Leaving sight of land raises the self-reliance stakes substantially. Getting your boat ready is an exercise in finding the potential weak spots, and then building a plan to cope with any failures.

Prepping a boat for bluewater travel is an order of magnitude more challenging than typical weekend boating or even coastal cruising. It is an inconvenience if you have an engine failure a few miles from a marina and have to call for a tow. It is a dramatically different scenario if you’re three days out of the Chesapeake Bay on the way to Bermuda.

The conversation about prepping a boat for bluewater travel traditionally focuses on repairs at sea, and on having the tools and spare parts to accomplish those repairs. But these days, many boat systems are so complicated (think black boxes filled with circuit boards and other components) that it’s unrealistic to believe most boaters can fix them underway.

In those cases, it is more important to be able to analyze a system and figure out a workaround. For some critical systems, the answer will be to carry complete spare parts; for others, it may be wise to have a secondary system ready to go.

Here’s a mechanic’s-eye view of typical systems aboard, and what to do if one of those systems fails.

Making It Go

We’re driving powerboats, so nothing is more important than the propulsion system performing well. Modern engines are incredibly reliable, provided their maintenance has been meticulously performed and they are supplied with clean fuel and a steady supply of seawater.

What are some of the weak links? Single-engine boats have to protect their shaft and propeller. Some boats add wing engines as get-home propulsion. You might carry a spare prop, but it would be the rare boat owner who could replace a prop alone in the ocean (although it is certainly possible with the correct tools and knowledge). Line cutters are popular because, in some cases, they help with snagged lines. Aside from that, any repair would include scuba gear, or many trips with a snorkel and sharp knife.

Twin-engine boats have built-in redundancy. Barring a situation where both props are wrapped in a fishing net, a problem with one set of running gear will still allow the other side to get the boat home. Running on one engine can leave the dead engine with no lubrication for the transmission or shaft seal, thus damaging the transmission or overheating and possibly breaking the shaft seal. The unused shaft should be tied off and immobilized against turning.

Your fuel system must prove clean. Motion in the ocean will stir up any sediment or water in the bottom of the fuel tank, and those substances can quickly overcome the fuel filter system. This is one of the primary reasons to install dual primary fuel filters: If one becomes clogged, you can quickly switch to another clean filter. Depending on the rate of clogging, you may be able to change the clogged filter back at a dock. If it’s clogging quickly, then you can change out the clogged filter underway without stopping the engine.

For far-ranging boats, fuel polishing systems that circulate the fuel through filters at a relatively high volume can remove any errant debris or water before it can cause a problem. A light sprinkling of debris in the sight glass is normal and shows that the filter is doing its job, but an inch of crud or water in the bottom indicates a bigger problem in the fuel tank. Vacuum gauges installed on your fuel filters will tell you the condition of the filter.

If there is any suspicion of dirty fuel, boats without installed fuel polishers can call shore-based companies to clean their fuel and tanks before leaving the dock. Visually check the fuel filter bowls for sediment or water after at least a few days of running.

Fuel management is also critical. It is important to know how much fuel your boat uses at different rpm. Most newer multifunction displays can show gallons per hour of fuel burn when a fuel sensor is added in the fuel line (new, computer-controlled engines have this feature built-in). Still, it is wise to verify accuracy by running at a consistent rpm and tracking fuel usage at fill-ups.

All displacement craft have an optimal speed at a certain rpm that is evident right before the boat tries to push up out of its displacement hole (about 1.3 times the square root of the waterline length). Any further rpm just uses more fuel and typically only moves the boat a few tenths of a knot faster. Tracking fuel burn rates allows you to calculate your range, plus a reserve.

Semi-displacement or planing boats may be able to run faster than displacement speeds, and average better nautical miles per gallon. Taking the time to establish a table of fuel burns and speeds at different rpm will provide confidence in your fuel usage planning.

Before heading offshore, it is also wise to make sure the bottom and running gear are clean. Any extra growth will only slow the boat and make the engine work harder, thus using more fuel. Perform a wide-open throttle test for at least 15 minutes. A properly functioning engine will not overheat in that time frame, and a successful test will prove that if you need full power at some point, you will have it.

Inspect the engine while it is running wide open. (Make sure to do so with someone else at the helm, long hair in a cap, ear protection in place, and loose clothing tucked in.) Look for any leaks, water, fuel or exhaust. Check that the belts are running smoothly. Use a non-contact thermometer to seek out hot spots in the cooling system, alternator and exhaust. Check the main shaft seal as well. Conventional boxes with stuffing should not exceed 140 degrees Fahrenheit (lower is better). Hotter than that, and the wax in the stuffing can melt out. Dripless boxes should be the temperature of the injection water, which normally will only be 10 degrees to 15 degrees above seawater temperature.

When you’re offshore, the ocean will find ways to enter a poorly installed tank vent—ways that you wouldn’t encounter during less-strenuous cruising. Inspect your fuel vent hose and vent location on the hull. Can a slapping wave make its way into the tank? Vents should be angled aft and mounted as high on the hull or superstructure as possible. Inside the hull, the hose should loop up from the vent first, then down to the tank.

Alternators And Belts

If your alternator seizes, you might think that you can simply run your generator to charge your batteries via the AC battery charger. However, what if the belt cannot be removed on the seized alternator because that belt also drives the engine’s fresh and/or saltwater pumps?

Take a look at your engine. If it has a serpentine belt (a single flat, ribbed belt wound around all the pulleys), then a seized alternator will take the engine down. It would be wise to carry a spare that’s already fitted to the correct pulley for your engine. Know how to remove the bad alternator and install the replacement on the engine. If the alternator does not have the pulley installed, replacement of the pulley may require an impact driver and the correct socket.

