At the 1988 Summer Olympics in Busan, South Korea, he finished in 2nd place in the Soling class along with his partners William Baylis and Robert Billingham.

He was also designated skipper for Ericsson’s in the next Race (2008/2009) but resigned from his position in August 2007 for family reasons He sailed with America3 at the 1992 America's Cup.

The next America’s cup match took place between the defender, the Swiss team Alinghi, and BMW Oracle, in Valencia (Spain) in February 2010.

With Kostecki as tactician, the American team won both races against the defender and thus brought back the oldest trophy in sports history to the United States after 15 years.

Kostecki became very popular in Europe as skipper and helmsman of the German yachts all called "Pinta" owned by the Illibruck family.