The Total Naval War rule is part of the Total War concept.
In Early 1943 World War II is defined as a Total War - and mass production of specific land and air units benefits the major powers (see pg. 50 in the G40 HRE rulebook).
The Total Naval War is designed with the same game mechanisms as Total War, but concerns only specific Naval units and specific Nations.
We expect to release the Total Naval War rules in Late 2025, when play testing has ended.