The Navy has warned in a report to Congress that it won’t be able to afford the cost of replacing ships slated to retire in the years ahead and the next decade based on current budgeting, a dilemma further complicated by plans to build the next generation of ballistic missile submarines. In its annual congressionally mandated 30-year shipbuilding plan dated July 1, the Navy said its fleet of ships built in the 1980s and 1990s comprise most of the current…