http://www.cbo.gov/ftpdocs/87xx/doc8771/10-31-Navy.pdf

Excerpts:

"With that traditional single-crewing concept, the Navy needs a force of six surface combatants to keep one onstation at all times in Central Command—or a rotation ratio of 6 to 1. For European Command or Pacific Command, the analogous ratio is 4.5 to 1. The goal of the Sea Swap experiments was to try to reduce those ratios by gaining more forward presence from a given group of ships."

"12. However, section 342(b) of the John Warner National Defense Authorization Act for Fiscal Year 2007 (P.L. 109-364; 120 Stat. 2154) prohibits the Navy from implementing any new crew rotation experiment or program on surface ships until October 1, 2009."