Richard and Peter Chambers clinched a bronze medal in Sunday's lightweight double sculls final in Lucerne.
The Coleraine brothers were second going into the last 500m but slipped to third in a race won by France.
There was disappointment for fellow Coleraine rower Alan Campbell after he finished sixth and last in the single sculls final on Lake Rotsee.
Campbell led at the 500m mark and was second at halfway but faded and was 14 seconds behind winner Ondrej Synek.
Olympic silver medallist Synek beat Campbell into second place in Saturday's semi-finals.
The Czech Republic rower won by two seconds from Germany's Marcel Hacker with Cuban Fournier Hernandez in third.
The Chambers pair finished over two seconds adrift of the French crew, with Italy taking silver.
They won their heat but had to settle for second behind the Italians in their semi-final on Saturday.
Lucerne is the third and final World Cup regatta of the season and is the last chance to lay down a marker before the World Championships in Korea.