Opening 95L water tank

[philg71]

My Beneteau has these blue plastic water tanks with red access hatches. But mine are totally stuck. How can I open them?

[Pandor]

Get a pair of channellocks and a pipe. Place the channellocks handle ends in one of the slots and use the pipe to leverage between the two hanfles and open it up

[tkeithlu]

Did that do it?

It looks like you've tried breaking it loose with a rubber mallet and a socket wrench extension. The difficulty with that approach is that everything here is springy; the tank itself, the plug, and the hammer, so you weren't really applying much torque.

Another way to get the torque you need would be a wooden screw driver - think of a wooden blade that will fit in the slot in the plug, plus a handle or side bar that will let you twist it while bearing down on it to keep it from slipping.

It's constant torque situation, not an impact situation.

[Cheechako]

Make a board that fits the slot perfectly, Maybe 1 ft tall. Then use a big crescent wrench, pipe wrench or whatever to turn it while you press down into the slot.
When you close it up again, wipe some lanolin sparingly on the threads/oring.