Boat Shop Sea Savvy When the you-know-what hits the fan
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When the you-know-what hits the fan

Even the soundest boats can suffer without proper and timely inspections in the smallest of places

Life is good as you cruise along on a beautiful day. Everything’s working right, running right, sounding right and feeling right. And then it hits the fan. What hits the fan? That’s the problem with a boat. It could be anything. And a lot of those things are gremlins that we haven’t even dreamed about, but have been lurking, hiding, waiting to pounce. Let’s take a look at just a few.

Joe and Mary (all names are changed to protect the victims) bought their dream trawler and, after a year or so of use, had it hauled for a simple paint job. Yard personnel scurried around checking out the bottom, the boat blocked into her resting place. From the stern came a low whistle. “Hey, man, look at this.”

“This” was the V strut supporting the shaft, the prop, and handling all the torque from that running gear. Some areas looked like it had been eaten by worms; some areas were completely gone, as though devoured by ants. But the strut was stainless, not sweet cake. The culprit had been stray electricity.

Close inspection revealed two likely causes. In the first instance, the stainless-steel strut, which must have looked beautiful when new, had been fabricated by welding machined components together. The heavy round tube through which the shaft ran (held in place by a cutless bearing) was stainless, and the surrounding strut component was stainless. The weld beads were for stainless.

But there is stainless, and there is stainless. It comes in different grades, ranging from essentially junk to very stable material. The material along the weld bead had seriously deteriorated. There was also deterioration in other sections of the strut, particularly around the area where the tube was in contact with the rest of the strut. In order to remove it, a yard man had to crawl inside beneath the cockpit and take off the nuts holding the bolts securing the strut.

Another low whistle filtered through the hull. “Hey, you oughta see this. Somebody forgot to attach the bonding wire to these bolts. That thing was totally unprotected.” The wire was attached to the through-hull rudder support nearby, but not to the strut. The combination of dissimilar metals in the weld bead and the parts welded, dissimilar metals in different sections of the fabricated strut, and lack of protective bonding had rendered the strut a disaster in the process of happening.

The owner reported he had felt some vibration. This problem had been developing, unseen and unsuspected, for some time. But at this stage, it wouldn’t have been long for a total failure to occur, resulting in the loss of the running gear, at least, and possibly in sinking.

Creeping crud

We have a tendency to think stainless is trouble-proof on a boat. Anytime we think that about anything on a boat, we’re asking for trouble. Take, for example, the apparently benign propeller shaft. They’re usually stainless. An owner should religiously perform regular maintenance on the shaft, which includes tightening the stuffing box so that a little water seeps past as the prop is turning, but not too much.

This much rust seeping from a hidden place probably needs some attention.Periodically the stuffing must be replaced altogether. This is easy enough to do even when the boat is in the water, if you know what you’re doing. When you back the stuffing cover off the assembly, it’s important to look at that section of the shaft that lives underneath. But it’s hard to do this as water rushes in, and many don’t even do it when changing stuffing while hauled.

Check to see that it’s smooth. If it isn’t, you may be feeling salt buildup … maybe. If you swipe at it with emery cloth and it doesn’t clean up, there’s more room for concern. It may be pitting from developing crevice corrosion. If it develops enough, the shaft will break, leaving you powerless with a large amount of water likely flooding in.

Crevice corrosion occurs in stainless when it’s in trapped, non-moving water, such as in stuffing boxes of many kinds. The only way to tell how deeply the crevice corrosion has developed in a shaft is to pull the shaft and have it X-rayed. At this point, it may make more sense financially to replace it altogether.

You don’t need oxygen-deprived water to have problems with stainless. I was hanging high above the deck from a main mast halyard one fine day, swinging around, checking things out. I do this often. By luck, I noticed (to my terror) that one of the stainless fittings to which a mainstay was attached had a crack in it. It wasn’t from corrosion. It was high and dry up in the air. It was a simple crack. It could have been from stress, poor-quality stainless, an inadvertent flaw in the manufacturing process, or other causes. Whatever the reason, it resided high above normal inspection levels, silently waiting to take my mast.

Stainless isn’t the only source of betrayal. We were once running a great little sailboat with a great little inboard. It never missed a lick until it rather suddenly began heating up one day. The exhaust water seemed diminished, so I shut down the engine and checked the impeller. It was fine. I restarted the engine, and the heating grew worse until I couldn’t continue running it.

The sea strainer was fine, as was the through-hull. There was no apparent problem. But this little engine was raw-water cooled. Many gasoline engines on boats still are. It isn’t a good idea, but it’s cheaper than adding heat exchanger, header tanks and other gear to allow freshwater cooling.

