Whoever or whatever or it is, it's strong. It strikes the boat again, this time from the other side. For some reason your teeth hurt. It takes a moment to realize it's because of that sound.
It's like a dozen long-nailed hands trying to scrape the paint off the boat. It echoes throughout the cabin, and you're not sure if it's getting louder because there are more hands, or because they are clawing more fiercely at the wood.