PracticalBoater
Seaworthy | From The BoatUS Insurance Files


Don't Get Hosed By
Busted Hoses

By Beth Leonard
Published: February/March 2014

Not replacing a worn-out hose, or using the wrong hose when you do, can lead to problems ranging from a smelly head to a sunken boat.

Photo of a sinking powerboat

When a 32-foot sailboat sank at a New York dock, the investigating surveyor noted that the hose connected to the engine-cooling water intake was cheap radiator hose from an auto-parts store. The flimsy hose had softened and split where it connected to the through-hull. Further inspection revealed that radiator hose was used nearly everywhere — cockpit drain lines, freshwater lines, bilge pump, and even the diesel fuel fill.

Tip iconHoses are sized by their inside diameter (ID) and hose fittings are labeled based upon the ID of the hose
they fit.

There's no such thing as an all-purpose hose on a boat. No single hose type can withstand engine exhaust, bring fresh water to the galley, safely transport gasoline to the carburetor, drain the cockpit, and flush the head. There's also no such thing as a hose that never has to be replaced. Most manufacturers rate hoses to last between 10 and 20 years. If your boat is 10 years old or more, it's time to inspect all the hoses aboard to see which have passed their useful life. Any hose should be replaced if it shows any signs of bulging, softness, or cracking. Let's take a look at the most important attributes for each hose type, other ways to tell when a hose has passed its useful life, and which hose is best for each job on your boat.

Fuel Hose: Chemical Resistance And Low Permeability

Photo of a failing fuel hose

A failing fuel hose, like this one, poses a serious fire hazard and must be replaced.

Gasoline-powered boats have very specific requirements for hose that are so demanding, they're federal law. Hoses that carry gasoline must be USCG approved and marked with their manufacturing date and J1527 A1, A2, B1, and B2. Gasoline hoses are usually made of rubber compounds. A-type hose is thicker than B-type and has to pass a 2.5-minute burn test, while type 1 hose is far less permeable than type 2. The EPA's requirements for permeability are even stricter than the Coast Guard's and are designed to limit gasoline evaporation through the hose. The designation "-15" after the hose type shows that it meets the EPA standard and will not allow more than 15 grams of gasoline per square meter to evaporate through the hose in 24 hours. In the end, it makes sense to just use the best — A1-15 — for all gasoline hoses (while not required, this is also the best choice for diesel hoses as well). Manufacturers say that fuel hose has a useful life of about 10 to 20 years. Running a rag over each hose can help you tell if it needs to be replaced; take a sniff and if you smell gasoline, the hose has become permeable and it's time to install a new one.

Exhaust Hose: Temperature Resistance

Photo of an exhaust hoseExhaust hose should be double hose clamped to prevent deadly
exhaust gases from escaping into the boat.

Temperature resistance. Exhaust hose is one of the most critical hoses onboard. A faulty hose will not only allow the engine to pump the boat full of cooling water, but it will also leak deadly carbon monoxide. If your engine's cooling water system fails, the exhaust hose is often the first thing to suffer as it takes the full brunt of hot exhaust gases. The higher its temperature rating, the longer it will hold up in an overheating situation. Two-ply exhaust hose with heavy-walled, helix-reinforced rubber marked "SAE J 2006" is designed to withstand temperatures of around 250 degrees F. Some silicon rubber exhaust hose can take up to 500 degrees F, which is necessary for high-performance engines, and come with a 10-year warranty along with a premium price. Serious overheating can destroy the interior of the hose; replace it even if you cannot see any damage to the exterior. Consider replacing rubber exhaust hose at around 10 years; silicone hose should be good for 20 years.

Through-Hull Hose: Strength

Photo of a corrided thru-hull hose
Even the proper hose lasts only so long — this hose is past due for replacement.

Tip iconStiff hoses can be easier to install if the end is dipped in very hot water for a minute; this allows the end to stretch more easily.

Through-hull hoses are really just an extension of a hole in your boat, the above- or below-waterline fitting to which they are attached. As such, any through-hull hose must be exceptionally strong and long-lasting, and designated as suitable for use below the waterline; look for a label on the hose itself or wording in the manufacturer's description. Water-intake hoses also need to be rigid enough to withstand suction from the pumps. Hoses that attach to through-hulls are typically made from rubber and reinforced with metal or plastic spirals. They should not be bent at too tight an angle or the hose will be weakened. Two-ply pickup hose intended for use in wet exhaust systems can be considered the gold standard for raw-water intake hose. Where heat is not an issue and some flexibility is required, extra-heavy-duty smooth vinyl hose with a hard PVC helix can be used. The lifespan of these hoses varies with their job, but after 10 years, consider them all suspect.

