Netherlands-based Jan De Nul Group has placed orders for one 6,000-cubic-metre and one 18,000-cubic-metre trailing suction hopper dredger (TSHD).
Newbuilding Department Director Robby de Backer said the diesel-electric vessels will be "best in class" for efficiency and emissions.
Accommodating 32 people, the 166.1-metre by 36-metre 18,000-cubic-metre vessel is equipped with a single suction pipe and a submerged dredge pump for dredging depths of up to 86 metres.
The hopper is subdivided in two parts, enabling sailing on even keel, at all loading conditions.
Two double-walled shore-discharging pumps with a total power of 14,000kW are installed.
Powered by two 7,500kW motors and total installed diesel power of 22,540kW, the vessel will reach speeds of up to 15.5 knots.
Cosco (Dalian) Shipyard will build the vessel in its shipyard in China. Its delivery is scheduled for 2020.
Keppel Singmarine will build two 6,000-cubic-metre TSHDs in Singapore.
Measuring 111.7 metres by 24.6 metres, they will be powered by two 2,150kW engines and 7,700kW of diesel power for dredging depths of up to 35 metres.
Accommodating 16 people, they will reach speeds of 12.5 knots.