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Sea Savvy

What the eel revealed andother tales from the bottom

Even the most vigilant boater is eventually going to run into a surprise below the waterline

What the eel revealed andother tales from the bottom

Even the most vigilant boater is eventually going to run into a surprise below the waterline

“How do you know it isn’t a snake?” Mel asked me. I was asking myself the same question.

“I thought I saw a fin along his back,” she said.

I thought I saw? I said to myself. It looked like a snake to me. And it felt like a snake. But so do eels, although I didn’t know for sure because I don’t make a habit of feeling either.

It hadn’t exactly offered me a chance to study it when it first appeared in my engine room, and it sure as heck wasn’t trying to be overly conspicuous now. It had first appeared as I removed the top from my raw-water strainer. I do this regularly to check the basket for weeds and debris, but this time I was doing it because I had detected a reduced flow of water coming out the exhaust. On our boat the sound of a reduced flow is easily noticed, and we’re always on the alert for that as well as other sounds.

This day we were exercising the engine at a dock, and we’d heard a slight change in the exhaust water and immediately shut down the engine. Usually a reduced flow means a restriction in the intake, a restricted sea strainer, or that curse of curses, a deteriorating water pump impeller. I always check the easiest alternative first, and that’s the sea strainer just inside the engine room door. I opened the top and out popped the snake. Or eel. Or whatever the heck it was. It wasn’t a very big guy, but it was big enough to bite and do some damage if it were so inclined and so enabled.

As I was considering the alternatives, I was also thinking that there are many things that’ll bite on a boat, especially below water. All the “good seaman” books spend lots of time talking about working your through-hull valves and “regularly maintaining” them. This is, of course, good advice, but it leaves out a critical part of the equation. There’s a lot that can happen down there, even if your through-hull valves are absolutely fine.

Now you see it, now you don’t

Take, for example, the head intake that some years ago would occasionally let water flood through in great profusion, and at other times let only a trickle pass through. Even though my head was a Raritan PH II, which I consider relatively bulletproof, I figured there was something wrong with the pumping mechanism, so I rebuilt it. Once again it pumped perfectly — until it stopped again. So I rebuilt it again. (They’re easy to rebuild, even when you’re really getting ticked off.)

I pumped, and water flowed again. I pumped again and nothing. Next I disconnected the hose from the head inlet and lowered it into a bucket below the waterline. Water flowed through. So it’s got to be the pump, I thought in growing dismay. But as I watched, the water stopped flowing. It was just like somebody had turned off a valve. Well then, it has to be something over the intake hole outside the boat, I concluded.

No problem. I like to jump into cold water and look up my head hole. I couldn’t see a thing, but I was prepared for that. I jabbed a screwdriver up there (carefully so I wouldn’t damage the hose) and moved it around. I felt no obstruction but figured there must have been something that I’d not felt and that my probing had taken care of it. I surfaced, dressed and went into the head to pump. It pumped fine. Ahh, sweet success. But later that day, during a period of pumping, the flow stopped again. I yanked the hose off the barb and lowered it to the deck — I didn’t care about a bucket this time — and only a trickle came out. Damn.

I went over the side again, this time armed not only with a screwdriver but also with a light (a Pelican underwater Recoil LED StealthLite) that has an exceptionally bright beam. I quietly swam up to the hole, shone the light in and looked. It looked exactly like a hole to me. I could see past the through-hull valve and to the point where the hose turned — clear as could be. And then I couldn’t. Before my eyes, the hole closed. Figuring that my brain was oxygen deprived (more so than usual) I surfaced, floated around breathing, and headed down again. The hole was open again. But as I peered into the murk, it slowly closed. Then I saw it.

A small bivalve had attached to the wall of the through-hull. It was very difficult to see or feel when closed, but when it wanted to eat, when it sensed water flowing past, it opened. And when it did, because of the way it had grown, it almost perfectly closed off the hole. I don’t know who had been having a worse time, the bivalve or me. But it very soon had no further worries, except maybe convincing St. Peter that bivalves from head holes have a place in heaven.

You never know what the bottom is hiding, and there’s a whole lot of bottom to most boats. There are many other gremlins that can cause problems, gremlins that may manifest as things or situations. But the more you know, the more likely you’ll be able to figure things out.

