While it may not be the elusive and slipper Nisshin Maru, the Yushin Maru will simply have to do. It's still a big get for the Sea Shepherd. After all, their 'Whale Wars' (Fri., 9PM ET on Animal Planet) is to cripple the business of whale killing by Japanese ships, and the Yushin Maru is an important cog in the machine.
To attach a prop fouler, which is supposed to jam up the propellors of the ship, they must get very close to the prow of the vessel they're trying to jam. In this case, their much smaller boat got a little bit too close and took a solid hit.
Luckily for all onboard, no one was hurt and they can just chalk up the jarring moment as another memorable experience on their quest. Even more importantly, they were able to get close enough to disable the ship, at least temporarily. It may not be "the white whale," but it still must be pretty satisfying.