From 28 June to 14 July, CANON patrolled its designated area. Ship operations during this period involved the usual Market Time routine of board and search coupled with a few instances of harassment and interdiction gunfire. On 9 July, CANON patrolled the Bo De/Cu Lon Rivers for the first time. Five days later, on 14 July, while on patrol, CANON was ambushed by enemy forces near the mouth of the Bo De River. A rocket hit in the port engine room placed the hydraulic system out of commission, rendering the pitch system inoperative, and CANON drifted aground on the river's right bank. Accomplishing emergency repairs, CANON was dislodged with the assistance of two PCF's and its own starboard shaft and returned to Sea Float. Ordered to Cam Rahn Bay for repairs, CANON proceeded to that port under its own power.
With repairs completed by 27 July, CANON returned to its patrol duties, this time to Market Time Operation Area 8B. Again, routine operations were a matter of course with escort duty serving as a secondary responsibility. On 9 August, CANON returned to the Bo De/Cu Lon Rivers and the next day escorted USS BRULE (AKL-28) to Sea Float. After spending the night as naval gunfire support ship for Sea Float, CANON returned to the river to conduct routine patrol. At 0920 CANON encountered hostile forces for the second time and received fire from both banks of the river. The crew responded quickly and inflicted heavy damage on the enemy, employing both the ship's main armament and small arms fire. This action by the enemy resulted, in part, in the following:
Eight B-40 rocket hits to port and starboard;
Extensive rocket damage to the bridge;
Fourteen personnel casualties, including the Commanding Officer, of whom five were medevaced.