With Callum McBrierty in for the sick Constantine Louloudis, GB progressed to Sunday's final after beating world silver medallists Australia.
Olympic, world and European champions Helen Glover and Heather Stanning reached the pair semi-finals with ease.
There were also wins for Britain's men's quadruple sculls, the lightweight men's pair and the open men's pair.
Including the men's and women's eights, who safely negotiated their heats, Britain has five crews in Sunday's finals in Switzerland.
London Olympic bronze medallist Alan Campbell also won his single sculls heat and then his quarter-final in balmy temperatures on the Rotsee lake to progress to the semis on Saturday.
The GB team topped the medal table at the European Championships in windy conditions earlier in May but with international crews joining this event - held on what is known as the 'Lake of the Gods' - the regatta is a step up in class.
With the Olympic team being named on 9 June, some unresolved issues still surround the women's eight.
Despite winning the European title in Brandenburg, one or two of the crew could be looking over their shoulders after team performance director Sir David Tanner said Olympic champion Katherine Grainger and Vicky Thornley could take their places.
Grainger and Thornley have been rested for this weekend following a poor performance in the women's double sculls in Germany.
Elsewhere, the lightweight men's four of Chris Bartley, Mark Aldred, Jono Clegg and Peter Chambers reached Sunday's final.
And Richard Chambers returned from injury to partner Will Fletcher as they reached Saturday's semis in the lightweight men's double sculls.
The second women's pair of Lou Reeve and Vicki Meyer-Laker, plus the lightweight women's double of Brianna Stubbs and Ellie Piggott both progressed to Saturday's semis via a repechage.
The new-look men's four were one of six British crews to win their heat on day one of the World Rowing Cup in Lucerne.