Fourth rates occupy an awkward position in the system: they were the smallest two-deck ships, useful but increasingly less suited to the main European battle line. The category's apparent growth may include converted East Indiamen and razeed frigates alongside purpose-built fourth rates. They were especially useful on overseas stations such as the Caribbean and East Indies, where a heavier ship than a fifth-rate frigate was wanted without the expense of sending a third rate. HMS Africa shows how a nominal 64-gun third rate could be treated in practice much like a fourth rate. By the Trafalgar period, the useful line-of-battle standard was moving toward 74 guns and above.
Notable Point · 25:50-28:35
Fourth rates and overseas stations
The smallest two-deck ships were often useful abroad, where a fourth rate could provide more weight than a frigate without the cost of detaching a third rate.