Add becalming and-or getting lost at sea and I think you've pretty much covered it.
Not really; in that a ship that could stand up against creatures like this would likely end up too heavy to move at any speed.
Other than that, the only way to beat creatures like these is to outrun them. Some settings have the fast clipper-ship era sail tech available, others don't.
Then again, in the game I play in our PCs recently acquired* a ship that came with two actual cannons on board; along with crew who know how to operate said guns and who we now have under contract to our adventuring company.
* - we can be a bunch of pirates when we want to be; it helps that one Elf PC has a centuries-long backstory as a supposedly-famous pirate that few people have ever heard of.