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Boat Maintenance Horrors


Scary things you really never want to come across on your boat.

While the old axiom “let sleeping dogs lie” may be sage advice when dealing with Rottweilers, as a marine surveyor it’s definitely not the attitude to have with boat maintenance. All boats have sleeping dogs that should be coaxed out before they have a chance to wake up and bite the captain. 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 “Captain Frank’s Sea Chest of Horrors.” All the more shocking because they’re true!

Drilling Into Fiberglass No Nos

Drilling holes through cored decking without taking the proper precautions is asking for trouble. Leaky lifeline-stanchion mounting bolts, (most likely due to failed caulking) have allowed water to enter the cored decking beneath. The mounting nuts are drawn so tightly they’re crushing the panel, no doubt an attempt by the owner to not only keep the stanchion from wiggling, but also to try and stop the leak (note the inadequately sized washers and lack of a backing plate).

No backing plate, nuts tightened too far, and incorrectly sized washers are all leading to a leaky lifeline stanchion, right. The photo on the left shows how it should be done.

In a perfect world, your boat’s manufacturer has anticipated where all deck penetrations are necessary and has “de-cored” these areas by reverting to solid fiberglass, allowing you to mount hardware without drilling into the core. But in the case of new installations, your chances are slim to none that any of these areas will coincide with whatever aftermarket doodad you want to mount, meaning you’re going to have to do it the hard way. Anytime you screw or drill through a cored panel, the first rule is properly sealing the core against moisture entry.

Shaft Nut Configuration

Want to start an argument in most any boatyard? Find a boat where the shaft nuts are in this configuration (thick nut first, thin nut last) and tell the owner or yard manager who installed it that they’re backward. It seems like a no-brainer that the larger nut against the prop would do most of the work and that the smaller nut should go on second, to kind of hold it in place. In truth, however, it’s the smaller nut that should always go against the load because it is the “jammed” nut, not the “jam” nut. When the second, outer nut is tightened down, it compresses and deforms the inner nut a tiny bit, rotating it a fraction of a turn. This effectively unloads the threads of the first nut and engages the threads of the second nut. Thus, the top or outer nut actually takes all the load. As the larger nut has more thread area (and more holding power), that’s the one you want as the outer nut. I see prop nuts installed backward all the time while surveying. Will the prop fall off because of it? Not likely. But who wants to find out?

Organize Boat Wiring

Can you feel the frustration of the poor technician tasked with troubleshooting an electrical problem in this mess? Also note the lack of chafe protection where wires penetrate the bulkhead, as well as the evil “electrical tape joints,” which eventually will fall off, leaving exposed, energized conductors.

Cutlass Bearing Replacement

This is one of two cutlass bearings from a twin-engine power vessel that were so severely worn, both shafts were damaged and had to be replaced. A cutlass bearing is a short metal tube (usually of brass) with an inner grooved, rubber lining. The bearing holds the shaft steady as it turns, while the grooves allow water to enter, providing lubrication. Cutlass-bearing replacement is a routine maintenance item; they all eventually wear to the point of looseness, which if left unaddressed can result in a number of problems, from excessive shaft vibration to drive train alignment issues. In cases of severe wear (such as this), the grooved channels are completely worn away, meaning the shaft receives no lubrication from the surrounding water, leading to scoring of the shaft (due to friction) and a reduction in diameter where it passes through the cutlass bearings. The seller had replaced both cutlass bearings the day before the survey, but even with new bearings of the proper size installed, both shafts still had significant play. When removed, it was discovered that the diameter of both shafts had decreased by almost 1/4-inch where they transited the cutlass bearings.

Keep Bilge Pump Float Switches Free

Flapper-type bilge-pump float switches must be securely mounted and installed clear of wires, hoses, and other obstructions that can impede operation of the floating arm or flapper switch. They should also be oriented with the switch aligned fore and aft, and the flapper pointing toward the stern. This is especially important on powerboats; during jackrabbit takeoffs, surging bilge water can damage the flapper mechanism, even ripping it apart in some cases. Installing them close to a bulkhead or frame also helps protect the switch from a torrent of water. Enclosed switches eliminate this worry, but can also be more difficult to inspect and test.

Bottom Paint Haloing

“Haloing” of bottom paint is sometimes observed on boats with bonding systems that are in poor condition or are providing overprotection of the bronze components. It’s most prevalent with vessels using black or other dark-colored bottom paint and is more common with certain brands containing higher amounts of copper. If found on your boat, inspect your bonding system connections (if you have one) to ensure they are clean, tight, and corrosion free. Another good idea is to conduct a corrosion survey to ensure proper galvanic protection is being provided.

Corroded Exhaust Risers

It’s later. Here we have a cracked and severely corroded exhaust riser for a small diesel auxiliary on a 30-foot sailboat. If it’s this bad on the outside, just imagine what the inside looks like (that corroded fuel shut-off valve resting against the riser isn’t looking too good, either, by the way). Engine manifolds and exhaust risers should be periodically removed, pressure tested, and fully inspected for corrosion and clogging, as failure here can easily result in engine damage or even catastrophic failure. 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 recommended (more frequently for older risers).

Boat Caulking Failure

Here’s what it looks like down below if your core gets saturated. Investigation revealed the coach roof and cabin side coring showed high moisture readings. Water likely entered the coring due to caulking failure and leaking at the mounting hardware for a sail track, just one more example of why all deck hardware should be pulled and re-bedded (caulked) every five to seven years.

Frank Lanier

Contributing Editor, BoatUS Magazine