I’ve been amazed over the years by boat problems caused by the tiniest of things. I know about the big things — the bottom falling out, the engine quitting in the middle of the inlet, the mast coming down. We know these things are happening when they do, and we know it’s going to be a big deal. In a way, it’s less frightening. “Oh, well, my oil pan just dropped out of my engine.”

It’s not a good thing, but you know you’re in for a bad time, so it’s not going to be quite so bad. But there are a billion (yes, count them) little things that can go wrong on a boat and ruin your day more surprisingly. Here are some that have reached up and grabbed me over the years.

Get set

Take the tiny little set screw. When’s the last time that you tightened one? Unless you’ve tightened a lot of them recently, you may be in for a problem. Some set screws are relatively large and obvious, such as the ones holding your prop shaft in the coupling. Generally you tighten these with a wrench, and that’s easy enough. Sometimes there’s a hole through the screw head, and stainless steel wire that purports to keep them from backing out over years of vibration. Don’t count on it. When that set screw loosens, the next time you throw her into reverse, the only thing that may back up is the shaft and prop … back up and out.

Your boat probably has much smaller and more insidious set screws. And to make matters worse, you probably have to tighten them with a tiny Allen wrench. We all carry tiny Allen wrenches around in our pockets, don’t we? Not only is it a pain to find an Allen wrench that actually fits — and it may be metric or standard, of course — but we’ve got to think about doing it in the first place. Not only are these set screws small, but they’re also usually recessed into whatever they’re “setting.”

I recently noticed that several had backed out of my pushpit. They were supposed to be holding the rail to the stanchions. They weren’t, and I was very lucky to have noticed them — well, my wife, Mel, “brought them to my attention” — before someone went overboard.

You can probably find these “tingums” all over your boat. And they’re all prone to vibrating loose — unless they’ve corroded, which is a whole ’nother problem. Among the neat issues these little things can cause when loose are failure of a boat to speed up or slow down or reverse, failure of a steering wheel to steer, the slipping out of a woodruff key, thereby enabling a wheel (maybe a water pump pulley) to spin until the engine overheats and it has ground out the interior of its hub. I could go on and on.

Lost keys

And that reminds me of those tiny little keys that aren’t your car or house keys. Failure of a woodruff key or square key means all of the above and maybe more. Usually it fails because of years of running and slight wear, which can escalate quickly. In the meantime, the bits are damaging the seat.

When you find a key that’s in trouble, you’ve got to replace it, which means you’ve got to have one that fits. And although I really don’t know, I imagine there must be thousands of fits. Or maybe “misfits” is the better word. If it’s a woodruff key, you’ve got to get its rounded bottom into the rounded slot and perfectly aligned with the shaft, then get the pulley — or perhaps the raw water pump impeller — on it without pushing that round-bottom key out, at which point it’ll drop into the bilge and disappear forever. Carry lots of keys of all types and learn that some applications — for example, certain rubber impeller-driven raw water pumps — require using a workbench, not the tiny space around your engine.

If you’ve never replaced a key, maybe you’ve wrestled with a circlip. They are on all sorts of shafts, demurely seated into a little cut groove, and doing the job, we hope, of holding a washer or some other component in place, which in turn keeps the wheel or pulley or gear from spinning off. You usually can’t see them because they’re covered with grease or grime. When you do, after spending an hour or so trying to get that washer out — which was impossible because it was held in by a circlip — you realize that you don’t have any circlip tools that will fit the little holes in the end, much less reach them.

So you resort to other tools, such as two ice picks. These are getting very hard to find, I suppose because certain types think that somebody could hurt somebody else with them. But when I find them I buy several because I know about circlips and about my circlip tool that will never fit. The real problem comes when you start working them free of the groove. They are, in part, springs. They have a tendency to take off and, being very small, fly invisibly to a part of the boat you’ve never seen.

My daughter was rebuilding a small gas engine in the main saloon on our 47-foot motorsailer as part of her home schooling. We’d begun the job on the aft deck, but it was almost Christmas. We were in the Bahamas, and it was very blustery and chilly. A circlip for a valve stem took off, and we looked for it for hours, in vain. We couldn’t complete the job without it, and you don’t just go off to a circlip store from your remote anchorage in the Out Islands. We had to give up and get on with Christmas. A couple of weeks later, as we were taking down our Christmas tree (yes, we always had a real Christmas tree, even in the Bahamas), we found it hooked around a branch at the very top, just under the starfish.

Crying weep holes

Let’s leave the hard-core mechanical issues and go to something more esoteric, such as weep holes. These little things can cause immense problems if you don’t know they’re there and what they’re about. I became a weep hole aficionado when the wide sliding windows of my little prehistoric express cruiser kept leaking. There were little holes drilled through the window framing at the bottom of the window tracks. Sliding window tracks are notorious for accumulating junk, which in turn finds its way into the weep holes and stops them up. And then in comes the water with the next rain or sweep of spray. All it takes is the end of a wire coat hanger (they seem to be outlawing these, as well as ice picks) to ream it out.

