Convoy escort

A convoy escort was a larger patrol ship classification used by human militaries such as the UNSC Navy, planetary defense forces, and some private military contractors.

Characteristics
An offshoot of frigates, convoy escorts are somewhat smaller, more economical craft that can be mass-produced during crises to protect slow-moving civilian craft. They generally occupy the size gap between frigates and corvettes, with an average length of 350 meters (1,150 ft) and a mass of ~750,000 metric tons. Though most are built to the same standards used in civilian vessels, even those that meet all military shipbuilding regulations are still generally more poorly armored than dedicated warships. Indeed, this has contributed to a general reputation of being fragile, barely more protected than the freighters they're guarding.

Convoy escorts are strictly built with a defensive role in mind: they must fight off any merchant raiders that they come in contact with, distracting them long enough to allow the convoy to scatter. Running enemy ships down is out of the question, and in any case can compromise the safety of the convoy. For this reason, convoy escorts are slow, nowhere near fast enough to keep up with even cruisers, which makes them a liability in fleet operations. It is also why most have a multi-layered sensor network that, while hardly advanced, is enough to detect most raiders and some outdated prowlers at extended distances. The advantage of going slow means that they do have a very long operational range and low upkeep, usually achieving this by using old hot fusion reactors even well into the Human-Covenant War.

Though they are designed to relieve frigates and destroyers, they are not intended to stand in for them. The need for low crew numbers has compromised their weapons, which ranged around missiles and plenty of point defense armaments. Even MACs tend to be small, being adapted from those used on corvettes. Still, while they are not able to defeat larger ships in a standing fight, they still pose a threat by taking out important systems and stores in a drawn-out fight - something that is still a risk for any unsupported raider operating far from home.