 After the poor performance of galleys in Russo – Swedish war of 1741 – 43 and the <unk> War ( 1757 – 62 ) , development of replacements became <unk> . During the <unk> War , trials had been made with " gun prams " ( <unk> ) , heavily armed , oar @-@ driven , flat @-@ bottomed barges with a shallow draft that carried guns in broadside arrangements . The prams carried more guns than the galleys , but proved far too slow to be effective . Augustin Ehrensvärd argued for new archipelago vessels that combined firepower , maneuverability , <unk> , and decent crew accommodations . He began a successful collaboration with <unk> Fredrik Henrik Chapman ( <unk> " <unk> Chapman " in 1772 ) , and together they developed five new vessels : a gunboat with a 12 @-@ pounder gun and a schooner rigging , as well as four types of " archipelago frigates " ( <unk> ) : the smaller <unk> and <unk> , and the larger turuma and hemmema . All four types have been called <unk> ( archipelago frigates ) in Swedish and English historical literature , though some authors have called the <unk> and <unk> " archipelago <unk> " . Chapman specifically designed the archipelago frigates for service off the south coast of Finland and named them after the Finnish provinces of <unk> , <unk> ( <unk> ) , <unk> ( <unk> ) , and Hämeenmaa ( <unk> ) . 
