Quote Originally Posted by factotum View Post
Of course, if you create a ship which is essentially unsinkable using your available weapons technology, and you can't develop any way of defeating them, you'll probably find other ways around the problem--e.g. you'll build your vessels to be small and fast so they can evade the lumbering "turtle" ships rather than try to fight them, and all battles between big ships would devolve into boarding actions.
As far as I'm aware, Turtle Ships weren't much slower, if at all, than their Asian contemporaries. They're a bit less manueverable, but trading in a bit of maneueverability to be boarding proof, so Cannon resistant to basically be Cannon proof and small arm proof is worth it.

I'm not sure how fire resistant they were, but there was a fair amount of metal so getting it to catch may be an issue