With a raw-water cooling, the passages inside the engine slowly become clogged through the years with stuff like burnt material from the water, salt accumulation and rust. The engine’s cooling tolerances don’t let you notice this at first, but it’s building. The accumulation eventually reaches a level, either throughout the engine or at some constricted place, where the flow of water is restricted to the point that it can no longer cool the engine.

Sometimes this happens in the block itself, but it often happens first at the injection nipple, where the raw water is injected into the exhaust. The nipple can even cause overheating damage on a freshwater cooled engine. After the raw water passes through the heat exchanger it goes into that injection nipple, where it mixes with and cools the exhaust. But through the years the nipple and the passageways downstream in the mixing elbow become clogged with rust.

Even if the apparatus is stainless, it may become clogged with debris or a buildup of organic matter that’s in the water cooked to a crisp and plastered to the walls by the heat of the exhaust. And fairly suddenly, your day on the water comes to a lousy end. It’s not just a matter of an overheating engine. This can also result in burning out the exhaust hose, letting exhaust and/or water into the boat.

Machinery gremlins

The engine space is full of lurking disasters waiting to happen. Vibration and chafe are potential killers of the best equipment, and there is plenty of both in an engine room. I once witnessed a sailboat docking with a skilled helmsman at the wheel and crew standing ready to secure lines and “do it right.” They were looking forward to hot showers, a good meal in a restaurant, and rest. They deserved all this and more because they had just brought the boat up to North Carolina from the British Virgin Islands, and the trip had been perfect.

They were docking with a lot of current running with them into the slip, because this was the only slip available. When you must do this with a single-screw sailboat, you often must come in at high rpm to have enough speed to maintain steerage. Just before you get to the point where the boat must stop, you put it in reverse and back down hard with full throttle. The skipper did this perfectly, but the boat didn’t back down. Instead, it leaped forward, picking up speed and power.

As the deck hands scrambled aft, the boat rammed into the dock, smashing through water line, electrical conduit and wire. It then mightily pushed the trashed dock into the boat sitting in the opposite slip. The skipper of that boat had been calmly watching the expert docking job from his “safe” vantage point. He sat in stunned silence, probably ready to buy a condo in the mountains.

The poor guy at the wheel of the offending sailboat just stood there, also stunned. His crew hadn’t been able to do anything but run aft to save themselves. Finally, amid the arcing of wires, spraying of water and with people running in all directions, someone went below to look. Sometime during the voyage a cotter pin had slipped out of a small hole in a pin that connected the shift linkage with the transmission. When the skipper shifted, the transmission didn’t know it and remained in forward as he throttled up, thinking he was putting on the brakes in reverse.

There are many other vulnerable areas like this in the linkage for the transmission and the throttle, including the mechanisms that hold the linkage in place. Even if the transmission gets the message, if the set screw securing the shaft into the coupling has vibrated loose, as they sometimes do, the shaft may spin right out when it goes into reverse, jamming the rudder or maybe clearing the rudder, leaving a nice hole into which water gleefully floods. I try to check this every day I’m under way.

Another seemingly benign, but potentially dangerous, engine room gremlin lies with the non-moving, high-pressure fuel pipes running from the injection pump to the injectors on many diesels. Although they seem completely static as you look at them, they are all vibrating to some extent as the engine runs. (The entire engine is vibrating.) These are usually anchored in place with various clamps designed to do just this job.

But when mechanics pull an injector or do something else in the neighborhood of the pipes, they often leave something loose, or it may just work loose over time. It may be a clamp intended to hold the high-pressure pipe in place, or another part of the engine that vibrates against the pipe — the result can be the same. With enough time, the high-pressure pipe may be breached, and diesel will spray into the engine space, often in a fine, explosive mist. If this contacts a red-hot exhaust manifold or any of the many other sources of combustion, the engine space can quickly become fully engulfed in fire.

Electrical lapse

A more obvious lurking engine room culprit is wiring. Any hot DC wiring (or AC) that has slipped from its constraints and is lying against any part of the engine or generator will, if left long enough, likely suffer insulation abrasion that results in dead short arcing with enough heat to melt metal, not to mention start fires and destroy electronics and a whole host of other things. All it takes is the mere touching of wire to vibrating metal for a long enough period of time.

And then there are the batteries. Buying and charging batteries is not a place to scrimp, but many do. Boat batteries lead a tough life. They are stored away out of sight and out of mind as though they are harmless objects to be replaced every few years. Also, they often become deeply discharged and need to be fully charged, not just a superficial surface charge, within a relatively short period of time. This means chargers, whether alternators or generator-powered battery chargers, and their regulators must be fit for the job.

