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Captain Frank: Sea Chest of Horrors


While the old axiom “Let sleeping dogs lie,” may be sage advice when dealing with Rottweilers, as a marine surveyor I can tell you it’s definitely not the attitude to have with regard to boat maintenance. The various systems aboard your boat won’t continue working flawlessly without proper upkeep, and an “out of sight, out of mind” maintenance philosophy will quickly transform the feng shui of your floating Shangri-La into a black hole of frustration and financial woe.

Most all boats have sleeping dogs and winter is the perfect time to inspect your vessel before they have a chance to wake up and take a bite out of the captain’s quarters. To visually assist in your mission to identify and head off potential problems, hop on board, buckle in, and keep your arms and legs inside the car at all times as we take a ride through the cavalcade of maritime perversions I like to call “Capt. Frank’s Sea Chest of Horrors.” All the more shocking because they’re true!

1. Here, sailor’s ingenuity has once again reared its hoary old head in an effort to sink yet another vessel. The handle of the gate valve controlling the bilge manifold has broken off and been replaced with that venerable standby, locking pliers. Aside from the damage this inflicts to the valve’s stem, chances are the pliers will be “borrowed” by a crewmember for some other important task and never returned — a fact most likely discovered when the valve needs to be closed in a hurry. Gate valves are not recommended for use onboard, particularly in below-the-waterline applications. Their internal mechanisms are prone to corrosion-induced failures and they give no visual indication of whether they’re open or closed as does a true seacock. Worse still, the valve can fail to completely close if they become jammed with trash or debris, allowing water to enter the vessel even after the owner thinks the valve is closed.

2. Cracked plastic thru-hull fittings are a common problem, as a walk through pretty much any boatyard will bear out. Ultraviolet light is the main culprit and while different brands vary widely in their susceptibility to UV damage, some are so poorly made they can fail within the first year. Plastic thru-hulls typically fail where the body of the fitting joins the outer flange, resulting first in a crack and eventually in the outer flange breaking away completely (both shown in the accompanying photo). Once the flange shears off, there’s nothing left to keep the thru-hull in place, meaning it’ll eventually be pulled inboard, leaving a gaping hole in its place. If located near the waterline, such a hole can reduce the vessel’s effective freeboard from feet to inches, meaning a boat needs only to settle slightly before it begins to take on water and sink. Plastic fittings should be inspected at least annually. If you find one fitting that’s bad and the others are of the same vintage, play it safe and replace them all.

3. It took me a few moments to figure out just what it was about this thru-hull installation that gave me the willies. Do you see it — or rather, what don’t you see? At first I thought it was the gate valve (which I’m not overly fond of to begin with, especially in below-the-waterline applications such as this). Then it hit me — there are no hose clamps! The only thing holding the thru-hull, seacock, and hose together are a few pieces of foam PVC pipe insulation and a prayer.

4. Can you spot the problems with this LPG installation? They include an unsecured cylinder, no shut-off valve operable from the vicinity of the LPG appliance, and no pressure gauge. Without a pressure gauge, you cannot conduct leak-down tests, a simple way to check the “health” of your LPG system that should be done on a regular basis (at least monthly). To conduct a leak-down test, make sure the tank valve is open and turn on the solenoid switch to pressurize the line. Note the pressure gauge reading, then close the tank valve — the gauge reading should remain constant for at least three minutes. If the pressure drops, you have a leak (or leaks), which must be found and corrected prior to use. Leaks will typically be found at fittings and connections, although they can occur anywhere in the system due to chafe or physical damage to supply lines or other system components. Use leak detection fluid or a detergent solution to locate leaks. Don’t use solutions containing ammonia (it attacks brass fittings) and unless you want top billing at the Darwin Awards website, never use a lighter to check for leaks.

5. Backup bilge pumps are always a good idea; however, there are a few installation points to consider to ensure they work properly when needed. Backup pumps should be mounted and configured to turn on when the bilge-water level reaches around four to six inches above the turn-on point for the primary pump. This prevents the backup pump from resting in the normal accumulation of bilge water, where it can become clogged with sludge and debris and seize from disuse. Unlike the installation shown, a better option would be to mount the backup pump just below or at the same level as its float switch (shown by the arrow).

6. What, I hear you say, can possibly go wrong with cockpit drains? The water disappears and everybody’s happy, right? Let’s say your boat was manufactured in 1980, a realistic example as there are still plenty of vessels from that era out and about. If the cockpit drain hoses are original (and there’s a good chance they are), it means the safety of you and your vessel hinges on a 33-year-old piece of hose. All hose has a finite lifespan and should be inspected and replaced on a regularly scheduled basis (as per manufacturer recommendations) regardless of appearance. Recommended replacement time frames vary between hose manufacturers, but 10 years is commonly quoted.

7. Swivels are installed between anchor and rode to prevent twisting (particularly with all chain rodes); however, many boaters are unaware they can be installed incorrectly. The jaw fitting of the swivel must be attached to the chain, not the anchor shank, with the swivel eye attached to the anchor shank, utilizing an anchor shackle. When the jaw fitting is attached to the anchor shank, as shown here, it will bind and could fail as the vessel sheers at anchor. The swivel itself should be drop forged (not screwed, riveted, or welded together), and the largest size that fits the chain link without binding should be used.

8. No amount of pumps can overcome a bilge choked with trash and debris. Periodic bilge cleaning is a fact of life with older vessels, but even new boats can be littered with wood shavings, bits of fiberglass, globs of adhesives, and other construction trash that can plug up a pump. Oil in the bilge is just as bad; it combines with dirt to form sludge, a thick gooey material that can clog pumps and prevent automatic float switches from operating properly. And, of course, discharging that oil overboard is bad for the environment and the hefty fines are bad for your wallet.

9. This photo shows the exhaust outlet for a generator that, according to the owner, had failed a number of years before and been removed. Rather than properly capping or removing the now unused thru-hull, the owner chose to simply do nothing, effectively reducing the vessel’s freeboard (and safety margin against sinking) from roughly three feet to three inches

10. Here we have a cracked and severely corroded exhaust riser for a small diesel engine on a 30-foot sailboat. If it’s this bad on the outside, just imagine what the inside looks like — that swollen and corroded fuel shut off control line resting against the riser isn’t looking too good, either. Engine manifolds and exhaust risers should be periodically removed, pressure tested, and fully inspected for corrosion and clogging, as failure here can easily damage the engine or, if water gets into the cylinders, destroy the engine completely. This should be considered standard maintenance, particularly with boats used in saltwater. How often depends on vessel location and use; however, four years is typically quoted (more frequently depending on riser age). 

Frank Lanier

Contributing Editor, BoatUS Magazine