[gurps] Monsters on a water world?

[Onno Meyer]

The TL10 fusion-powered vehicles are fast enough to evade any 
reasonable animals, and they carry enough sensors to find 'em
in time. But what about smaller or lower-tech craft?

* In a post-apocalyptic waterworld setting, humans are a real 
  threat. 
* On a science-fictional waterworld, the top predators will be
  aquatic, and at first they won't know boats are inedible. 

I'm thinking of a spring-powered bolt thrower to represent a 
jury-rigged harpoon gun for a relatively low tech boat. High
tech could be an electromag grenade launcher with SAPHE.

Tom, have you developed the fauna for your world?