After sinking HMS Hood, Bismark finishes off PoW, and returns to Germany?

I can't say what the effect on speed would be. Added length is usually associated with increased speed. But the length was added to provide more buoyancy to compensate for all the added weight. I keep wondering about that, with that buoyancy helping with the added weight forward but nothing to compensate for the additions aft. Scharnhorst was a poor seaboat as built; I'm not optimistic about additions being slapped on.