any boat owner can attest, it isn’t just crotchety old Aunt Emma that suffers
from annoying leaks. From the water
they float in to the myriad of liquid carrying systems onboard (fuel, coolant,
oil, hydraulic) the potential for leaks abound, causing anything from spoiled
food and equipment damage to sinking and even explosions.
The sudden appearance of water in the bilge or a mysterious fluid in the engine room should be cause for alarm – after all, if you don’t know what’s leaking it could be anything, possibly a sign that some vital component is on the verge of failure. Leaks are your boats way of telling you that something is wrong and as they don’t fix themselves, it’s imperative to find and correct them as soon as possible.
tracking down leaks, patience and careful observation are virtues, although a
good sense of smell doesn’t hurt in some cases (such as with fuel or
sanitation system leaks). Color and consistency of the leaked fluid itself can
also point to likely sources, coolant and transmission fluid leaks being a good
when leak hunting you’ll need good lighting, such as a small, bright
flashlight or drop light. Depending on the type of leak, other possible items include
paper towels, a wet /dry vacuum, a small inspection mirror, children’s felt
markers or sidewalk chalk, a can of Soft & Dry underarm deodorant, a live
chicken and a weed-eater (OK, I made the last two up, but we will discuss the
Soft & Dry trick in a moment).
in the bilge is never a good thing, particularly in large, increasing
quantities. The first thing to
determine in the case of clear water leaks is whether the water is salt or
fresh. If fresh (unless the boat
itself is in fresh water) the potable water system is the likely source
(discounting rainwater, which could also be a possibility if the water appears
after periods of rain).
it’s saltwater, unless you’ve ran aground or otherwise damaged the hull,
likely suspects include through-hulls, seacocks (including the hoses), through
hull mounted transducers, strut fasteners, or any other hull penetrations below
the waterline. Sailboats can also
have issues with leaking keel bolts, while powerboats can leak around trim tabs,
swim platform mounts, or U-joints and bellows (for those with stern drives).
the leak only occurs while underway, the engine raw water cooling system may be
suspect, as well as stuffing boxes for the shaft or rudders.
Stuffing boxes for the shafts should typically leak three to four drops
per minute while underway, however they shouldn’t leak at the dock.
Rudder posts may not leak a drop while in the static position, but gush
water while underway – look for tell tale sighs of corrosion or verdigris (in
the case of bronze hardware), which typically signifies a leak.
sailboats, leaks underway when heeled could indicate anything from loose keel
bolts to back-siphoning through a leeward bilge pump discharge through-hull with
an inadequate (or no) riser loop installed.
down bilge leaks
lucky enough (from a leak-tracking standpoint anyway) to spot a steady stream of
water, you’ll likely have to do a little investigative work to find the source
of the leak. Leaks can be easier to spot than track to their source,
particularly as the water may drip or become noticeable a boat length away from
where the actual leak is.
first step in locating a non-obvious bilge leak is to pump or vacuum the section
of bilge where the leak seems to be coming in, dry it as much as possible, then
place a folded paper towels fore and aft of the area.
Wait a bit, then check the towels at each end of the bilge area you’re
testing to see if any are damp. If
one of the end towels is wet, then the adjacent bilge areas is suspect, meaning
you simply move to that area and repeat the process.
Work through as many compartments as the boat has and you should locate
the one where the water is actually entering.
you’ve narrowed it down to one section of bilge, there are a couple of ways to
determine where the water is coming from. One
option is drying the bilge and covering it with paper towels, then simply
watching to see which ones get wet. Another
is drawing a few lines along both sides of the bilge with a children's water
washable felt pen or sidewalk caulk – check back after a bit, look for runs,
then work your way up the hull till you find the leak.
if all else fails you may want to haul the boat and check the exterior for
damage, at which point you can also run some fresh water into the bilge and look
for wet areas (once the hull is dry).
/ generator exhaust system leaks
system leaks are a serious issue, not only because of the potentially
catastrophic engine failure they can herald, but also due to the possible
introduction of CO into the interior of the vessel, a situation with potentially
leaks (between manifold and block for example) can often be found by feeling for
escaping exhaust or holding tissue paper near the suspected area and watching
leaks in manifolds, exhaust risers, or mufflers are normally accompanied by
corrosion, stains, or “running rust” originating at the leak itself.
Lacking the above signs, another option is to clean the area completely
(non-flammable aerosol disc brake cleaner works well), then spray on the
deodorant mentioned above and let dry (this could take five or six hours on a
cold engine). Once dry, the
deodorant leaves a uniform coating of white powder that not only makes a leak
easy to spot, but is also easily removed.
up we’ll tackle fuel system leaks, one of those leaks that common sense says
must be found and fixed sooner rather than later.
For suspected fuel leaks at the engine (and this works for oil,
antifreeze, or any other engine leak) clean and dry the area beneath the engine,
then cover with paper towels or oil pads and check for wet areas (bearing in
mind the engine may have to be running to generate the leak).
you suspect fuel fitting leaks, clean the connections with alcohol and tie a
little wad of toilet paper or paper towel on each fitting.
Go grab a cup of coffee, then come back and look for evidence of leaking.
down leaks is likely the closest thing to detective work most of us will get and
while it may not have the excitement of solving a cold case, finding a
persistent leak does have its own rewards.
Just don’t let the other boaters at the dock know how good you’ve
gotten in sniffing out leaks – they likely have a few of their own.