Why are the mutineers destroying the jolly-boat?

The mutineers are destroying the jolly-boat to eliminate Jim and the others ability to use it.

I lay for some time watching the bustle which succeeded the attack. Men were demolishing something with axes on the beach near the stockade—the poor jolly-boat, I afterwards discovered. Away, near the mouth of the river, a great fire was glowing among the trees, and between that point and the ship one of the gigs kept coming and going, the men, whom I had seen so gloomy, shouting at the oars like children. But there was a sound in their voices which suggested rum.