The Most Overlooked Safety System on Your Boat? Your Hoses

There is a longstanding joke in the marine world that any product with the word ‘marine’ on the packaging creates an excuse for charging double the price versus an identical non-marine product. I can think of nowhere on a boat that this is more evident than marine hoses. But, as you'll see, this is one case where there's good reason for it.

Hoses are everywhere on boats: fuel, exhaust, scuppers, engine water intake, potable water (hot and cold), waste, water heaters, bilge water, gear lube, and blowers. It turns out that ‘marine grade’ is actually quite important for vessel safety. The ABYC (American Boat and Yacht Council) sets standards on many of these hose types in order to keep vessels seaworthy and boater safe. If you’ve had a survey done recently, you may note that any hose and clamp recommendations are referenced to specific ABYC standards.

There are many reasons why these standards exist. This article could be full of horror stories: garden hoses used to replace fuel lines, flooding due to collapsed hoses and carbon monoxide leaking through substandard exhaust hoses. But, we're going to educate instead.

Lets examine each hose application.

1) Fuel Lines

Fuel hose construction is based upon fire resistance and permeability - highly important for applications aboard, especially with gasoline. Hoses that pass a stringent ‘two-and-a-half-minute burn test’ are classified as Type A; hoses with slightly less fire resistance are classified as Type B. In addition to fire resistance, the permeability of gas vapour through the walls of the hose is a concern. Hoses that pass the more demanding test are Class 1. Hoses that have a higher permeation rate are Class 2.

Because of this, we end up with 4 classes of hoses: USCG Type Al, USCG Type A2, USCG Type B1, and USCG Type B2.

To qualify for any of these categories, the hose designation, date of manufacture, and the name of the manufacturer (or a registered trademark) must be written on the hose. Otherwise, it is not legal in those systems: primarily inboard gasoline engines, and inboard/outboards that must comply with these regulations.

The regulations state that for inboard gasoline engines and inboard/outboards, any hose run as a fuel line between the fuel pump and the carburetor must be classified as Type Al. (Type B1 may be used on systems with anti-siphon valves). Vent and fill lines must be type A1 or A2.

ABYC H24, Gasoline Fuel Systems requires Type A2 hose on all fill hoses inside engine compartments. It also covers outboard motors (requiring B1 or better hoses). ABYC H33, Diesel Fuel Systems is a standard that covers to inboard diesel engines, and includes a modification that allows any of the four classes of hose to be used for fill and vent hoses.

Fuel hoses are typically slid onto a metal fitting - a hose barb - and secured with a hose clamp. Double clamps are required on fuel-fill pipes, each with a minimum band width of 1/2". ABYC requires the clamp to be "beyond the flare or bead, or fully on serration where provided, and at least 1/4" (6mm) from the end of the hose.

Fill pipes are required to have a minimum 1 1/2" inside diameter; vent pipes a minimum 9/16" inside diameter. ABYC states that they must be self-draining (not normally full of fuel)

2) Exhaust Hose

Exhaust hose requires a heavy-duty, fabric-reinforced construction. ABYC standards requires that the hose be able to withstand a total loss of cooling water for two minutes with the engine running at full power, and still not suffer a loss of integrity.

Exhaust hose comes as hard wall (with wire reinforcement), or soft wall (no reinforcement). Hoses that are longer than 4-6 times the inside diameter of the hose, or with tight curves are wire reinforced for added support - this prevents the hose from kinking on bends, sagging on long runs, and moving from the pressure changes that occur in an exhaust.

Exhaust hoses should be double-clamped on all exhaust hose connections, with a minimum band width (for each clamp) of 1/2" in order to minimize the chances of carbon monoxide and water leaks into the boat.

3) Engine Raw-Water Hose

Engine manufacturers usual prescribe heavy-duty hoses for engine installation. These hoses run from the boat’s through-hull to the water pump, and from the water pump to the heat exchanger, up to the engine’s exhaust. Its often easier (and cheaper) to install a light duty rubber hose to add in connections to a hot-water heater in this system, as well.

