The most recent port offer included a 10 percent rise in hourly rates, performance bonuses of up to 20 percent, and the retention of existing benefits and entitlements in return for a new roster system it says will provide increased operational flexibility.
The MUNZ website says that of the issues being disputed, the roster is the main concern, with a belief that the flexible roster will result in less hours and subsequently less pay.
"The union position is clear. It does not want the 10 percent - it wants secure ordered and transparent rosters".
Union workers are preparing for a 48 hour strike beginning at 11pm tonight - the fifth staged since November.
Three ships have been affected by the strikes, with one bypassing, one being serviced at the ports' multi-cargo wharf, and the third delayed by approximately eight hours.