One of my greatest issues with Nemesis is exactly this point. Scimitar is pretty large, and can't maneuver past a certain, albeit respectable, envelope. Once "hit", though, it should have been relatively easy to project course and keep hitting it - each additional hit provides new course information. And setting torpedoes on more of a "proximity" setting (e.g. blow up when you get -here-) would at least guarantee some damage.
Oh well, its all in the writing, we needed a cool crash scene.