) because of those chains, it's almost one of the first things I learned when we bought a boat with a deck fill anything.
The replacement is not a cap, it is the entire deck assembly, including the hose connection. It is all stainless steel, not the amoit aluminum casting. Better part.
They can't find him the cap. From some other forums it is not uncommon to lose the cap. Apparently these also use a special wrench to open.
So you had to unclip the chain after you opened the fitting to allow the hose to fit?
As former mobile pumpout service owner, I can tell you I only wish this was the case.
The chains don't unclip. They are screwed to the cap and interior of the deck fitting. When we came across these in my business, we would unscrew or actually break the chain, letting the loose end hang down inside the fitting. Because, yes, the chain interferes with pumpout hose nozzle.
These caps are not restricted to Beneteaus only, but I can tell you I've come across those that have them.
This is what you get for your $45 USD + shipping - the cap AND the thru-deck. Beneteau also sells a short little spanner (wrench) to unscrew the cap, one end fits the waste and water, the other end fits the fuel cap. I have had to replace two of these caps because an inexperienced hand decided to use the full leverage potential of a winch handle to permanently attach the cap to the thru hull.
since I prefer boats designed and made by Americans.Yeah, it's called a "winch handle."
But on some forums I saw they used a special wrench as a winch handle did not fit. Apparently there are a couple of sizes. But hey, if you like the French designs, it is your money. 
