You know the scenario, you head to the fuel dock to fill up with fuel before heading out, and believe that you will be able to control the inrush of fuel from the pump. You think that you'll be able to let go of the trigger in time, so that the fuel won't back up and spoil the decking. But once again you fail and then have to spend the next 20 minutes or so mopping up spilled diesel from the deck using almost an entire roll of paper towels in the process. No one likes to spill fuel, it smells bad, stains teak decking and any that gets in the water leaves a huge slick around the boat. Having owned both diesel and gasoline powered boats I have to say that diesel seems far worse in many ways than gas. Diesel has a predilection to foaming up and frothing all over the teak. The Clean Way Fuel Fill is in essence a baffled air vent which lets the fuel in and the air out. A snug fitting bung seals the fuel deck fill and any blow back foams up into the elongated funnel. Internal baffles prevent sploshing (is that a word?) and the clear plastic lets you easily see when the diesel starts to foam up, contained inside the plastic rather than all over your decks.
I'll admit that the shot above is clearly a publicity photo, but it does show rather well, the Clean Way Fuel Fill from Scanvik marine. I've been trying this out recently, as they rather graciously gave me one to try, and I have to admit that it does work, and work well. By the way there is a video on their website which shows it in action.
I can recommend the Clean Way, it does what it says, keeps the deck clean and prevents spills but there is another, cheaper, way. One trick I learned many years ago is that just before you fill up and remove the fuel filler cap, sloosh (another great word) a couple of buckets of seawater on the deck. Then, if any fuel does leak it will tend to float on top of the water and can be cleaned up far more easily than if it is allowed to soak into the teak or fiberglass.