And there may well be weep holes in other places on your boat. You might find one in an anchor windlass, a winch, the base of a mast, overhead hatches, underneath water-pump seals and many other places. They all have a reason for being there, and they all have a tendency to get stopped up. All you have to do is take out that deadly weapon, the straightened wire coat hanger, and go to it.

Suck it in, let it out

There’s also a little hole that’s the reverse of the weep hole. It’s called a vent tube. It’s a little tube that is supposed to allow air into your fuel tank as your engine pumps out the fuel or allow air to escape as you fill the tank. If air doesn’t get in, the flow of fuel is reduced, eventually starving the engine. And if air doesn’t get out as fuel is gushing in, the tank could do anything from burp fuel into your face to rupture from the interior pressure.

There’s also a vent tube for your water tank and your holding tank. (Aha, now we begin to understand the importance of this.) The tube itself isn’t necessarily tiny; unfortunately it can be rather long. But the hole through which it must suck or blow air is usually tiny. And it’s usually pointing down to prevent water from coming in, not to mention that it’s usually covered by a shield of some sort. And all it takes is a mud dauber or just about any other bug, not to mention random debris, to clog it.

How many of us make a regular habit of crawling around our boats on hands and knees looking under vent hole covers, perhaps having to hang over the side at the time, to see whether the hole is clear? If you didn’t raise your hand, you’re in good company. “But my vent holes have screens,” you might say. Most vent holes do, and if you find one that doesn’t, fix the problem. But even with screens, critters and crud can stop up a vent hole.

This is no joke

Speaking of stopping up, let’s consider another aspect of this issue. It’s called a joker valve. You may not have heard of joker valves, but odds are you depend on one or more aboard your boat. They let something flow through one way but not the other. Sometimes that something is air, as when you empty a piston in the head. Air has to get in as the waste water exits if you’ve got the intake closed in order to empty the bowl. So the joker valve opens up and lets air in. When the intake is open to fill the bowl with clean water, you don’t want that water to exit the little hole the air just entered. Your ever “smiling” joker valve handles it.

Perhaps of greater importance is the larger joker valve, which lets the waste and water out of the head but doesn’t let it back in after the pumping is finished. When either of these little valves fails, the results can be, well, unpleasant at best. If you know about these little things, you know they’re relatively inexpensive and that you can replace them yourself. They usually fail from clogging or because of material deterioration caused by aging or calcium deposits.

Those on the downstream side of pumps in heads have an especially tough job, and when they fail it can really ruin your day. They have to be thick enough and of a composite dense enough not to tear when they’re forced open, but not so dense as to remain closed when you need them to open. They also must be supple enough to let stuff out and then seal again to prevent backflowing. The base also has to serve as a gasket in some rather critical plumbing.

Raritan, a master of heads and other products, has developed a new generation of joker valves that master these issues. You may not know it, but those valves will be there smiling, opening and closing — another little thing helping you with your boating pleasure.

Also in the department of keeping liquids where they belong, let’s take a look at seals. You’ve got seals in many places on your boat, and each is important. Whether it’s water, transmission fluid, lube oil or whatever, there’s a little seal doing a job … you hope. Some are easy to replace, but others require special tools so you can press them in and out. They include simple packing (as in your stuffing box), perhaps your old engine’s oil seals and more esoteric little guys, such as a rubber U-cup with the edges held close to the shaft by a tiny stainless steel spring. If you know about them — and this includes the springs that can pop out when you replace them — you’ve maybe sealed the deal for the day.

Anti-siphon, anti-sink

Although your boat may not have any anti-siphon valves, many do. Their purpose is to keep water from siphoning in after you’ve been pumping it out. They’re typically found on the engine raw-water feed line if the engine is or may be below the waterline, on head hoses or on bilge pump plumbing. When your engine, head or bilge pump pushed water out through the discharge hose, it probably displaced all of the air in that hose. If the component is or may become below the waterline, the water flow could then reverse back into the boat.

There is usually a loop in the hose rising above the waterline, but often more than just the loop is required to keep water from running back aboard. The siphon effect causes the weight of the lower water to suck the seawater back in. The fix is simple: an anti-siphon valve at the top of the loop.

This arrangement is seldom a “little thing,” and it’s usually obvious if you know what to look for. But there must be an internal component that makes it work, and this is usually rather small. It’s often nothing more than a little joker valve. The lip is pointed down into the water flow. As water is pumped past, the closed lip keeps it from coming out of the top of the valve and into the boat. When the pump stops and gravity creates a suction, the lip opens and lets in air, breaking the vacuum and killing the siphon effect. It may be a tiny little part but it’s very important.

