I would venture to say the acts of these so called activists is pure terrorism. They're purposefully endangering the lives of others in order to force the japanese government to succumb to their demands. They are pointing lasers at the crew, throwing liquids on the decks to make them extremely slippery, crashing with the whalers and so on forth.
I've seen two videos of the crash: one from the whaler and another from an another ecoterrorist boat. By judging from the other terrorist ship's footage they were trying to stage the accident on the whaler and present their video as the single proof of the crash. It's silly to use a million dollar carbon boat for that though, you'd think a cheaper dinghy would've done the same; perhaps they wanted to cash in million bucks from the whaler's company to make a dent on the business.
When looking at the video by the terrorists you may get the impression that the whaler was turning to right to ram the batboat, because the left side of the whaler becomes constantly more exposed. I've also heard that the terrorists have said it turned right to ram their boat. However, the other terrorist ship was crossing the whaler's path from right to left while the whaler was still going straight, until the batboat suddenly throttled up and ran in front of the whaler.
As to why aren't these terrorists jailed is beyond me. They're endangering everyone's life out there with their stunts and besides that also inept seamen. Instead they're nearly hailed as heroes by the press.