A text from: http://historicalfact.com/~ark/quad/frigates.html

The 'Chapman Frigates'

The ten ships of the Bellona class, laid down by the Swedish Navy as part of the radical re-armament programme instigated in 1782, are normally accepted as the first 'super-frigates'. Sweden had declined steadily since her military heyday under Gustavus Adolphus, and her navy in particular had suffered in the endemic wars with Denmark-Norway and the Russian Empire through the eighteenth century. Naval warfare in the shallows and narrows of the Baltic, among islands and inlets and in inshore waters where a wind could fall away suddenly and unexpectedly, was a rather specialised affair, in which vast gunboat flotillas operated alongside the opposing fleets, and Sweden, in economic straits, could not match the sheer scale of the forces deployed by her old enemy Russia.

These oar-driven gunboats mounted a few heavy, long-range guns in the bows (typically twenty-four pounders), and relied more on brute force than conventional sailing skill. They could be cheaply and quickly built and crewed by soldiers, and still posess superior manouvrability to sailing warships, especially in the awkward conditions of the Baltic. They posed a real danger to frigates, merchantmen and even small ships of the line, which could find themselves under devastating fire from even a modest force of gunboats and unable to strike back.

By the 1780s, the Swedish Navy was in a bad way. Their ships were old, small and few in number. The gunboat flotilla had been transferred to army control back in 1756, and in 1780, the blue-water navy suffered perhaps the ultimate indignity when Henrik af Trolle, the able commander of the flotilla, was placed in overall command of naval operations. In 1782, it was resolved to rebuild the navy, but with an impoverished exchequer and an overpowering enemy in Czarist Russia, it would be a remarkable man who could do so successfully. Fortunately, there was a remarkable man to hand, Fredrik Henrik af Chapman, perhaps the greatest naval architect of the eighteenth century.

Chapman was the son of a Yorkshire shipwright who had become the Superintendent of the Royal Dockyard in Gothenburg, and he followed his father's trade, but, far more than a master craftsman, he was the Enlightenment's great theoretician of naval architecture, being raised to the nobility and promoted to the rank of Vice-Admiral for his services. What he was asked to do in 1782 - to design and build an entire navy, from the line of battle to the smallest class of gunboat, as a single, unified and integrated force, and to do so on the tight budget which was all even an enthusiastic Sweden could afford - was within few men's capabilities, but he was up to the challenge.

The backbone of the Swedish fleet was to be formed by the ten Rattvisan-class sixty-gun ships. They were tough, economical little ships, an effective compromise between firepower and the demands of Baltic warfare. The gunboat flotilla was rationalised with several excellent standard designs, ranging from what were essentially open boats with guns in the bows to vessels like heavily armed naval sloops. But if the '60's and the gunboats bore witness to Chapman's ability, the Bellona-class frigates were, perhaps, his masterpiece.

As intermediaries between the battlefleets and the flotillas, frigates made perfect sense: their shallower draught enabled them to serve as major units in inshore waters where ships of the line could not go, and, unlike battleships, they could be rowed, a distinct advantage when navigating amongst islands and shoals, supporting gunboats against gunboats. They could serve as the flagships of flotilla forces, or even support the battlefleet in close action. The problem was that the twelve-pounders of the largest frigates employed until then in the Baltic would be seriously outranged by gunboats' long guns, and would be equally useless in ships expected to add their firepower to the line of battle.

Chapman's answer was to build frigates to carry twenty-four pounders, more than a match for the Russian gunboats, and strong enough to back up the line of battle. In peacetime, the ten Bellona- class frigates cruised with eighteen-pounders, but, just as the '60's were intended to upgrade from 24- and 18-pounders to 36- and 24-pounders in wartime, they could be speedily rearmed. One presumes that the 500 18-pounders left spare by rearming all these ships would then be mounted aboard new gunboats.

The Bellona and her sisters were among the largest frigates then built, but, being intended for the Baltic, they did not have to carry nearly the same amount of stores as their ocean-going French and English cousins, and so they had a shallow draught (less than ten feet) and fine lines. Some of them, if not all, could even be rowed. Unusually for frigates, their captains' cabins were set on the quarterdeck, beneath a small poop. This gave them something of the look of East Indiamen, but probably reflected practical considerations rather than Chapman's training in the Swedish East India Company's shipyards: it allowed an extra main-battery port a side, and, more importantly, enabled the aftermost guns to be worked through proper stern-ports - an important advantage if a frigate was caught in a calm by gunboats attacking from astern.

Chapman's frigates were typically innovative and well-designed ships, but it should be noted that the Swedes had considered building ships mounting 18- or 24-pounder batteries on a single gundeck as early as 1718, almost a generation before the French Royal Navy launched the first true 'frigates' in the 1740s. These large cruisers were never built, but, like the Chapman frigates, they were a response to the particular needs of the Baltic navies for a ship of force which could operate in restricted waters. Chapman is likely to have known about these proposals, and they make it clear that the Bellona class belong to a line of warship evolution at least partially independant from that which had led to the development of the frigate as the major cruiser in the world's navies.

But even if the Chapman frigates were a response to a particular set of circumstances, and in a way perhaps not really designed as frigates at all, they nevertheless impressed foreign officers who served temporarily in the Baltic navies, and the high commands of most European navys contrived to acquire a draught of one of them to study. The history of the Venus also demonstrates that, in spite of their shallow draught and lack of space for provisioning, they could operate outside the Baltic. Captured by the Russians in 1789, this ship saw service under Imperial colours in the North Sea and the Mediterranean, being eventually made over to the Neapolitan navy after Vice-Admiral Seniavin surrendered his squadron to the allies in 1808.

Their role as pocket battleships and flotilla flagships, notwithstanding, the Chapman frigates prefigured what was to come: quite apart from their primary advantages in gunboat operations and supporting ships of the line, their broadside would have been devastating in ship-to-ship combat against a smaller frigate. It may have been this realisation which prompted the French Royal Navy to lay down the Pomone.