Does anyone know what a block spanner is and where I can get one?
According to my manual I need one to drain my seawater system as I can’t budge the drain point in the picture below and it is in a right sod of a spot.
A ring spanner or a long socket worked for me.
It's doesn't have to be mega-long, just long enough to get a decent grip on the drain plug without fouling the nipple.
Mine required a fair amount of force: I don't think it had been opened in years :ambivalence: