Time to pay attention to your boat hoses
Time to pay attention to your boat hoses
Your boat is full of hoses for many different purposes, many of them critical to essential onboard functions, and even keeping your boat afloat. Make sure they are fit for purpose, says Dag Pike
Look inside your vessel's engine compartment, and you will notice a network of boat hoses in various styles and colors, writes Dag Pike.
The same will be true if you lift the boards giving access to your bilges.
Boats rely on hoses not just for functionality but also for buoyancy, making them one of the most vulnerable parts of the boat.
Each hose in the boat should be part of your annual inspection. They also need replacement every ten years.
When boats sink at their moorings, hose failure is often the culprit. If it happens at the mooring, consider yourself lucky.
At sea, hose failure can be catastrophic. Many owners don't realize that numerous hoses on their boats are exposed to seawater.
Regular hose replacement is ideal for reliability. But how do you check your hoses during an annual refit?
One effective method is to squeeze them. If they feel mushy, crumbly, or overly hard, they need replacing.
Next, examine the connection points. If the hose is swelling around the securing clips, it has probably reached the end of its useful life.
Don't be tempted to think it will last another year. For peace of mind, replace the boat hose.
Hoses are used to transport liquids around the boat. Due to the different types of liquids used, it's vital to select the correct hose for the job.
No multi-purpose hose exists. Special hoses are needed for applications such as engine exhaust, engine water inlets, hot and cold domestic water supplies, sanitation pipes, fuel, bilge pumps, and hydraulics, if applicable.
A complete hose replacement can be challenging and expensive as specialized boat hoses are costly.
A full hose replacement is best left to a boatyard, but you can replace one or two if they look worn.
Boat hoses: Engine
One critical hose in the boat brings in raw seawater to cool the engine.
This hose must be flexible due to the engine's flexible mounting.
A failure in this pipe would cause the engine to overheat and flood the engine compartment. Seawater is also injected into the exhaust system to cool the hot gases.
Without cooling water, the exhaust hose could catch fire.
This cooling water pipe needs reinforcement with either stainless steel or semi-rigid plastic coil and must be a heavy-duty hose you can't compress by hand, to withstand the seawater pump's suction.
Cutting it can be tough if it has a metal coil and securing it requires double worm drive clips.
Ideally, it should also be a fireproof hose.
Most other engine hoses are from the manufacturer and should only be replaced with proper engine spare parts. However, the flexible exhaust pipe at the engine's other end is crucial.
This pipe must withstand significant pressure, reinforced with wire, and capable of handling temperatures up to 250°C. More expensive silicone-based hoses can withstand even higher temperatures.
Boat hoses: Fuel
In the engine compartment, you'll also find fuel hoses.
Many fuel lines are metal, but flexible sections are needed to allow for engine movement.
Any flexible sections should be made from approved material suitable for the fuel you use. Standards for petrol and diesel fuel lines are very high due to the fuel's nature; they should also resist fire for a limited period, allowing you time to escape during a fire.
Gas hoses
High standards are also required for any flexible sections if you have a gas supply for the cooker.
They are usually orange, marked with BS3212/12 or EN 16436-1:2014.
The hose will begin to deteriorate as soon as gas passes through it or where it is exposed to UV from sunlight. Also, in the engine compartment, you'll find bilge pump piping from the pump to an overboard outlet.
The bilge pump piping should have a smooth interior bore so that water flows easily. The piping routing, like most onboard, should avoid sharp bends that might restrict flow.
Avoid any loops in the piping which again can restrict the flow.
Bilge pump piping is usually reinforced with metal or plastic spirals to maintain its shape and prevent kinking.
Domestic water hoses
For domestic hot and cold water supplies, boat builders often use semi-rigid piping like the type used in homes, which works well if secured properly.
Different materials are used for hot and cold water pipes, so ensure you get the right one. Drinking water pipes need approval for this purpose.
The temptation might be to use cheap, clear plastic piping, but it tends to get brittle over time and is unsuitable for hot water.
Vinyl is a common choice for water hoses.
Sanitation hoses
Like bilge pump piping, sanitary piping shouldn't have internal corrugations because a smooth waste flow is required.
Carefully plan the flow to avoid waste sitting in the pipe, which can cause smells to permeate through the plastic.
Hydraulics
Hydraulic piping needs to handle very high pressures. They are usually standard types used both onshore and afloat, with metal fittings that tend to corrode. A smear of grease might prolong their life.
Fitting of boat hoses
Finally, any piping connected to a skin-fitting must be reinforced because if the pipe fails, the boat will sink.
A hose suitable for this job shouldn't be squeezable, unlike car radiator hoses.
This semi-rigid hose can be challenging to fit onto the skin-fitting. You might soften it by immersing it in hot water before sliding it over the hose tail.
Ensure you get the right size hose for the fitting and resist using a slightly larger hose, as it will easily slide over the spigot.
Boat hoses are measured by their inside diameter, so check for a suitable quality marking on new hoses.
Do not skimp or compromise on the quality of a replacement hose—your life may depend on it. Pay attention to what the hoses are attached to and how they are attached.
Corroded or rusted hose clamps should be replaced. There should also be two hose clamps on any pipes connected to an external skin-fitting to prevent sinking.
Similarly, with skin-fittings, remove the hoses occasionally to inspect the hose tails and the overall state of the skin-fitting.
Signs of boat hose trouble
- Hose past printed expiry date
- Signs of weeping or porous material
- Cracking or perishing
- Crushed, kinked, or constricted
- Calcified with restricted internal diameter
Marine Sanitation Hose Test
There is simply nothing like the smell of the sea. Unfortunately, a boat with defective sanitation hose smells nothing like that.