Bilge Pump & Live-Well Hose: Minimal Flow Restriction,
Maximum Flexibility

Photo of a cracked bilge hose

Avoid corrugated bilge pump hose like this one which tends to fail at the corrugations.

Bilge-pump hose needs to be strong enough to resist attack from chemicals that find their way into the bilge. Hose for both bilge pumps and live wells also needs to be extremely flexible to go around tight corners, reinforced to prevent crimping or collapsing, and have smooth interior walls to allow water to flow freely. When you look in your bilge, you may well find corrugated (inside and out) polyethylene hose with molded cuffs, which provides excellent flexibility and chemical resistance at an affordable price. However, it's vulnerable to abrasion, and the internal corrugations reduce water discharge flow by as much as 30 percent. Heavy-duty multipurpose vinyl hose makes a better choice for bilge pump or live-well applications. Replace any hoses if they're more than 10 years old.

Sanitation System Hose: Low Permeability

Photo of a sanitation hose
High quality sanitation hoses will pass the sniff test for years to come.

Tip iconUse the best marine-
grade 316 stainless hose clamps. Clamps that are embossed rather than perforated are much stronger and last longer.

A leaking seawater or fuel hose poses more danger, but a burst holding tank hose is many boaters' worst nightmare. Aside from being strong, thick-walled, and smooth inside, sanitation hose also has to have the least permeability possible — use the wrong hose, and any sensitive noses aboard will object in very short order. Running a clean, damp cloth over it and taking a sniff is the best way to test whether the hose has become permeable and needs to be replaced. You'll want hose labeled specifically for sanitation use with a smooth bore and heavy wall. Reinforced PVC hoses don't measure up to the sniff test in the long run, and multipurpose vinyl hoses are vulnerable to antifreeze. The newest in sanitation hoses are made from sophisticated plastics that contain odors and can handle winterizing chemicals; some even come with a lifetime odor-free warranty. To prevent premature aging and the accompanying unpleasant odors, run hoses so that there are no sags or loops to collect standing water.

Potable Water Hose: Chemically Inert

Photo of a potable water hose

Look for NSF 61 on hose used to carry drinking water.

Hoses that carry drinking water have to be made of FDA-approved, nontoxic materials so that chemicals from the hose don't leach into the water. Older hose will be marked "FDA approved"; on newer hose, look for the designation NSF 61, which means that it meets the National Sanitation Foundation's guideline for potable-water products. Use only reinforced hose in pressurized water systems, either PVC reinforced with polyester, or steel or vinyl reinforced with nylon braid. While many potable-water hoses are clear, opaque hose has the advantage of limiting slime growth. Covering the ends of the hose with masking tape until the system is fully assembled helps keep contaminants from entering. Other than the normal signs of hose deterioration, slime buildup, discoloration, and poor-tasting water can also signal the need to replace hoses. If your hoses are 10 years old or more, the taste of your fresh water will likely improve if you replace them.

LPG & CNG Hose: Flexibility And Low Permeability

Photo of a propane hose

Leaks in a liquefied petroleum gas (LPG) system (also called propane) can be catastrophic, which is why propane hoses must have permanent connections and cannot be hose-clamped to a barb like other hoses. LPG hose is thermoplastic and sold in specific lengths with fittings already attached. Chafe is the enemy here, and the hose should be protected wherever it passes through a bulkhead. Inspect all your LPG hoses and replace any showing signs of wear including chafe and worn or loose end fittings. LPG hose must be marked "UL 21." Not too many boats carry compressed natural gas (CNG) today, but if yours does, don't use LPG hoses. CNG hose is designed to withstand much higher pressures and must meet the requirement of NFPA 52 for automotive hose. The useful life of LPG hose is considered to be from five to 10 years — if yours is older than that, you should definitely replace it.End of story marker


Beth Leonard is the technical editor for BoatUS and the editor of Seaworthy, the BoatUS Marine Insurance publication dedicated to keeping you and your boat safe on the water.


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