Spooky Boat Problems!
October 31, 2023 6 min read
Navigation lights turning off or on by themselves. Water collecting out of nowhere in the bilge. Engines suddenly going into limp mode after hundreds of hours of trouble-free service. Unexplained listing to one side or the other when on plane. Random whiffs of gasoline vapors in the anchor lockers. If you didn’t know better, you might wonder if your boat was … you know, possessed. And really, who’s to say it isn’t?
Contents
Just in time for spooky season, here are some of the more mysterious boat problems you’re likely to face along with suggestions about how to banish them for good.
Electrical Gremlins
Boat electrical systems seem to be particularly vulnerable to seemingly paranormal problems. Your courtesy lights might only turn on when the bait pump is also switched on. Your trailer brake lights might go out on bumpy roads. Your chartplotter might suddenly shut itself down for no discernible reason.
If you’re trying to pin down a slippery electrical gremlin, keep the following in mind:
It’s always a grounding issue (almost).
Grounding problems can create all kinds of weird symptoms and are the most common cause of problems with simple 12V electrical devices. Start by making sure that whatever device isn’t working has a clean ground.
Clean your battery terminals.
With widespread electrical problems, bad connections at your battery terminals are often the culprit. These issues can be intermittent too. Before digging too deeply into anything else, use a wire brush to clean your terminals and make sure terminals are tightened securely. Terminal nuts backing off from vibration are a common cause of sudden no-start emergencies.
With widespread electrical problems, bad connections at your battery terminals are often the culprit.
Check your voltage.
If your electronics suddenly turn off for no apparent reason, check the voltage they’re getting. Many newer electronics have high and low voltage thresholds and will shut themselves down if voltage isn’t within the acceptable range.
Check the switch and panel.
Boat rocker switches last a long time, but they do fail, so don’t rule out a bad switch if everything else checks out. Also, the wiring on the back of switch panels sometimes comes loose. The switches in a typical switch panel are wired together with a complex (at least to most of us) pattern of jumpers. If one wire falls or is accidentally pulled loose from the blade terminal on the back of a switch, it can cause weird symptoms that extend beyond that particular circuit.
Mysterious Bilge Water
Water accumulates in bilges normally from a variety of sources — small leaks in below-waterline plumbing, rainwater or spray finding its way through holders, cup holders or other openings into the bilge, drainage from ski lockers, etc. But when you start seeing more than a normal amount, tracking down the source can be vexing. Here are a few things to keep in mind:
Sometimes built-in transom livewells aren’t completely sealed to the underside of the deck, allowing water to slosh into the bilge.
Check for livewell spillage.
Sometimes built-in transom livewells aren’t completely sealed to the underside of the deck, allowing water to slosh over the rim and down into the bilge in rougher water. This is hard to see because it usually requires putting your head or a camera inside the well.
Could water be flowing in through your bilge pump outlet?
Some boats — especially those with lower freeboard — have bilge pump outlet through-hulls close enough to the water that waves can slosh above the fitting. Very low freeboard boats like flats skiffs and bass boats can even have their bilge pump outlets submerged by too many people standing on the aft deck. Most newer bilge pumps claim to have a mechanism to prevent backflow, but it’s worth checking.
Are your through-hull drains well sealed?
Deck drains that run from the cockpit to a through-hull fitting in the side of the boat are common culprits for leakage. These basically consist of a hole in the boat’s liner connects to a hole in the outer hull via a short tube running between liner and hull. When the liner and hull move relative to each other — which can happen in rough water or while trailering — the seals and/or tube eventually fail, allowing water to lead won into the bilge. The same can happen with splashwell drains.
Inspect the underside of your hull-deck joint.
The hull-deck joint, usually concealed behind the rub rail, can allow water in, especially near the stern, where water “slides” up the hull sides at high speed and hits the bottom of the rub rail.
Zombie List
Does your boat ride around slumped over to one side like a zombie? That’s called listing, and it’s not uncommon for boats to tilt to one side or the other. In this case, there’s usually a fairly straightforward explanation:
If you boat lists while sitting still, check your weight distribution.
Boats that list one way or the other while tied to the dock or sitting on the anchor usually do so simply because they’re heavier on one side than the other.
The gear you bring on board every day can affect this, but more often it’s permanent equipment and rigging. Consider the location of your batteries (starting, house and trolling motor), water tanks, trolling motor, shallow water anchor, generator and other large equipment. Chances are you’ll discover the reason for the list.
If your boat lists on plane, experiment with trim and motor elevation.
Single engine outboard and sterndrive boats have a natural tendency to list to port when on plane as a result of prop torque — the tendency of a spinning right-hand propeller to lift the starboard side of the boat. The effects of prop torque get worse the lower the motor is mounted on the transom and the farther it’s trimmed in/down.
If trimming out or raising your motor higher with a jack plate reduces the list, you’ve identified the problem.
If trimming out or raising your motor higher with a jack plate reduces the list, you’ve identified the problem. If motor elevation and trim angle seem to have no effect on listing on plane, you may need to consider other possibilities, like an irregularly shaped hull bottom, a trim tab that doesn’t retract completely, or water in your hull.
Fuel System Poltergeists
Fuel systems are right up there with electrical systems in terms of seemingly supernatural phenomena. A few of the most common apparitions include:
Your 50-gallon tank only holds 40 gallons.
Can’t fit the specified amount of gas into your tank? Occasionally manufacturers misstate tank capacity or pumps aren’t calibrated right, but usually the issue has to do with venting. Because of the angle of your tank, air gets trapped above the rising fuel in an area with no vent.
If your boat is on a trailer, try unhooking it from your tow vehicle and using the jack to raise or lower the bow. At the fuel dock, try moving people and weight to the bow or stern or rocking the boat back and forth to release trapped air.
Your engine runs fine at lower RPM but falters when you throttle up.
When engines start and idle fine but have issues at higher RPM, fuel delivery issues are a common culprit. Check your primer bulb when it happens.
When engines start and idle fine but have issues at higher RPM, fuel delivery issues are a common culprit.
A flat or empty bulb indicates an issue between the bulb and the tank, like a venting problem, a bad anti-siphon valve, or something wrong with the pickup inside the tank. Additionally, fuel lines can deteriorate from the inside out, restricting flow.
You catch a whiff of gasoline at random times when opening a hatch.
Fuel leaks are nothing to mess with but can be hard to positively diagnose. Remember that even if you don’t see gas in the bilge or smell gas all the time, you might still have a leaking fuel tank. If your tank has a small leak near the top, for example, you might only smell gas when the tank is completely full or when running in rough water.
On the other hand, smelling gas at times doesn’t necessarily mean you need to replace your tank. If you keep your boat under a cover, for example, normally vented fumes can collect under the cover even when there’s nothing wrong with your fuel system. And poly (plastic) tanks naturally emit a slight gas odor even when new. Remember too that gas can leak from areas other than the tank, particularly fuel lines, fuel line connections and fuel/water separators.
