#dreadnaughts

Each Stormraven Gunship can securely carry a squad of battle-brothers within its hold and a Dreadnaught in the magna-grapples beneath its hull. While this spectacle might look bizarre to enemies on the ground...

Kuat Drive Yards Eclipse-Class Star Dreadnought

The qunari are the only culture who have the knowledge of gaatlok aka black powder aka gunpowder, and as such, their dreadnaughts have canons. From the codex entry:

They pulled alongside, their great ship twice the length of ours, and we drew steel, ready for them to board. Instead, a great series of blasts rocked the waves, spewing smoke everywhere. Iron balls the size of a man's head flew as though fired from a bow. They ripped through hull, mast, and sailor alike; our ship came apart like a child's toy. I'd have died in the water had a trading ship not come by to investigate the wreckage.

The Tevinter crew assumed the qunari would board, and were taken off guard by their canons. So I think it’s safe to assume that most naval combat is a matter of ramming and boarding. Unless it’s against a dreadnaught. Then you’re just done for.

The dreadnaughts are also equipped with harpoon guns, as shown in Those Who Speak #1:

Bogga the Hutt's Modified Core Galaxy Systems Dreadnaught "Enforcer One"