What makes a 'fast' battleship?

[generalvikus]

I always understood that a battleship needs to have a speed of at least 27 knots in order to be considered 'fast' and therefore be given preferential treatment by the battle generator. But this raises two questions: firstly, what if the ship is designed for 27 knots but fails to reach its design speed? Secondly, what if it originally makes 27 knots, but falls below that speed over the course of its service life? This is of considerable importance, because a ship may commonly lose two knots of speed over the course of its service life, so a margin of safety which accounts for that and failing to meet the design speed would put the minimum speed for a 'fast' battleship at 30 knots - even with the realistic speed mod, considerably more expensive on any displacement. Does anyone know the answer to these questions?

[dman1791]

I seem to recall reading somewhere else that age-induced speed loss does not change whether you get an FBB, but the trouble reaching design speed event might. Aging causes loss of speed that is presented differently (speed in parentheses), while the event seems to actually change the design's listed speed entirely, including in the rebuild menu.