Our sub's been cruising urgently for a good while, under heavy strain. The Captain calls "East!" The Engineer dutifully crosses off the last remaining bubble in the East panel -- but it's also the last nuke bubble. Does the ship suffer two damage (one from filling every bubble in the East panel, plus one from filling in every nuke bubble), or just one?
I sort of agree with fastattaq. However, I wouldn't erase the whole board.
I'd erase one of the two possible options (either the entire directional column, or all the reactor symbols). Then, I'd deal the sub one damage for filling up the section (or reactor symbols) and erasing it.
I could also see ruling it as erasing both all of the reactor symbols and the entire column and dealing the sub two damage.
It all depends on how harsh you want to be. However, the first ruling seems harsh enough to me, since you still have a bunch of symbols in one area that are threatening damage and will have to surface soon anyway.