possible that you will find on the initial survey dive that other debris is involved, such as plastic sheeting or some sort of nets or fabric. Extreme care is called for under these circumstances. Many divers have died entangled in such materials.

· Grounding, collision, sinking: Divers’ services are often necessary to assess damage, assist in salvage or recover important materials. This is specialized and dangerous work. Divers, certified and insured for commercial salvage, and wreck work, are almost always available in big ports, but should you run up on a reef or mud flat far from civilization, you may have to dive yourself or assist a recreational diver. Hazards include unpredictable movement of the vessel, limited visibility, and strong surf or currents. For a vessel aground, lying in quiet water, a diver may be able to ascertain the degree of damage or attach crash pads and tow/lift lines. If towing has failed to pull the vessel free, divers may be able to determine the course of salvage. In a major salvage operation, more complex dive equipment may have to be used.

· Using mixed gases: The use of Nitrox as a diving gas has become more common. Its primary advantage is that it cuts dive fatigue and improves underwater work time under certain conditions. For long-range cruisers, I do not recommend having Nitrox equipment aboard because the gas – air that has been enriched with oxygen usually up to about 40 percent – is difficult to find in most parts of the world. Hired divers may elect to use Nitrox for specialized diving work, and there is no hazard to you if they choose to use it, but it may be more costly. For shallow water work, its use is superfluous.

· Doing it yourself: If you are far from land, have your own scuba or free-diving gear, and must dive, have a plan before you begin. Here’s a 10-point, short planning list for such emergency dives, with and without scuba gear:

1. Survey the problem from on board the vessel as much as possible.

2. Determine what tools you may need.

3. Talk through an entry and exit plan that includes getting the diver back aboard.

4. Prepare ladders, trailing safety lines, diver safety lines and dive gear.

5. Check your equipment. All tools should have a breakaway lanyard so that if dropped they are not lost and if jammed they can break free.

6. Hook up safety lines to the diver and to the boat.

7. Display the Diver Down flag or its international equivalent, flags Alpha and Foxtrot. If in a crowded or high-traffic area, broadcast an alert to other vessels and have someone stand by on VHF.

8. Check water temperature: use wetsuits, skin suits, or even a single clothing layer in cold water.

9. Use an inflatable PFD -not one fitted with hydrostatic release – or buoyancy compensator unit (BCU) on diver(s) and regular PFD’s on all personnel involved in the dive plan. Ideally, have a standby diver ready.

10. If at night, provide plenty of lighting. Light up the boat so that you can see and be seen.

· Different techniques needed: Cutting or prying anything fouled on running gear, especially while holding your breath underwater, is very different from doing so on deck. Under the boat, you have almost no leverage, so tools such as heavy-duty cable cutters will not work as easily for you when you have limited leverage.

Recreational divers will often undertake a dive job that they may not be qualified to do. While safety is the primary factor taught in all diving courses, it is still often under-emphasized when it comes to emergency working dives. If you uncover a situation that appears dangerous or unworkable with the tools, crew, and skills available, call for professional help rather than risk your life or your boat. A diving axiom I learned some years ago is appropriate: When in doubt, get help. When in trouble, have a plan.

By Ocean Navigator