If the only thing in there is "sticky sludge" that adheres to the walls of the tank, then it is important, but not probably not urgent.
If there is a significant amount of water, or other liquid that is NOT fuel then you have an issue both important AND urgent.
I am not sure of the piping on the 54, but on a SM you can extend a small diameter hose straight down the diesel fill pipe, and use a hand pump or vacuum oil extractor to get a sample from the very bottom of the tank. If that is clean, you are (most likely) safe for now. If you get a sample that contains water, or anything other than clear fuel, you'll need to get as much of it out as you can.
The easiest way to do it is to hire a tank cleaning specialist to do the dirty work. They are available in most places with a high concentration of large boats, and are usually mobile services mounted on a boat. Short of that resource, I have used a manual oil change pump to suck fuel from the bottom of a tank, put it through a good, clean, water separating filter funnel, and put it back. Keep doing it until no more water or "sludge" comes out.
Have lots of primary fuel elements handy, and monitor them closely until you can get the tank professionally cleaned.
My old boat got its first real tank cleaning as it approached the ripe old age of 40, so if you keep clean fuel going in, you'll get clean fuel out for a long time!
Fort Lauderdale, FL, USA
---In amelyachtowners@..., <sharongbrown@...> wrote :
Out Amel 54 is 10 years old, and the fuel tank has never been cleaned. I noticed today from the dip stick gauge that there is a coating of sticky sludge at the bottom off the tank. I have no prior experience of treating this, and am reluctant to try while we are on a mooring buoy. I would appreciate ny advice on a) if this should be addressed urgently and b) how best to do it.
Ya Fohi, Amel 54 #98