Back to the eel

So I was trying to figure out how the eel stopped up and popped out of my sea strainer. The water doesn’t enter this type of sea strainer through a big hole; it enters through a somewhat narrow aperture under the rim. I assume this makes it flow relatively evenly into the basket. As best as I could tell, in that split-second epiphany, the creature had become wedged in this elongated orifice and thus was able to restrict the incoming flow of engine cooling water. But as soon as he saw the light of day — well, the light of my engine room, which is a far cry from the light of day — he made his escape. True, he just slithered, but it was so fast it could have put to shame the leap of the bionic woman.

Now, to get from my engine sea strainer to my bilge, you have to first cross the space between the engine room bulkheads and the engine stringers, and then get over the stringers. Once you are over the stringers, you’re down where no man — or woman — goes but where, I’ve come to believe over the years, many mysterious and sinister creatures live and thrive. It’s not a place where I like to stick my hand. When I shine a flashlight down there I pick one with dying batteries because I’m not sure I want to see what’s really there. Parts of it I couldn’t even reach with my hand anyway, which is very good, I suppose, because if I could reach into those parts I’d have a hard time fishing my hand back out of the hole after something bit it off.

I knew that if this creature got into my bilge, it would do one of two things. It would grow into something that could sneak out some night and eat us alive, or it would die down there in the warm spaces under the engine and start stinking. And stinking. And stinking. Neither thought was particularly appealing.

The good news was that the creature was still in the space outside of the stringers. It hadn’t figured a way to get over them yet. It wouldn’t take him long — it wouldn’t be a hard thing to do — but his main thought, I suppose, was to stay out of my sight until he figured it out and got the chance. To make matters worse (for me) and easier (for him), there are various pipes and hoses down in that space outboard of the stringers. They make great hiding spaces if you’re a snake. Or an eel. Or a wire tie. Or a screwdriver. Or the one and only nut that fits a critical bolt. And to make it worse, this space had several inches of water in it from the open strainer. The drain hole into the bilge had plugged with a piece of electrical tape I’d probably dropped in there, and under the circumstances I didn’t think it would be a good idea to unplug it to give the creature an easier escape. So I chose my weapon and commenced a campaign to hunt and capture the intruder.

I have several methods for dealing with my bilge, in addition to flight. I have four different types of “grabbers,” including two of the metal spring type with opening and closing metal claws. These were my first choice. I grabbed one and, with a flashlight, started looking. Sure enough, behind some hoses in the forward end of the engine room, I saw a coil that wasn’t supposed to be there. It was muscle and meat, and since it was moving I knew it wasn’t a part of the sandwich I’d had for lunch.

I carefully positioned the grabber over the coil, swiftly moved it down and let go the plunger. The claws grabbed around the slippery creature, which did just that — slipped away. It skillfully slithered back to the aft end where Mel was waiting with another pair of grabbers. She met with the same lack of success. This went on over and over again, neither of us knowing for sure what we were grabbing because it was moving so fast through the now murky water and doing such a good job of hiding under hoses.

I finally got the claws of my grabber around its middle part and, holding the plunger forcefully out, kept the claws clamped so tight that I was able to pull the creature from the shadows and hold him up. At this point we figured, much to our relief, that it looked like an eel, though not a particularly happy eel. He was wiggling, he was writhing, and he was slipping.

“Get a bucket, quick,” I said. The nearest bucket was up on deck, so Mel headed for the nearest trash can. But the creature wriggled free before she could return. This time he headed straight for the lowest part of the stringer, at the aft end, and I knew it wouldn’t be long before he wriggled over into safety, and the cause (and the eel) would be lost.

We both instinctively grabbed the two cotton rags I had nearby and lunged. Mel threw down her rag and covered the eel, and I swooped in with my rag in hand and grabbed the thing, throwing the whole mess into the trash can. There, we were able to get a good look and confirm that it was, indeed, just an eel. An eel, however, that would have smelled royally when it died. Rot reeks in more ways than one, and there’s more than dead eels that can rot.

Hoses aren’t forever

Watching that eel slither among the hoses reminded me of another type of problem from the depths. There’s always the old collapsed wall catastrophe. This has nothing to do with ancient China and the invading barbarians; it has to do with hoses and your sanity.