There are many good units available, but even the best will sometimes malfunction. We all know what too little juice going into the batteries means. It means that embarrassing call so often heard on the weekends for a towboat because “my radio won’t run and my motor won’t start.” But too much charging can also cause problems, such as gassing and overheating, possibly to the extent that the heat causes not only gassing but a meltdown or short between cells.

The myth of “maintenance free” batteries has lulled many a mariner into thinking he doesn’t need to worry about problems in this part of his realm. But even a maintenance-free battery can emit gas or explode if it’s overcharged. An interesting thing about battery gas is it’s very corrosive. If you see deteriorating cloth, wood or other material around your batteries, you know you’ve got a problem that needs to be addressed immediately. Over time, the corrosive effects can be severe, and the gas is indicative of other problems, which may be from the charging equipment or the battery itself.

We protect ourselves on Chez Nous by using what we consider to be very high-end equipment. We use heavy-duty Rolls (Surrette) 8D and 4D modular batteries. The individual cells are loaded into place and bolted together. This enables us to get more battery aboard without hiring a couple gorillas. These batteries also have Hydrocaps, which are said to help recombine escaping gas and return it to the battery. We also use sophisticated Xantrex chargers, with which I have been very happy for many years.

Batteries may also contribute to another frequent hidden failure. Most boats have at least several solenoid switches. They do many jobs for us. They’re great little machines that are often taken for granted. Some just move a lever to perform a job or open or close a valve. But many function as electrical switches that enable a small amount of current running from a low-amperage button at the steering station to close and open a heavy-duty switch that controls high-amperage current in some other part of the boat. Solenoid switches activate and engage the engine starter, and are also used to activate anchor windlasses, electric winches and dinghy lifts.

You just push that little black-rubber-covered button, and you get a nice result. What’s really going on is that when you push the button you supply current to the solenoid, which energizes a coil creating a magnet. This typically pulls a shaft from one position to another.

In a solenoid that’s serving as an electrical switch, the shaft typically pushes a button and creates a contact through which a large amount of electricity can flow. The button usually is held in the off position by a spring. A washer-shaped piece of metal is attached to and behind the button. When the solenoid shaft hits the button pushing it back against the spring, the washer contacts two metal strips to which wires are attached. Bingo! You have a connection that high amperage electricity can flow through to do a job.

But every time the solenoid is activated and contact is made, an arc of electricity occurs. Every time the arc occurs, it causes a little carbon formation where the contact is made, and a little pitting eventually occurs. As the solenoid continues to do its job over the years, the carbonization and pitting worsens more rapidly. Low voltage in the batteries can speed up this process.

But the skipper sits up at the wheel just pushing that rubber-covered button on the console whenever he wants the job done, never thinking about what’s going on in that small cylinder or box called a solenoid switch. That is, until it makes no contact at all and the job doesn’t get done. Or it hangs up, supplying electricity not just until the job is done but until the thing doing the job, like a starter or windlass, is destroyed. And sometimes, particularly when the solenoid has been subjected repeatedly to improper voltage, the coil may burn out and heat up dangerously.

Don’t get hosed

But enough about electricity. Let’s take a look at something really benign — like hoses. Your boat has many of them, unless you’re smart enough to be happy with a system-free skiff. Hoses just sit there. What harm can they possibly do?

Hoses of all types were offloaded from Chez Nous, replaced by numerous rolls of Rescue Tape.While they’re sitting there, they are slowly rotting. Symptoms of this include rigidity at first and good, old-fashioned leaking at the end. They may have wire embedded within the hose fabric that provides rigidity to prevent collapses, as when the hose is used for suction. But as time passes, this wire rusts and sometimes perforates the hose wall, either inside or outside, causing quicker rusting of the rest of the wire, leaks and collapse. But looking at that hose sitting there, it’s easy to think that nothing could be happening.

Then there’s the stumper that’s driven many a poor boater nuts: water stops flowing through the hose. Sometimes. Or it may not stop, but just slows down. You look at the through-hull, and it’s clear. The sea strainer is clear. You pull the hose off its barbs and look into each end, and all you see is the inside of the hose. And it’s clear. You put it back on, and all goes well for a while, and then your engine overheats or your sink won’t drain or whatever. The hose is stopped up again. How can a hose do that?

I call it “ballooning.” Most hoses are made with at least several layers of material. It isn’t unusual for the inside layer to become perforated and leak a little. This is much more likely to happen to old hoses, but it can happen to new ones. It can be caused by such things as bending the hose too much, the breaking of a wire insert, or faulty construction. When it happens, water flowing past the breach in the inner wall may get between that inner wall and the outer layers, causing the inner layer to balloon and create an obstruction. But when you pull the hose off and look through it, the balloon will be collapsed, and you probably won’t see it.