I had a brand-new, very expensive anti-siphon valve fail on a relatively new boat many years ago. Overnight, water siphoned in and filled up the cylinders of my engine. These little things, whether they’re joker valves, floats, spring-loaded stainless or whatever, all suffer wear or become clogged. Regular inspection and replacement, as needed, is critical.

Little black buttons

A very important little thing on your boat is the momentary switch. This deserves special consideration because it normally does so many things. It may blow your horn, flush your electric head, activate your anchor windlass, stop your engine or, more important, start it. Usually when, say, the engine won’t start or even make a sound, the first reaction is to start throwing money and time at the starter solenoid, the starter or lots of other expensive things that are also difficult to access. But quite often the problem is in that little black rubber-covered knob (or maybe it’s chrome-plated and not covered) that you just pushed — the momentary switch.

The basics of a momentary switch are fairly simple. The “button” is essentially a plunger that’s held in the out position within its casing by a spring. At the other end of the plunger (inside the switch housing) is a contact surface — usually a metal conductor attached to the plunger or pushed by the plunger so that it contacts (jumps) and, thus, connects the back ends of the two wire terminals. The circuit is completed, and the horn blows or the engine starts or the head starts its flush cycle. When you remove your finger, the spring pushes the plunger back out and the contact is broken. What can go wrong with this?

Each time you push that button and the contact points contact the circuit, there is arcing. Over time, this causes pitting or corrosion to the extent that the contacts pass no current or the current passed is inadequate to do the job well. The fix may be to simply sand or file the contacts. You must disconnect the wiring and remove the switch from the panel first and open the housing at that end of the switch. This might not be worth the effort, depending on the switch, but in an emergency you’ll be glad you know how to solve the problem at least temporarily.

Another type of problem is that the contact component shifts or becomes dislodged from its assembly and doesn’t firmly seat against the backside of the wire terminals when you push the button. This is usually caused by old age and wear, and is seldom worth fixing. (A well-made switch will typically last a long time before this happens.) A third issue can occur if there is an obstruction between the plunger and the shaft walls in which it moves. This could occur from problems such as too much lubricant that has hardened, from dirt or from corrosion.

Depending on your switch, this may be easy to access and clean using light emery paper or, perhaps, a rough, clean rag. This can be a particularly worrisome problem because often the plunger gets stuck in the down position, meaning the horn won’t stop blowing. And it’s far worse if the momentary switch starts an engine. I’ve seen these switches stick down in this application, causing the starter solenoid to remain activated, thus continuing to run the starter after the engine has fired. This can quickly ruin a very expensive starter and related components. This is a good reason to replace these relatively inexpensive switches regularly.

You can usually determine whether the switch is the culprit by carefully jumping the wires connected to the terminals behind the switch, but this can be dangerous because it may create a spark, not to mention shock. It’s best to disconnect the wires coming from the switch and use a volt/ohm meter to test for continuity between the two terminals on the back of the switch. There should be absolute continuity when you push the button. If there is no continuity or if it is intermittent, you’ve located the problem.

But volt/ohm meters are sometimes difficult to interpret unless you’re very familiar with them. Some mechanics use an improvised jumper wire, which is a short, well-insulated wire with terminals at each end and a positive on/off switch in the middle. You turn the wire switch off, connect the wire ends to the momentary switch terminals, turn the wire switch on, and this jumps the terminals. This wire and its on/off switch must be heavy-duty enough to safely conduct the current involved. (If you have any doubt, get a professional to do this simple check.) If the horn blows when you jump the wires, your issue is probably in the switch.

There are many variations of this type of switch, and yours may be different from what I’ve discussed here, but if you understand the principle, you can probably deal with the problem.

Let it slide

Many of us have push/pull cables enclosed in sheaths. They transfer motion from the helm station controls to such components as the throttle, transmission and kill switch. We know that the cable coming out of the sheath has to be checked for its connection at each end. If the connection fails — and all it may take is a little cotter pin — you may shift into reverse to stop the boat at the slip and keep powering forward.

But there’s another little thing in this scenario that we often overlook. The sheath inside which the cable travels must be anchored at each end so that the system works. These anchoring clamps often are exposed to weather, vibration and other hostilities. If they rust, break or vibrate loose, you may go through that pier instead of stopping neatly in place. Knowing where the clamps are and regularly checking them can save the day.

Every little thing’s gonna be all right

Apparently Bob Marley didn’t do much boating. But if you recognize the importance of all the little things on your boat, their jobs and how they work, it’ll go a long way toward making Marley’s mantra rule on board.

November 2014 issue