There are many different types and brands of hoses that deliver water to or from your boat through the hull (and also to different parts of your boat). Some of the obvious examples are the hose that brings cooling water to your engine’s heat exchanger (the eel’s home), the hose that conducts the warmed sea water and exhaust out the stern, hoses that circulate raw water and antifreeze water around the engines, hoses that drain the sink when you brush your teeth, and hoses that drain the cockpit overboard when it rains.

Most hoses are built to certain standards, including fuel lines, exhaust hoses and hoses below the waterline that are connected to the sea. Many hoses should be rated for use under high temperatures. And some have inserts or ridges of one type or another to prevent kinking when they are bent. Much depends on the use of the hose. But sometimes when a hose is replaced, the owner or yard person looks for a piece that’s of the right diameter and length rather than considering all the other hose criteria. And more often, the hose simply isn’t ever replaced until it’s leaking. You see it there and it looks all right, so if it ain’t broke you don’t fix it.

Most hoses used on a boat are composed of layers of material. Cut one and you’ll see. With age or a lot of bending and/or heat, sometimes the inner hose wall will separate from the rest of the hose. The separation may occur far down the line, where you’ll never see it, or it may occur close enough to the end so that a light can reveal it. But in many cases, the separation comes and goes. For example, the rate of the water flow may make the difference. And this can either completely or partially stop up the hose.

This is a difficult problem because you’ll probably have intermittent blockage, and if you look in or run a fish tape down the hose, all may look and feel normal. If you’re getting a blockage and the normal quick solutions don’t work, such as compressed air or a fish tape, then consider replacing the hose before blowing up the boat. Old hoses should be replaced as regular maintenance anyway. But this problem is relatively easy. It’s inside the hull. Outside the hull, the night can be much darker, even if you think you’re doing it all “right.”

Line cutters

Another surprise from the bottom will often come as an indirect consequence of hauling. Many of us use a line cutter on the prop. To me, it’s an indispensable part of my rig, and I’ve used Spurs for years and been very happy with them. We know we have to be hauled periodically, and afterward it’s good practice to check engine alignment. Line cutters must be installed and aligned according to manufacturer specifications to work well, and typically one blade has to be held stationary by an attachment that is fixed to the strut while another turns with the shaft.

When someone pushes the shaft back to check alignment, this could dislodge the stationary blade from the anchoring mechanism. Spurs recommends you tell the person doing the alignment that there is a line cutter attached, and that he secure the two components together with something like a rubber band before the alignment work begins (it will break easily and fall away when the job is done). Then make a mark on the shaft inside the boat so the shaft is bolted back in its original position and there is less likelihood of dislodging the line cutter. A quick dive and check of the prop and strut after the alignment will reveal whether there’s been a problem.

Yet another bottom surprise comes in the form of monofilament. There must be enough clearance to keep the blades from contacting each other with the boat’s normal structure flex under power. An engine will move forward or aft slightly, although probably imperceptibly, on its engine mounts when under heavy power. Usually line cutters such as Spurs will handle monofilament, but a particularly light test monofilament could be thin enough to slip between the blades.

Monofilament can do a lot of damage to your cutless bearing if it’s drawn in while the shaft is spinning. Cutlass bearings typically have grooved rubber inserts between the wall of the bearing and the shaft. These can be cut and greatly impaired by monofilament, resulting in a host of problems such as shaft wobble, vibration and transmission damage. The only repair is to haul the boat and replace the bearing. Anytime you think you might have run through some of this fishing line it’s a good idea to check, and routine checks may save a lot of trouble.

Cave diving

Another source of trouble from the deep comes from the opposite end of the boat. As I watched that eel try to dive down the hole, I recalled seeing an eel in my bow thruster tunnel during one dive. He didn’t seem particularly happy to see me.

We all know it’s theoretically a good idea to install a shield over the tunnel on each side of the hull. Sucking in a bag, a stick or even a large fish can quickly burn up an electric thruster motor or cause other serious damage. But most boats I’ve seen don’t have a shield. Some say a shield can interfere with the flow of water in and out of the tunnel and thereby impair the efficiency of the thruster. I won’t get into that debate, but I do know it’s helpful to be able to get tools into the tunnel, whether you have a shield or not, and to inspect it regularly.

