Hose Maintenance


Tue07292014

Last update04:04:10 PM

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Hose250Does your boat have hardening of the arteries? Pardon the joke, but few people think in terms of vital arteries on board their boat. Of course, there are several. In some cases, a clogged artery can cause a fire. In others, a burst (or disconnected) artery can sink your ship in minutes.And, yes – old rubber arteries can harden with time, exposure to heat, petroleum and water. Then, they can crack or fail.

Recently, a new problem called ethanol caused the interior wall of my Whaler’s fuel hose to collapse, inexplicably cutting off the fuel flow and disabling the boat. My older fuel system was not built with ethanol in mind.

I was rescued. My engine torn down and I finally paid for three carb re-builds, a new fuel pump and laterally, a new battery before we guessed that a perfectly secure-looking hose was the problem. The “fix” was $35 after hitting nearly a grand in wrong-guess repairs. I got stranded three times, too. I can’t put a price on that but the embarrassment factor is pretty high.

The arteries that are on your boat (even a small boat) may include various forms of “marine hoses” including all flexible hoses, tubing, ducting, conduit, exhaust, connecters, fuel lines and even tiny engine hoses that are installed on your boat.

Marine hose connects, services and protects virtually all the critical equipment and systems on the boat. It conveys fluids, vapors and gases and in other cases, protects wiring, cables and other connections.

The failure of marine hose on a boat can have catastrophic effects like explosion, fire, flooding, sinking and more.

There is hose from the fuel filler to the fuel tank. The tank has a vent line that is usually a copper tube, a fuel hose from the tank to the fuel pump and then another hose to the fuel filter. From there, yet another hose takes the fuel to the carb or fuel injection system and on diesel engines, there is even a return line to take unneeded fuel back to the tank!

The engine needs cooling water and that usually comes from a through-hull fitting to a hose that runs to the engine block or heat exchanger. Sometimes, more cooling lines are external to exhaust manifolds and, of course, almost all pleasure craft inboard engines send their exhaust and cooling water through high temperature hoses and out an exhaust pipe in the transom or through the drive unit and out through the propeller hub.

Let’s not get started on all the hoses and fittings that your boat has if it is equipped with running water in the galley, the head, a cockpit refreshment centre or ice maker on the bridge.

All of these hoses are the vital arteries needed to circulate the fluids and gasses that make your boat work. And, they are relatively cheap. We were told that all the hoses in a typical 40-foot cruiser are probably less that $300 to replace.

Compared to the costs of the systems they serve and protect, at least once a year, shouldn’t you patrol the boat’s interior spaces and engine room to police the condition of those hoses?

What about the clamps that hold them on? Metal can fatigue and snap. Some hoses only have a 2- or 3-year life expectancy. What we are suggesting here is that this fall, after a long season of use, vibration, heat and fatigue, replace all your hoses and use snug new clamps – double clamps on all through hulls.

To quote Bill Shields, president at Trident Marine Systems, who sell all manner of high-end hoses, “During my years in the US Coast Guard as a search and rescue pilot, I witnessed many disabled boat incidents that turned into tragedies; and there is no way of knowing if a hose failure was the root cause. But, as an example, the internal delamination of a marine fuel or water hose can be the root cause of an engine failure that leaves the boat disabled and drifting or worse.”

Tom Wise, Vice President for Corporate Development at North America’s largest marine hose manufacturer Novaflex, echoed the concern. “Inspect your hoses at least once a year,” he told us. “You can quote me on this – ‘All hose will fail in time’ is a comment I have made over and over. We are alarmed at how many boat owners take their hoses for granted, replacing them only when a leak or problem occurs. But by then, the contents of your fuel tank or holding tank could be sloshing around your bilge.”

The engineering authority, SAE, sets out specifications for marine hose but we are told these specifications are generally not as stringent as those for automotive use. However, NMMA and ABYC standards are based on the SAE requirements.

A new SAE spec hose is perfectly OK when applied to the job it was designed for but among boat and engine companies alike, there is little incentive to use hose that exceeds the minimum SAE specs. From there, it’s all about price.

The hose just needs to meet the minimum SAE specifications and survive the warranty period, and often that is only 1 year. Some hose has a 2-year, 3-year or 5-year warranty. When you get into high-end hoses like silicone exhaust hoses, there can be a 10-year warranty but that does not mean you can ignore the hose for 10 years.

Tom Wise talked at length about ozone. “O3” is given off by most electrical current flow products; your air conditioners, fans and so on.

Tom reminded us that the engine room ventilation system in most boats (notably large cruisers) is designed to function when the boat is moving. When it is closed up tight at dockside, but you are running the A/C and other current flow accessories, ozone can build to very high levels. The extra oxygen molecule in ozone makes it highly reactive and that greatly accelerates the hardening and deterioration of materials like your rubber hoses. Hoses can suffer serious deterioration in just a few months.

Rubber is cured from its natural gummy state with a combination of sulphur, peroxide, heat and pressure. Reliability and life expectancy depend on the “heat history” the hose has been exposed to. More heat increases the “cure” and causes the hose to become hard and brittle.

The hose may look fine until a big impact or other occurrence causes it to bend or flex. New hose is resilient. Old hose cracks or breaks.

Imagine if that resulted in even a pinhole in a propane hose located in an enclosed space where a nearby appliance or switch could generate a spark.

Also, lack of heat…or actually extreme cold during winter storage can cause rubber to go crystalline at -30 degrees and less. That can result in fractures at clamps and bends.

So, “When in doubt, remove it from service” is a great bit of advice from Tom Wise. Hoses are not expensive. Replacing them with new hose and clamps is easily within the scope of normal Do It Yourself projects. Your dealer can also do it and if you realize how little the cost difference can be, you might ask for high-end replacement hoses.

“I can tell you that our top quality hose is virtually all bought by consumers after they have experienced a failure,” Tom Wise told us, “then they are happy to pay!”

That makes good sense and then, if you have an older boat that is now exposed to ethanol or biodiesel products that it was not designed for, hose replacement and upgrades are essential. Do it now or, do it in the spring but before your boat hits the water in the summer of 2009, carefully inspect all hoses and fastenings and replace any that are more than a few years old.

Keep everything circulating and in good health!

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