You may also be looking for the patrol corvette class of ship.
A patrol ship is a type of small warship in service with the UNSC Navy and some civilian organizations. As their name indicates, they are designed primarily for patrol duties as opposed to engaging in open space warfare. They are usually smaller than a corvette, sometimes no larger than a Pelican dropship. They are usually equipped with a small four-man shuttlecraft.
Ships of the line
List of appearances