I was reading this article about this person's boat capsizing and self-righting afterwards. I am not much of an sea/ocean expert, so can someone explain why and when these boats capsize, they don't sink. I would imagine that they need to be kept very watertight. Looking at some of the photos on the Vendee Globe website, these boats look to be a fair size and look like they would sink if the capsizing does any damage to the integrity of the boat's structure.

Sailing alone for 46 days in the gruelling Vendée Globe round-the-world race, Mr. Hatfield's boat – the lone Canadian entry in the prestigious contest – capsized in heavy seas off Tasmania. Mr. Hatfield spoke to The Globe and Mail by satellite phone en route to Australia for repairs on his damaged boat. Here's how he described the experience:

Full news article here.