Peacetime roles for merchant shipgirls

What could merchant-cruiser and boarding-ship characters do in peacetime, and which type would suit it best?

Merchant-derived types could return to commercial work, while warship types could perform continuing peacetime naval duties.

The fictional question concerns armed merchant cruisers, armed boarding steamers and ocean boarding ships. Their real starting point is commercial shipping, so ordinary merchant work provides a suggested peacetime role. Adding guns for war does not remove that underlying function. Peacetime usefulness need not be restricted to one warship type, since naval duties continue.