Keeping the Pipes Clear on Seawater-Cooled Systems

Worth Its Salt

Sea water cools many onboard systems, but critters and gunk can eventually clog the plumbing.
Here’s how to keep your pipes clear.

Your boat depends on sea water, and I don’t mean just for staying afloat. Besides engine and generator cooling, most cruising boats have at least one appliance, usually an air-conditioning unit, and sometimes more than one, that depends on sea water for cooling. Sportfishing boats add ice makers, too. Larger yachts have hydraulics to operate stabilizers, and oil needs cooling when the yacht is underway. In short, seawater plumbing is an important component on many boats, but one that’s often overlooked.

That is, until the air-conditioning system craps out on a hot summer day because its cooling-water flow is blocked by seagoing gunk—which always happens, of course, when the boat’s full to the gunwales with guests. Then even the most unenlightened skipper realizes the need to keep the water flowing. Who needs the in-laws dripping sweat all over the varnish? How often this sort of thing happens depends on where you boat: Up north, where the water’s cool and the boat’s hauled in the winter, you can usually get away with cleaning—pros call it “descaling”—once a season, but move south and the critters proliferate in the plumbing to such an extent that you may find yourself in need of descaling every few months. You can do this yourself with a store-bought system or buy the components and build one yourself. Or you can go high-tech and stop the plumbing problems and descaling madness once and for all.

Salt water looks clean, but it’s really quite dirty. It carries embryonic barnacles and other small marine critters, algae, salt and other minerals, and, especially in harbor, silt and pollution. (That’s why holding tanks and other components on salt-water-flush heads get smellier than fresh-water-flush MSDs: It’s not the waste, but the algae and bacteria that enter the system with the flush water which cause the problem.) A seawater strainer stops the big stuff from getting into the lines, but the small bits pass right through. Cleaning the strainer regularly is a good first step in keeping the water flowing, but most of us don’t do it often enough. And the real nasties get past the strainer anyway.

So, what happens? Because the constant flow of seawater makes for a fecund environment for organic propagation, barnacles and other marine growth thrive and eventually clog plumbing related to air-conditioning condensers, heat exchangers, oil coolers and whatever else they can find to inhabit. Add salt deposits left by hot sea water, combined with the small diameter of many marine hoses and pipes—most appliances circulate just enough water to keep things cool under normal conditions—and it doesn’t take long to reduce water flow enough to stop a given system from working. Sure, checking the outflow of cooling water is a smart practice, but, again, not foolproof: A constriction can happen so slowly that you may not notice the gradual diminishing of the flow. And under such circumstances, damages can ensue.

One place that’s nirvana for barnacles and algae is Jupiter, Florida, where Dr. Louis C. Cosentino keeps his 72-foot Viking Judith Ann, a boat with lots of seawater-cooled systems. Some years ago, his captain was spending lots of time and money descaling all of them every few months, while fellow captains of Vikings who move to South America in the winter for billfishing found they were descaling monthly. The major problem was barnacles colonizing intake hoses. But eventually, Dr. Cosentino decided there must be a better way. And after two years of research, prototyping and testing, he and his son Daniel developed a simple and comparatively affordable electrochemical disinfection technology they’re calling the ClearLine System. It can be installed aboard almost any boat in a day or two and, once installed, reduces periodic chemical descaling to a not-so-fond memory. (Note: The plumbing has to be clear to begin, so one last descaling may be necessary when installing the ClearLine.)

You should know: The Cosentinos aren’t a couple of guys tinkering in the backyard on weekends. Dr. Cosentino has a PhD in biomedical and electrical engineering, Daniel an MBA in marketing. Together, they hold more than 100 U.S. patents and more than 300 international patents, mostly in the medical field, and have founded and sold two successful companies to produce some of these inventions. Among other devices, the Cosentinos have developed sterilization and disinfection systems for kidney dialysis and oxygenators for open-heart surgery. But even with all their experience, it still took the Cosentinos two years to perfect the ClearLine system, in the process ensuring not only that it works, but that it won’t damage a vessel’s plumbing. Indeed, after thoroughly water-testing the ClearLine, they sea trialed it for a year aboard Judith Ann. Then once they had a final product, the Cosentinos founded a third company, ElectroSea, to market the new device.