Link to MIC
Additional reading:Questions You Should Know about special shapes rubbers factory
Sanitation hoses are designed to contain odorous gases, unlike similar-looking hoses used for fuel, coolant, and tap water, which are not interchangeable.
In a 2000 study, Practical Sailor used carbon disulfide as a sewer gas substitute, revealing that SeaLand's OdorSafe Plus hose performed best.
Despite this success, some synthetic-rubber hoses that usually perform well failed. For example, Trident 102 is known for reliability but failed in that test. Shields also found their hose failure surprising.
Given carbon disulfide’s role in rubber production, was the test unfair? Practical Sailor repeated the test with diluted chemicals and vapor, yielding similar results but never correlating these with real waste performance.
A year ago, a new long-term waste hose test began using actual sewage from a 20-pound iguana. This article highlights the various hoses and materials being tested, with preliminary results available after one year.
A Look at Hose Materials
The builder of Drew Frye's catamaran placed the holding tank and sanitation hoses in a bulkhead compartment isolated from the rest of the boat. Unfortunately, clear vinyl hose was used for the vent lines, which didn't resist permeation, turning yellow and sticky with foul residue. Ordinary reinforced exhaust hose was used for sewage and pump-out lines, which also performed poorly.
Over time, dried permeate left a brown residue, making the compartment foul and unpleasant for retrieving stored items. A reinforced fuel or coolant hose, no matter how well-built, can’t contain sewage stink for long periods. On a boat, flexible materials should be durable.
Boat owners should look at urethane, butyl, EPDM, and PVC hoses for sanitation systems instead of nitrile and neoprene, used for fuel and exhaust hoses.
PVC pipe is rigid, and vinyl hose’s plasticizers make it porous, allowing acid gases to seep through quickly. Soft vinyl tubing fails within months.
Butyl rubber, used for inner tubes and laminated tire liners, has low gas permeation rates but poor oil resistance. Properly used, sanitary waste doesn't contain oil. However, disposing of oil or solvents in the head can damage any sanitation hose.
EPDM is common in steam and high-end engine coolant hoses due to low permeation rates with hot water and antifreeze, but is weak against oil.
Polyurethane has a good combination of chemical resistances, including oil, though its air and steam permeation rates are higher than butyl and EPDM. It's common in hoses used by honey dippers. Shields combined it with other polymers in a composite hose.
What We Tested
We tested flagship sanitation hoses from four leading manufacturers: Trident Marine's 101/102 EPDM hose; SeaLand's OdorSafe Plus, a PVC and acrylonitrile butadiene rubber hose; Raritan's butyl rubber Sani/Flex Odor Shield; and Shields Marine's Poly-X polyurethane sanitation hose.
For comparison, we also tested schedule 40 PVC sanitation pipe and Trident's clear vinyl hose. PVC pipe is known to resist permeation indefinitely, while clear vinyl hose was included to highlight its expected failure in marine sanitation systems.
How We Tested
We created six miniature holding tanks using 5-gallon buckets with lids containing sanitary waste from a 20-pound iguana. Seawater was used for flushing as it results in more severe odor problems. The tanks were dumped each time they reached 80% capacity.
Each tank had a hose continuously filled with sewage. Although manufacturers recommend avoiding hoses submerged in sewage, they agreed the method was valid to force failure. Proper installation advice includes sloping lines toward the holding tank and clearing the line with water after sewage, which we ignored to force failures.
We also tested hose flexibility using vertical deflection and bend radius measurements at 65 degrees, revealing temperature impacts on stiffness and flexibility. Temperature significantly affected the OdorSafe hose, making it less workable below 50 degrees and effectively rigid at 40 degrees while softening rapidly with heat.
When it comes to waste hoses, only one measure matters: whether the vent stinks when flushed. We used a hydrogen sulfide monitor to support sniff tests, and none of the premium hoses showed significant odor permeation during the initial one-year test.
Testers will continue for several years to identify the best, most durable waste hose for onboard use.
SeaLand OdorSafe Plus
SeaLand's OdorSafe Plus, the only PVC-based hose in the test, is highly regarded but very stiff. Installing it often required gentle warming. It received positive marks for its smooth finish and cleaning ease. The hose showed no signs of permeation after one year, making it a strong choice for installations with adequate space.
Trident 101/102
Trident Marine's 101/102 EPDM hose, known for a reliable track record, was easy to install despite being prone to picking up dirt. It had a distinctive "new rubber" smell, but this was not a significant issue. Available in various sizes, it becomes the Budget Buy pick for its dependability and affordability.
Shields Poly-X
The costly Shields Marine Poly-X hose received high marks for odor resistance, cleaning ease, and installation flexibility. Slightly less stiff than OdorSafe, it is the Best Choice pick for installations requiring high-quality, easy-to-clean hoses.
Raritan Sani/Flex Odor Shield
Raritan's flexible Sani/Flex Odor Shield is easy to fit, making it suitable for tight spaces. Careful installation is necessary to avoid kinking. It remains a Recommended product after one year of testing.
Trident Clear Vinyl Hose
Trident's clear vinyl hose, included for comparison, failed after four to six months and should not be used in marine sanitation systems. Other brands of vinyl hose also performed poorly.
Conclusions
No premium sanitation hose showed significant signs of permeation after one year, except for clear vinyl, which is unsuitable for marine applications. The stiff OdorSafe Plus is recommended for spaces with enough room, and the flexible Raritan Sani/Flex is ideal for cramped installations. The budget pick is Trident 101/102 for its affordability and ease of installation, while the premium Poly-X is the best choice for high-quality, easy-to-clean installations.
Stay tuned for updates as we continue this long-term test.
Sanitation Hoses
Installation Notes
- Sanitation Hose Test
Tips & Techniques
Contact us to discuss your requirements for marine sanitation hose. Our experienced sales team can help you identify the options that best suit your needs.
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