So, how I've been taming them without a skiff is figure out how many cannonballs it'll take less then or equall to 4 place down four cannons or 3 or how many itll take more then 4 place half the amount down (6 cannonballs/ 3 cannons, 5 cannonballs 3 cannons) load them up find your space whale gain aggro and run straight at the cannons (grappling hook helps for getting to cannons) the fire all as quickly as possible for 4 shots, for more then 4 fire them all (3 for 6 etc) reload and fire again as quicly as possible
Did a test tame on a level 95 on official. Not even 40 rockets knocked it out. Shot it in the head, and by head i mean the very front of its face everytime, about 8 seconds between shots to align myself and aim. Didn't KO. The amount of rockets is wrong.
Hover Skiff makes this easier but isn’t necessary! They aggro very easily to player structures, I got my first one mad at a stone dino gate on the ground. Once it’s stuck to the gate, put a couple cannons down (this is important- they’ll run away faster than 1 cannon in most cases) and put em to sleep. 2-3 cannons and 3-4 cannonballs.