The provisions of this section of Part 2 in the BSS Standards are mandatory for non-private boats where applicable.
Spilling fuel into your boat means there is a risk of fire or explosion if that fuel or fuel vapour becomes ignited. To reduce this risk the filling point must not let any fuel spill into the boat, including the bilges. Three examples of how to achieve this are shown above.
Inside a confined space even a small amount of potentially flammable fuel carries a serious risk of fire or explosion.
Small amounts of fuel can be diluted if they escape overboard. If large quantities of fuel or other substances escape into a watercourse you should contact the Environment Agency Pollution Hotline on 80 70 60 (24hrs) or the Scottish Environment Protection Agency on 73 72 71.
To make sure that any fuel filling nozzle is properly inserted and to prevent 'blowback' of fuel when refuelling, the fuel filling system must have an internal diameter of at least 31.5mm (or 11/4 ins). It is good practice to use a fuel filling system with a larger diameter since this further reduces the risk.
To stop a flexible filling hose from collapsing if it's bent, which could cause blowback or a leak, the hose must be of a strong, non-kinking material which is not easily compressed or squeezed. This is particularly important if the hose needs to be bent at an angle when routed from the tank to its deck connection.
All flexible hoses perish over time as a result of the hose material reacting with the fuel. To minimise leaks the fuel filling hose must be made from a material that's suitable for the fuel that it carries.
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If the filling hose is not marked as being suitable for use and you don't have relevant evidence from the supplier confirming its suitability, it's recommended the hose is replaced with a fuel filling hose complying with BS EN ISO , SAE J or DIN .
To help prevent fuel leaks, the filling hose or pipe must be connected with leakproof joints between the top of the tank and the filling point. Care must be taken when using worm-drive clamps to ensure they are the right diameter for the hose to maintain a leakproof joint. It's recommended that, during routine maintenance, you check the condition of clamps that are used to make joints. They must be replaced if they appear damaged or corroded.
For additional protection, it's recommended that you use double clamps on a filling hose used for petrol.
To help prevent abrasion damage against interior fittings, filling hoses must be well supported at regular intervals.
Fuel must be able to drain back into the tank and not be retained in the filling hose, since this could cause blowback when refuelling and may contribute to a deterioration in the pipe's condition. The filling hose therefore must be of the minimum practical length and continuously rising between the tank and the filling point.
To reduce the risk of leaks it's essential that all joints and connections must either be seen or felt to check their condition. [2.1] [2.2]
Re fuel remaining in place in some portion of the filler hose, typically rated only for A2 use, that is, to not have fuel permanently in the hose but suitable for enclosed spaces:
I agree that having fuel remain in the horizontal portion of the filler hose than crosses under the deck from the gunwale to the tank filler inlet can be a problem; the permeability of the A2 hose is not designated for having fuel present in the hose continually. For this reason when I am adding fuel to the boat I try to be mindful of this possibility. If we are adding fuel on the water, I try to keep the boat trim so the filler side (the port side on my boat) is raised higher than the other side. You can do this usually by moving a cooler to one side or just sitting on the gunwale on that side.
Once the boat is on the trailer and fuel will be added at a highway filling station, I try choose a pump so that, if there is any grade or slope involved, the trailer is aiming uphill. This helps to get the fuel drained out of the filler. Also, when loading the boat onto the trailer, it could be advantageous to have a slight tilt toward the non-filler side (again, on my boat, the starboard side) so that even when fueling on the highway the fuel tends to run downhill into the fuel tank and not remain in the filler hose.
The worst possible situation with the filler hose is for the hose to develop a dip or low spot in its path from gunwale to tank filler inlet, which then tends to collect fuel no matter what you do while fueling. You might be able to mitigate that problem whenever you get the boat in the water by having a couple of people sit on the other gunwale and get a rather steep list to that side, again encouraging the fuel to flow out of the filler hose. I try to do this when fueling on the water.
The worse situation is to add a lot of fuel for winter storage from a highway filling station with the boat on the trailer. If you then tow the trailer down any sort of big downhill grade, there is a good chance the fuel will move to the forward part of the tank and may rise into the filler hose; it will then sit there for six months of winter storage.
ASIDE: on our old sailboat the fuel tank was located directly below the cockpit deck level. The fuel filler inlet and cap were located on the cockpit deck, and the path into the tank was a straight vertical path. There were two advantages of this: when you added fuel, the fuel flowed directly down a short filler hose and into the tank, so there was no possibility of any fuel sitting in the hose; and, the tank level could be sounded with a stick to get the actual tank level. Because the fuel was diesel, the sounding stick was a smelly old pine dowel that would add a bit of fragrance to the locker in which it was stowed in a small section of PVC pipe fastened to a bulkhead. The other drawback of this arrangement was the location of the filler cap; being on the deck there was always some water sloshing round the deck when you did any cleaning or scrubbing of the deck. The filler cap had to have very good seals to keep the water out of the tank.
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