The ministry of transport said VND 32 trillion ($1.53bn) will be cut, with the new investment figure set at VND 68 trillion up to 2020.
Deputy minister Nguyen Hong Truong said Vietnam's shipping sector had suffered in the global economic crisis.
The figures have been agreed with state-owned Vinalines.
Vietnam wants to raise its fleet to 95 ships, including 25 boxships and 20 tankers.
Vinalines
