No as the reference is to the Corvus that Rome utilised against the Carthaginians, most boarding would just be people jumping onto the other ship, The Romans decided to drop a whole bridge on them and board that way instead. But the corvus did pose a risk to the ships safety due to it unbalancing the vessel, so I would expect the boarding ship to be more fragile in some capacity. I quite like this as Civ bonus, it is very distinctly Roman, and as far as possible I would like to see this for all civs, things that are distinct and defining for that civilization.