From CoD:
“I’m sure you know the RMN’s history,” Breakwater said, turning back to Winterfall. “From the four frigates that the Trust, had waiting when the colony ship arrived, it grew to nineteen by the time of the first skirmish with the Free Brotherhood, seventeen years later, then to a total of thirty-four warships over the next forty years.”
“And now here we sit with twenty-eight of the damn things,” Chillon growled. “All of them draining funds from the treasury like giant blood leeches.”
So, as of the Beginning of Call of Duty, the RMN had 28 ships:
9 Triumphant BCs
6 "unnamed class" DDs (an "old" class of RMN DDs - "Protector" was mentioned, do not know if current)
7 Pegasus Corvettes
2 named CAs
1 named CL
3 other ships (FG/CL/CA?)
1 BC was lost (Mars)
As of Call to Arms - the shipcount at the beginning of the book was 27.
19 ships were active - the other 8 were in refit.
Ship losses in First Manticore were:
1 CA (Sphinx)
2 DD (Phoenix and Gorgon)
2 Corvettes (Hercules and Gemini)
Volsung losses
2 BC
1 DD