Tuesday, July 10, 2007

In an instant

I’ve added something to my safety gear – a wax toilet bowl gasket ring.

The same material helped keep my slip neighbor’s boat afloat the other night.

John, who sails a 1975 Cal 3-30, Stronghold, was on his way to Catalina Island Sunday. He planned to spend the night at Emerald Bay and return Monday in time to watch the first start for the Transpac race, the start for the cruisers and smaller racing boats.

About three hours into his single-handed motorsail Sunday, John heard an unusual noise and his engine seemed to hiccup. It lasted just an instant, he said, and then everything seemed normal. But there shouldn’t be any unusual noises and the engine shouldn’t hiccup, so after thinking about it for several minutes, John decided to throttle back and take a look below.

The Cal 3-30 has great access to the aft end of the engine and the propeller shaft from a side hatch in the starboard quarterberth. Opening the hatch, he was greeted with water gushing in through a broken hose that had secured the propeller shaft's stuffing box to the stern tube through which the shaft exited the boat.

It was a gallons-per-minute leak, a boat-sinking leak, and there was no obvious fix. The propeller shaft remained securely in place, preventing the use of a tapered wooden plug of the sort that can stop a leak from a thru-hull fitting.

When the engine is inside the boat, there has to be some way to get its power to the propeller outside the boat. It is done by running the propeller shaft through a hole in the boat. Water cools and lubricates the shaft. What keeps the water from flooding around the shaft and into the boat is a simple and normally very reliable system called a stuffing box.

The stuffing box isn't really a box. Its not much more than two sections of pipe that surround the prop shaft, one section threaded into the other. An internal gap between the two sections is filled with flax or other material, which prevents the water from coming any further up the shaft, but at the same time does not create any undue friction on the shaft.

The outer section of pipe is the same diameter as the stern tube through which the shaft exits the hull. A length of heavy reinforced hose, much like a car's radiator hose, slips over the stern tube and the stuffing box (pipe) and is held tightly in place by two strong hose clamps at each end. It is designed to drip water while the shaft is turning at the rate of a several drops every minute. (There are other, newer design sealing systems that don't drip at all, but most boats have a traditional stuffing box as described.)

John went back to the cockpit. He shut down the engine, stopped the propeller from spinning, turned the boat back toward the mainland and radioed for help on his marine VHF radio. Sea water soon spilled out of the separate engine bilge under the cockpit and began to fill the lower main bilge in the saloon. Water was pouring in faster than the bilge pump could get rid of it.

Luckily for John he was not yet far from Point Fermin and a Los Angeles County lifeguard boat reached him within about 10 minutes of his mayday call. A high-capacity portable water pump powered by a gasoline engine was quickly put aboard Stronghold, and the water was rapidly sucked out. The leak had flooded the cabin sole with an inch or two of water rising out of the bilge by the time help arrived. His boat would have sunk without the rescue boat's pump.

While the lifeguard boat crew handled the pump, John wrapped towels around the stern tube and propeller shaft and secured them with rope, which slowed the gusher down to a manageable leak. Once the large water pump emptied the bilge, Stronghold’s own bilge pump was able to keep up with the leak.

The LA lifeguards stayed alonside John’s boat as he sailed back home. When they neared Long Beach, the LA crew turned the rescue monitoring over to Long Beach lifeguards, who accompanied Stronghold back to the Alamitos Bay channel entrance.

At that point, John assured them he was doing okay and sailed the rest of the way back to his slip unaccompanied.

A cell phone call during the sail home had a diver waiting at his slip with four toilet bowl gasket rings. John said the diver used two of them, jamming the wax into the cutless bearing that supported the prop shaft in the stern tube. The wax reduced the leak to an occasional drip. Just to make sure, John made several trips to the boat that evening to check.

He said the LA lifeguard told him about the toilet bowl wax trick, noting that it could be done with an overboard dive on the prop shaft no matter how far from shore a skipper was.

With the bi-annual Transpac race starting, John couldn’t help but speculate, “What if that had happened to me half-way to Hawaii. I’d have lost the boat.” As it was, he considered himself very lucky not to have lost the boat anyway.

Monday morning he nudged Stronghold with his dinghy to the boatyard across the channel from our slips, while I steered the wounded vessel. Once lifted out of the water, inspection revealed that the stuffing box had seized on a corroded prop shaft and twisted the heavy reinforced hose, ripping it apart.

Later Monday I headed for the hardware store to buy a toilet bowl gasket ring. $1.79 seemed little enough to pay for something I don’t ever expect to need.

After all, my own prop shaft was replaced earlier this year after 39 years of service, along with new shaft packing in the stuffing box, new hose joining the stuffing box to the stern tube and new, extra-heavy-duty hose clamps. On the other hand, maybe the wax could also seal a crack in the hull if I were ever to hit something in the water.

I think that part of being safe at sea is recognizing a lesson to be learned when it shows up next door.