The best way to avoid this problem is to use the right hose for the job, replace hoses regularly, and inspect them frequently. And there’s a very interesting solution for many leaking hose problems. I used to carry approximately 75 pounds of spare hose of all sorts on board. Last fall I offloaded most of them, freeing up a huge storage space. I took aboard numerous rolls of Rescue Tape, marketed by Harbor Products. It’s a silicone tape and, from what I’ve observed, it’s far better than electrical or duct tape for repairing leaking hoses, even when there’s significant pressure and heat involved.

Simple Simon

Let’s leave all these complex issues and look at the simple life. There are boats that have far fewer systems than many I’ve talked about here. Take the sailboat. It may not even have an engine. We’ve already talked about rigging problems. That’s a no-brainer. What about the nice centerboard that swings down, giving the boat more stability and vastly improving sailing performance. It is pivoting around a pin that passes through a hole with a bushing of some sort in the top corner of the centerboard. The bushing in the pivot hole and the centerboard material around the hole take a huge amount of abuse through the years. Given enough use, the section of centerboard containing the hole may break, allowing the board to drop out of the boat, dangling by its lanyard.

This happened to us once during a beautiful, boisterous sail downwind on Chesapeake Bay. The stainless lanyard holding the centerboard didn’t break, and we motored in, rolling gunwale to gunwale with the board hitting the hull on each roll like a doomsday bell.

If the centerboard is a drop-down-style that you lower in the well, you may still have problems. The well will sometimes fail where it joins the hull. You may not notice it at first because the failure may occur as delamination within the fiberglass joint. But a sudden stress, as when you get a nice gust while sailing, can cause catastrophic failure.

And then there’s that simple tiller on that simple little sailboat. No worries about stainless cable coming off pulley wheels in inaccessible, invisible places. No worries about pulley wheels pulling off the bulkhead to which they’re attached. Just grab that stick and sail. Which is what I was doing on one small sailboat, leaning way out as 20 knots of wind rushed over the port quarter, giving us a beautiful ride. Until the stick broke. It was wood, and it was old.

Wood can crack and splinter little by little until it finally lets go. This was a very nice laminated tiller, but it let go at just the wrong time, leaving the boat out of control and me hanging on for dear life to keep from going over. Wood fatigues like everything else, particularly when stressed like on a tiller.

There’s another little problem with wood, found sometimes on poorly constructed sailboats as well as many similarly constructed powerboats, large and small. On many boats, the hull and decking structure is supported and strengthened by wood that is fiberglassed to the hull and deck — for example, bulkheads, cabinetry or dedicated stringers behind interior structures. This is a tried-and-true method of boatbuilding and can be quite effective. But as the hull works and the boat flexes, the bond between the wood support and the hull can come apart. The cause may be poorly applied glass, applying it under adverse conditions or to surfaces not properly prepared, or simply because the hull is so thin that this method isn’t adequate. It may also be caused when the wood rots from uncorrected leaks.

Sometimes a little creaking will give you warning. Sometimes it takes years for the problem to develop. Sometimes it develops with relatively new boats. You often don’t know this is happening because the bonding is behind an interior structure. But when it starts to happen, that boat can very quickly become dangerous to use.

There’s another surprising problem with wood that can ruin your day on even a simple outboard skiff. These boats are often built with a wood transom encapsulated in fiberglass. This has proven to be an effective method of boatbuilding for many years. But an outboard applies huge stress to the transom. As you rev up the engine, it has a tendency to pull the transom back from the top. This is why a well-built boat has abundant support structure in the stern.

However, after many exhilarating times of getting ’er up on plane over the years (sometimes much earlier with poorly built boats), the transom fiberglass begins to develop cracks. These may be only in the gelcoat and of little consequence, but they may migrate through the glass, allowing water to reach the wooden core. This process is helped along by someone drilling a hole through the transom to mount a transducer or outboard and not properly sealing it. I’ve seen transoms literally peel back, with the outboard going under. Careful attention to this area, even on the most simple outboard skiff, is important.

*     *     *

Yes, sometimes it seems that a boat is like a huge fan, just begging for stuff to hit it. But I like some wind in my face, even if it sometimes comes with unexpected ingredients. And that’s a basic ingredient of boating.

Tom Neale is technical editor for Soundings and lives aboard a Gulfstar 53 motorsailer. You can buy his book, “All in the Same Boat,” at


This article originally appeared in the June 2009 issue.