Tuna Advice--Please!

[Sweetwater]

I've dropped two BFT (estimated 55" to 60") and was hoping someone could give me some advice. Here's the most recent situation.

Hooked both fish solid, got the guy in a fighting belt and harness, put him in the front of the boat (19' CC), clamped the drag down all the way (20 lb pressure rated drag), and let the fish fight the drag and pull the boat. Got the fish to the boat several times, but each time, just out of gaffing range, the fish sounded. So I motored the boat away from the fish to get a better fighting angle. Each time we were able to turn the fish, and it followed/chased the boat and we gained line....only to have the fish sound on us again at the boat.

Eventually we lost the fish when it ran under the boat and nicked the line on either the hull or bow rail which broke the 80# braid.

I'm new at this tuna game and would like any advice about fish-fighting and boat handling techniques from a small boat.

BTW, the rod handled the fish nicely though the reel drag (Saltist 50) could be a bit under powered for these fish. But I'm told my set up should handle fish to 150 lbs and other guys are landing similar fish on spinning gear. Thanks for any advice.