Hyundai Engineering and Construction announced a first-quarter profit of $35.2 million, four times the year-earlier figure.
Samsung Heavy Industries reported net income last year of $93 million, nearly twice the year-earlier figure.
The year-earlier figures are presented as if the merger had been in place in the second quarter of 1989.
The company began production in 1988 and year-earlier figures were not provided.
That offer produced an 86 percent increase in sales in four months over year-earlier figures.
It was the fourth consecutive quarter of declining profits, versus year-earlier figures.
Sales of $93.6 million, a second-quarter record, rose 21 percent from the year-earlier figure of $77.1 million.
Revenues for the nine months totaled $2.7 billion, down 2.4 percent from the year-earlier figure.
The year-earlier figure included $7 million of gains from the sale of securities.
The company said the year-earlier figures represent results of operations for four months only as commercial production did not begin until March 1, 1989.