Although heater hose is generally heat resistant and is adaptable to high pressure, it is thick and soft. Abrasion, heat hesistance, collapse-under-vacuum, and chafe/wear due to vibration are all issues that a good-quality marine water hose (which will be thicker and more reinforced than heater hose) will solve.

4) Potable Water Hose

ABYC and standards state that a potable water system should be plumbed with hose or tubing manufactured from Food and Drug Administration (FDA)-approved materials, with the hoses or tubing so labeled. The FDA, in turn, requires PVC hoses to be manufactured from virgin, rather than recycled, PVC and textile reinforcement. Compliant hoses are stamped “FDA approved.”

5) Scupper and Bilge Hoses

ABYC standards make a distinction in hoses that are ‘below the water line’ – these are hoses that, if broken or damaged, will cause the boat to fill with water, ultimately sinking. Below the waterline hoses include scupper, drains, bilge hoses, and any hoses connected to seacocks. The same hose that’s used for engine raw water hose is often an appropriate choice for cockpit drains, sink drains, and toilet suction lines: These hoses are chosen based on their strength, tolerance to chemicals, abrasion resistance, and withstanding the pressure of suction (in bilge and toilet applications), without collapsing. A heavy duty, fabric reinforced rubber should be used.

ABYC H27 on Recommended Practices and Standards Covering Seacocks, Through-Hull Fittings, and Drain Plugs, calls for the installation of a seacock on “all piping, tubing, or hose lines penetrating the hull below the maximum heeled waterline...under all normal conditions of trim."

6) Waste

Toilet-discharge hose must be of a special impermeable type, generally labeled “Sanitation Hose.” It’s available in PVC and Rubber varieties, and the choice depends on a few factors:

PVC sanitation hose must be specially compounded from a high-density material with a greater than-normal wall thickness, in order to increase resistance to moisture absorption. As a result, it’s quite stiff, and may therefore be difficult to fit tightly to any hose barbs. If the barb is undersized, the clamping pressure needed to seal the hose to the barb will cut into the hose, and cause it to develop microscopic cracks (creating hard-to-trace leaks) at the edge of the clamp. If, on the other hand, the barb is too big, and the hose has to be stretched over it, the hose will work-harden and once again develop microscopic cracks where it has been stretched.

Rubber Sanitation hose is more tolerant than PVC hose of poor hose-barb fits. It also has greater flexibility, and, thanks to its heavy-wall construction, resists permeation much longer.

When installing sanitation hoses-either PVC or rubber, avoid creating low spots that will retain waste.

7) Hose Clamp Installation

A secure connection starts with a correct installation.

Clamps depending solely on the spring tension of the metal shall not be used. All components of hose clamps shall have a resistance to corrosion equal to or greater than 300 series stainless steel.

• Be sure the hose is designed to be clamped. Some Type A fuel hose, and certain wire or mesh reinforced hoses, are not designed to be clamped.

• Clamps depending solely on the spring tension of the metal shall not be used

• Clamps should be resistant to corrosion

• Clamps should be reusable, except:

  • Clamps used with an outboard assembly primer bulb

  • Clamps used with quick-connect couplings

  • Clamps used from the outboard primer bulb assembly to the outboard

• Match the hose inside diameter to the outside diameter of the connecting spud, pipe, or fitting. Fuel hose has actual tolerances on the hose to spud connection.

• Clamps shall be beyond the bead or flare – or over the serrations on the connecting fitting.

• Use the proper size clamp for the installation. Clamps oversized for the hose do not seal properly.

• Do not overtighten hose clamps. Follow manufacturer recommend torque specifications.

• If using double clamps on connections where it is not designed or required, avoid the clamp being placed on the bead or beyond the barb as it can deform or cut the hose and weaken the connection.

8) Maintenance

Even with high quality, properly installed hoses, there is always the potential for an unforeseeable failure. Many boat owners leave crucial seacocks open from one season to another, and never look at their hoses and hose clamps. Regular maintenance and inspection should be done on hoses, clamps, and seacocks. Attention should also be given to the types of fluids that are flowing through the hoses – including the types of fuel (ethanol content), the antifreeze that’s used, and the cleaning, sanitation and deodorizing chemicals that may come into contact with hoses and fittings. #tips