Rogue Galaxy Quarry: The Steel Shipwright
You will want to buy a Cyclonic Pump from Bivine who is in the same room as the ? circle. He's located in the north eastern part of the room, when you come in from the teleporter you just have to ride the lift on over. After you buy the pump ride the lift to the central boat hop on and use the pump at the ? to initiate the fight.
The fight itself is pretty straight forward, he is one of those mobs where you have to constantly jump in order to hit him in the face where he is vulnerable, this is extremely annoying but he doesn't have many strong attacks. Just try not to get knocked off, I didn't fall off so I am not sure if you'd totally screw yourself or what. That said, I didn't even come close to getting knocked off, I totally rolled the boss and barely even had to heal. Jaster was 38 at the time for me.