So I'm currently running with fore and aft quantum torpedoes on my Chimera. I currently run with use a copy THY2 which I use for hull spike damage. But I'm wondering if there are better options. I was considering going for tricobalt and ditching the THY in favor of another power, but after the change I'm unsure. Any advice? What do people use when they want to do heavy hull damage?

For heavy burst damage on hull, DPB3 + tric mines is the way to go. However for sustained hull damage, and damage over time, Romulan Hyper Plasma Torpedo with proj weapons officers. You get the plasma congo line of death and a burn that can stack up to 15 times. It's quite nice.