Rule Mixup?

[RobKamm]

On DF11:31 the Water Blaster water elemental has an attack with Double Knockback. In the text it says that:

Originally Posted by DF11

roll 6d as crushing damage, and determine knockback, then double the distance...

B104 says that Double Knockback:

Originally Posted by Basic Characters

lets a crushing or cutting attack inflect twice as much knockback as usual.

I'd always interpreted Basic to mean that with Double Knockback the damage was doubled (in the example of the water elemental 6dx2) and then Knockback applied. Have I been wrong all this time?

It makes a big difference in an upcoming game, my PCs are likely to attempt a lake crossing in a raft with a hostile water elemental trying to prevent them from getting across. If they build a small raft (HP 58 according to LT139, knockback threshold 56), and it gets hit by the blaster the maximum damage is 36 points - insufficient to cause a single hex of knockback. If the damage is doubled (as I had thought) then the maximum is 72 which could knock a raft about enough to force some control rolls.