This article is one of many floating around right now about the Japanese being "accused" of sinking a protest boat. To me the word accused makes it seem like maybe they did not do it or they are not admitting it and thus is misleading. Anyways there is as expected dispute over the incident and the Japanese doing it intentionally or could not prevent the collision, but there is not denying they caused the boat to be destroyed and sunk.
The incident involved the Japanese Shonan Maru No. 2 colliding with the protester's Ady Gil. The Ady Gil was cut in half by the collision, but fortunately all 6 on board were rescued, although one ended up with broken ribs.
From what I have seen of the show it would seem that they might have purposely been in front of the ship and challenged it. Sure the Japanese should have turned and they very well probably tried, but the activists are probably just as much at fault. Of course, I really have not a clue about what really happened and the news at this time does not shed much light with it being so much on the activists side. By the way I am on their side as far as their views on the Japanese not killing the whales, but it seems the Japanese side is at least not published in English much.