Boskalis revenue from its offshore energy business fell 27.5% to €966.7m last year, from more than €1.3bn in 2016.
The Dutch outfit blamed continuing poor conditions in the oil and gas sector and a "limited" contribution from offshore wind foundation installation compared with the previous year.
However, the decline in the foundation installation was partly offset by a stronger year for Boskalis' cable-laying business.
The company said by the end of 2017 it had secured cable laying contracts for the East Anglia 1, Borssele Beta and Hohe See projects, as well as an unexploded ordnance survey and identification deal for the Borssele offshore wind zone.
Its VBMS subsidiary is also the preferred cable-lay supplier for the Triton Knoll and Moray East offshore wind farms.
Earnings in the offshore energy business also fell last year to €221.1m from €374.7m in 2016.
Overall, Boskalis reported revenue down to less than €2.4bn last year, from almost €2.6bn in the previous year. Earnings also dropped to €436.6m from €660.5m, and net profit fell to €150.5m in 2017 from €276.4m.
Boskalis chief executive Peter Berdowski said the company does “not yet foresee a fundamental recovery” in its markets in the coming years.
“In the short term we do however expect opportunities for selective growth and a subsequent structural recovery for the period thereafter,” he said.