Often when I look into mine during warm months I find that a very ticked off crab has made the tunnel its home. They love to hide behind the propeller and gearbox, where they reach out and get you. A big crab can crush right through even tough gloves with its claws. Usually they go (hopefully in the other direction) when I poke at them with a screwdriver. Once a huge Jimmy wouldn’t leave, so I had to climb back aboard, reconnect the power to the thruster, and hit the button. When I did, it sounded like I was grinding up half of New York City, but the crab got the message, even though he had only the briefest of seconds to reflect upon it.

Barnacles growing on the walls of a thruster tunnel, on the gearbox or on the blades can do an amazing job of negating the thrust. I’ve found that a group of barnacles anywhere in the tunnel will impair thruster efficiency much more than the same number and size on or near your propulsion prop or anywhere else on the hull will impair the efficiency of your propulsion engine. This is because part of what makes a thruster work well is the close tolerances between the blades and the tunnel wall, and the jet effect caused by the smooth walls and the tunnel.

Obviously, good bottom paint in this area is critical, but even so, barnacles seem to have a knack for finding and clinging to those few spots where debris in the water has chipped off the paint. So checking and cleaning your thruster tunnel can be very important, particularly toward the end of the season. You never know what you might find. (It can be dangerous to work around the boat’s propellers and the thruster unless all sources of ignition and/or power are disconnected so that there can be no starts.)

Strained sense of security

Boats being boats, even though you think you’ve got things under control, you seldom do — especially on the wet side. As the eel was slithering around in the bilge, problems like these were slithering around in the back of my brain. And a question kept gnawing at my gray matter. How did the thing get into the raw-water strainer? First, it would have had to get into the intake hole for the engine’s raw water cooling. This is covered with an exterior clam shell strainer, and that eel couldn’t possibly have gotten between its cracks. But it had. There’s no other way. There’s always the possibility that the strainer could be damaged, but not on this boat. I dive the bottom regularly. There was only one answer.

I’m no eel expert, but I do know that it was eel season at the time, and that eel boats were coming up into the creeks to set their traps and catch them. This means eels are active down under, and that there are plenty of them. So I think this one had to have gotten through the crack when it was much smaller and then grown. Somehow, when I’d been running the engine before, it had been able to hold on. I guess as it got larger, holding on against the stream of water became more difficult and it was washed along until it lodged in the orifice at the rim of the inside sea strainer. It wasn’t very big yet, so I assume it hadn’t been in there for too long. I asked an eel fisherman how fast they grew. He looked at me for a long time but never answered.

I guess he just didn’t understand that I was realizing how little you can take for granted on a boat. In this case, a component — the exterior through-hull strainer — is supposed to be giving you peace of mind. Every intake (and some prefer the outflows) should have one. Usually these are of the clam shell type with slits in them or of a round or sloped configuration with many small holes. All of these keep out the big things but not necessarily the little things. Like our baby eel. And if these little things get inside and grow, so can your problems. Little things can include barnacles, some bivalves (very unlikely) and vegetation. Because of the lack of water circulation inside the strainers and the lack of light, there’s less likely to be growth in these spaces, but it does happen.

The best protection here is to remove strainers when the boat is hauled and paint under them. However, if these are screwed into the fiberglass you can only unscrew them so many times before the glass crumbles, necessitating repair. And an effective water barrier must be used to prevent migration into the screw holes and blistering. Also, some of these strainers are integral to the through-hull fitting itself.

My preference is strainers with removable covers. Unless you can efficiently remove the strainer or its cover, getting as much paint to the surfaces inside as possible by spraying or even using a tiny brush — even a cotton swab — may be the best way to go.

It’s also important to not have the attitude that an annual haulout is all you need. Most boats should have bottom checks regularly by a good diver, even if they have a good coat of paint applied every spring. Have a diver go down, look around and shine a light into the strainers to see what, if anything, is lurking back there. If something is growing, usually it can be carefully “dismantled” with an ice pick or other small tool.

Worrying me more than the growth rate of eels was the reminder that I’ve got a lot of other raw-water holes under my hull, and therein lie all sorts of possibilities — if not for eels then for trouble. The day before I began writing this I spent an hour and a half under water, using my Brownie’s Third Lung hookah, checking out the bottom of my boat and cleaning up problem areas. The sea strainer was in fine shape, and the eels had already headed for warmer water, as had the crabs. All was peaceful and in order. But I couldn’t help but muse: Who knows what terrors of the deep are lurking there to ruin my day, down where the sun never shines.

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