* Appointment effective Sept. 1

* Current CFO to stay on as consultant (Adds details on Cauthen as consultant, background)

HOUSTON, May 21 (Reuters) - Transocean Ltd (RIG.N: Quote, Profile, Research) has named the head of its European and African unit, Ricardo Rosa, to be its new chief financial officer, the world's largest offshore drilling contractor said on Thursday.

Rosa, 52, succeeds Gregory Cauthen, 51, who said last month he planned to leave the company, which recently moved about a dozen senior executives to Switzerland from Houston as part of a reincorporation for tax purposes. Cauthen had also been due to move to Europe.

Rosa, whose appointment is effective Sept. 1, will be based in Geneva and report to Chief Executive Robert Long. Rosa had only taken up his current position in Paris last March, having run the Asia and Pacific unit before.

Cauthen will stay on as a consultant to work on projects related to tax, evaluation of proposed transactions and system design and enterprise resources planning, the company said. The one-year contract pays just under $44,600 per month. He also gets a lump-sum $1.2 million pension equalization payout.

Shares of Transocean ended 1.7 percent lower at $71.87 on the New York Stock Exchange, while the Philadelphia Stock Exchange oilfield service company index shed 4 percent. (Reporting by Anna Driver and Braden Reddall in San Francisco, editing by Gerald E. McCormick and Andre Grenon)