Naval combat attack priorities

[Traveler]

It seems to me that the highest priority target in naval combat should be the carrier fleet. But most of the time transports seem to be the target of choice. I had 1 battle where six of my subs attacked 1 carrier fleet 2 light fleets and 7 transports (off Portugal) . Not one sub even took a shot at the carrier but they damaged a light and sank two transports. The rules say that HEAVY and LIGHTS are priority (i guess this refelcts the attemt to screen other ships), but transports screening a carrier?

[Joel Billings]

Actually, I think the heavy and light's being a priority is only for surface combat. Sub combat is completely random as to which targets are picked from all available enemy ships.

[Graymane]

CAG seems random as well. Nothing like catching the entire Jap fleet with 8 CAG and watching over 50% of them sink transports.