Re: the main batteries, en echelon means staggered fore and aft; the port side turret is abaft the starboard turret. Thus the ship is bilaterally asymmetrical in the plan view.
I THINK IT WAS A MINE. IF IT WAS COAL DUST EXPLODING IT SHOULD HAVE BLOWN THE GUNS OFF THE SHIP. AS IT WAS THE MINE HAD OPENED A HOLE AND WHEN THE DUST EXPLODED IT HAD A PARTIAL RELEASE POINT. THE REST OF THE EXPLOSION WENT THROUGH THE FRONT OF THE SHIP.