Many V-belted engines have the same problem, but, if you don’t have a spare alternator (depending on the configuration), it may be possible to MacGyver a DC water pump—perhaps a washdown pump—to supply salt water to the engine. The DC pump may not push as much water, but if you keep an eye on the temperature gauge and keep the rpm under control, this may get you to your next port. It will be important to turn off the pump with the engine, so it doesn’t fill the muffler and backfill into the engine.

Get The Water Out

The stakes for a leak rise dramatically if there is 1,000 feet of water beneath your keel.

Conventional wisdom calls for at least 100 gallons of pumping capacity per hour for every foot of boat length. This means a 40-foot boat should have at least 4,000 gph worth of pumps.

Clean bilges that are free of debris should be a no-brainer. You don’t want anything to reduce pump capacity. Segregated bilges with independent bilge pumps can save the boat if one pump fails. Large-capacity crash pumps mounted higher in the main bilge can offer an additional layer of security.

It’s also smart to have tapered plugs on board for sealing broken hoses or plumbing, and repair materials to help plug smaller hull penetrations. Larger hull failures have even been dealt with by screwing locker tops to the hull with copious amounts of 3M 5200. That might not be a pretty repair, but keeping seawater on the outside is the prime directive.

Finding Your Way

Barring a catastrophe that takes out all of our satellites, rendering the GPS system useless, it is easy these days to install redundant GPS-enabled equipment. Even if a problem occurs with your NMEA 2000 backbone that carries information between units, you can still use the devices as standalone units. Tablets and phones also have integrated GPS; as long as you have a navigation app loaded, you have additional backups available in these devices.

Nevertheless, it is wise to understand the locations for the fuses for all your installed equipment, and to have backups on board. The additional motion can also wreak havoc on poorly secured wiring, causing connections to loosen or wires to break. If you look behind your electronics and there is a mass of unsecured, unlabeled wiring, you are asking for trouble. Set aside a morning of zen with your electronics. Trace, label and secure everything.

Steering

There are several ways to connect the steering wheel with the rudders. Some boats have cables, chains and quadrants, but the most common way is with hydraulic lines and a ram. Check the plumbing run for leaks, have spare fluid aboard, and know how to top it off.

Some systems have separate autopilot rams that offer an additional level of redundancy; if the main system fails, the autopilot can be used to steer you home.

The boat should be equipped with an emergency tiller that can be fitted to at least one rudder, in case all systems fail. This will require bypass valves on the hydraulic system or physical removal of the rams to reduce the effort. Checking how well your emergency tiller works in protected waters will give you confidence that all the bugs are worked out. Quite a few factory installations have unworkably short tillers or impossible sightlines. We’ve seen emergency tillers that must be used in the aft cabin, for instance.

As a side note, if steering is lost in twin-engine boats and the rudders can be secured so they don’t flop around, often, the boat can be steered by varying throttle inputs to each engine and then taking the engines in and out of gear when the boat is docking.

Water, Water Everywhere

Humans can survive for weeks without food, but only a few days without water. Ample tanks are one solution. Watermakers are another.

Prudence dictates that there should be enough water aboard for each crew member for the entirety of the trip, not counting what a watermaker could produce. Certainly, spare pre-filters, cleaning solutions and oil for watermakers should be carried. Beyond that, add some spare hose and hose clamps, and perhaps some extra plumbing fixtures. These are just about the only user-repairable items on a watermaker, especially for a self-contained, computer-controlled unit.

Boats were traditionally fitted with a few hand or foot pumps for fresh water (and sometimes salt water), and the pressure water pump was turned off on the passage. This would prevent a leak or a dribbling faucet from running all your precious water into the bilge. Even now, it is not a bad idea to leave the pump switch off unless water is going to be used while underway, and to keep an eye on the tank levels as part of the watch change.

Without manual pumps, an extra electric water pump could be a lifesaving spare in the event of a pump failure.

Heads

Manual heads all have rebuild kits available. It is wise to carry them. If there are multiple electric heads aboard the boat that are operated by a single vacuum generator or central processing control unit, and that pump or CPU fails, none of those heads may work. All vacuum generators have rebuild kits for the seals and valves, and those are valuable spares to have, but if the motor fails, the only solution will be a new pump, which may also be wise to carry aboard.

The same can be said about the CPU, unless there is a way to override the control with a simple on/off switch. Understanding the system will keep you from having to resort to the old standby no one wants to use for long: the bucket.

Communication

Unless you have satellite communication capabilities offshore, you will lose line-of-sight connection to all cell towers relatively quickly. Prices are falling for receivers, but shore-level speed and volume are still expensive out on the ocean.

Satphones are available for voice communication and limited internet- or text-only devices, along with position-only devices to help people at home track where you are. Single-sideband radios are still available and have limited modem capabilities, although satellite equipment has simpler operating systems.

Budget is often the biggest factor for choosing a system and an amount of redundancy. And, short of proving that these devices are receiving proper power (you do have a multimeter aboard, don’t you?), there is typically not much that can be fixed without a deep knowledge of electronics and the correct spare parts.

Self-Reliance

One of the things most valued about boating is the personal satisfaction of being able to cope with whatever challenges the sea presents. Overcoming difficult situations and safely returning to shore provides an enormous sense of accomplishment.

The best voyages are ones with no drama at all, but if something does go wrong, and the problem is mitigated one way or the other, these are the voyages we remember forever.

This article was originally published in the October 2022 issue.