The Chasm is an interesting ship to say the least. Although equipped with a level 9 weapon, it doesn't seem to do as much raw damage as the Tundra, owning to the fact that shockwave weapons do TONS of damage to a single object (but the mechanics have been changed at 1.06 #473 Shockwaves only 'hit' a single object a maximum number of times), whereas the positron cannon is really good at piercing shields and armor.
|Tharsis plate X4|
|Cydonian shield generator|
|Ares positron cannon|
The Chasm isn't a terrifically hard ship to destroy, you just have to be prepared to either dodge the shots if your shield can't handle it (and seriously think about if you're ready to be messing around in the Outer Realm) or let your shield take it and just focus on taking down the chasm. An unusual quirk about its weapon is that the way the exhaust is drawn is a bit off, resulting in some confusion as to where the shot is going. For further reference, the FIRST yellow dot is the shot, and the rest is the exhaust.