Well, I think part of the reason is that we never see fleets actually used in that fashion because we never see any naval-to-naval combat in the series at large. Major fleet action is at the Battle of the Blackwater, but that’s not vessel-to-vessel combat, and the only real exclusively naval battle is Fair Isle, which we never get a full description of, though I believe it to be remarkably similar to the Battle of Salamis. The upcoming battle off the Isle of Pigs looks to have some supernatural mojo taking place which is going to be a far different beast entirely.
Commonly, the ships that the royal fleet would be facing would either be Ironborn or Essosi pirate vessels. Against the smaller ships of the ironborn, missiles would be great, but burning pots of pitch and thatch would be even better, as would using the larger size and bulk to their advantage. After all, longboats really aren’t useful prizes to the royal fleet, save perhaps as wood for repairs, so just punching a hole in the boat and leaving the ironborn to drown would be good enough. As for pirates, well, a large pirate warship like the Valyrian would probably face more conventional galley tactics.
Thanks for the question, RSA-Fan.
SomethingLikeALawyer, Hand of the King
I find this confusing – we’ve seen ships crowded with archers and siege engines, we’ve seen boarding parties, what are you missing?
Also, with longboats, you don’t even need to ram them to sink them. They’re so low in the water compared to a galley that a galley can simply swamp them by sailing right over them.