What is ClearLine and how does it keep the barnacles away? The technology is based on electrochemical water disinfection, a process used in many industries to produce bacteria-free water without using chemicals. Water—in this case, sea water—passes through a chamber containing electrodes either made of or coated with particular metals. Choosing the right metals for both anode and cathode is critical to developing a functional system and depends on several factors, including the properties of the water being disinfected.

The Cosentinos call their electrode chamber a ClearCell; it should be installed as close to a boat’s sea strainer or seawater pump as possible. A low-level current (ClearLine works on 12- or 24-volt input) changes some of the salt water passing through the ClearCell into chlorine and hydrogen. The chlorine kills bacteria, the barnacles, the algae and any other organic pollutants in the water. And yes, hydrogen is explosive, but Dan Cosentino says such a small amount is produced, and for such a short time, that it’s inconsequential. (Hydrogen is a byproduct of most electrochemical disinfection processes, by the way.) As the chlorinated water passes through a boat’s plumbing, the molecules reform themselves, so by the time it’s discharged, the water contains about as much chlorine as you’ll find in typical municipal tap water. To make the system even more effective, some of the chlorinated water from the ClearCell is shunted back to the relevant sea strainer to start disinfecting as close to the inlet seacock as possible.

The ClearCell however is only half of the story: There’s also a sophisticated electronic controller that regulates the level of chlorine produced in the ClearCell. “The ClearCell has to generate a precise level of chlorine because too much chlorine can damage other systems in the vessel,” said Dan Cosentino. The amount of chlorine is flow-dependent, he explained; the -controller senses the demand for cooling water and adjusts chlorine production accordingly. This is especially important in cooling systems like Viking’s Central Seawater Distribution System, where central seawater inlets serve many onboard appliances.

The controller has other functions, too. It’s used to initiate a cleaning cycle, to rinse the electrodes—Cosentino said this is necessary more often in areas with lots of silt in the water. In plumbing systems like Viking’s, with two primary seawater intakes and two water pumps, the controller can switch between pumps at programmed time intervals. This evens out the wear on the pumps and gives both of them regular exercise so they work properly when called upon. The controller initiates an Inhibit function when an appliance comes online that cannot use chlorinated water, such as a baitwell on a sportfisherman. The controller senses when the baitwell circuit is energized and inhibits chlorine production in the ClearCell until the circuit is de-powered.

The controller is built of heat-resistant components and is designed to be mounted in the engine room. Once installed, it requires minimal attention. The ClearCell needs no scheduled maintenance, but will need a new electrode periodically. “The electrode has an estimated life of approximately five years,” said Dan Cosentino, “but the actual useful life is flow-dependent.” If the sea water is muddy, the electrode will need occasional rinsing, he added.

ElectroSea builds three ClearLine models for seawater flows of up to 50 gallons per minute, plus a fourth model for Vikings and other yachts with dual primary seawater inlets and pumps. The ClearCell can be plumbed into systems with seawater pipes from 3/8 to 1.5 inches in diameter. Dan Cosentino said vessels with pipes greater than 1.5 inches and flows greater than 50 gallons per minute can install two ClearLine Systems in parallel—a T-fitting on the input, then two ClearCells, then a T-fitting on the output.

ClearLine systems range from $4,000 for the smallest unit to $8,540 for the largest (that’s the one with provisions for dual inlets and pumps) plus installation, which usually takes only a day or two. “It’s mostly a plumbing exercise,” said Dan Cosentino. The ClearLine must be installed by an ElectroSea authorized dealer, but there are plenty of them, especially in South Florida, with more coming on board all the time.

According to Tom Carroll, president and CEO of Princess Yachts America, the ClearLine system effectively costs nothing. Carroll installs ClearLine on all the inventory boats he orders, and recommends it as an option to all Princess customers. “At $1,200 to $2,000 to acid-clean a system,” he explained, “the ClearLine pays for itself the first year in Florida, where growth often returns within 60 days after cleaning. You get barnacles, algae, you name it. If a given system isn’t acid-cleaned regularly, hoses can clog and burst, or air-conditioning condensers clog, which costs even more.” And with every cleaning, he added, there’s the chance of an acid spill. “The ClearLine ensures that growth never gets in there; it gets rid of a headache for our customers that they don’t really need.”

This article originally appeared in the February 2020 issue of Power & Motoryacht magazine.