Question: I recently brought my 10-year old boat in for service and the service technician told me that some of my marine fuel hose lines were cracked and in need of replacement. So, I authorized the dealer to replace the lines as they saw fit.

The new hose is marked not only with the USCG A1-15 rating, but with ratings designated by the EPA, SAE, and ISO.

The new hose is marked not only with the USCG A1-15 rating, but with ratings designated by the EPA, SAE, and ISO.

One of the things I noticed as I was looking things over after I picked the boat up was that the labeling on the fuel hose had some new designations on it that were different from the ones on the old hose they replaced. What exactly do the USCG designators mean on fuel hose, and does it make any real difference?

Answer: Excellent question, and yes, it certainly could make a difference what fuel hose you use, depending upon the location on your boat. The U.S. Coast Guard addresses fuel line requirements in the code of federal regulations (CFR) that applies to recreational boats: CFR Title 33. The regulations address in great detail issues related to gasoline fuel systems. The new designator, Type A1-15 describes hose that is less permeable than your old hose, which was simply rated A-1. The photo above shows that array of new cryptic marking that is required on all fuel hoses used in gasoline fuel system on boats. Besides the USCG designation, you can also see some EPA, SAE, and ISO designators. All of these designators are intended to address requirements existing in the global marketplace. Here in the U.S., the USCG designator is the one you need to focus on.

Marine-grade fuel hose is much heavier than the same inside-diameter hose as used in automotive applications. This is done as part of its fire or flame testing, a requirement under the regulations. All fuel hose used in engine room spaces on board gasoline-fueled boats must meet a 2.5-minute fire test rating.

The EPA weighed in several years ago, and the new A1-15 designation is addressing the permeation rate for the hose.  This is all a part of the new, much stricter evaporative emission requirements now in place for all newly built gasoline-fueled boats.  The American Boat and Yacht Council (ABYC) also addresses this in its H-24, Gasoline Fuel System Standards, which essentially mirror USCG and EPA requirements in place today.

So, by design, your new A1-15 fuel hose is rated to a maximum vapor permeation of 15 grams per square meter in a 24-hour period. This compares to a maximum vapor permeation of 100 grams per 24 hour period for your old hose. This represents a significant reduction in the amount of fuel vapor that can actually migrate through the hose. Hose with this rating is acceptable by the EPA for all applications on board.

An important nuance found within the H-24 Standard is the difference between type “A” and type “B” hose. The type B hose is not fire tested, and should only be used in non-engine room spaces.