Families and friends of loved ones who died in the tragedy in Belgium will gather at St Mary the Virgin Church in Dover - the place of the main memorial to the victims and also where some of their funerals were conducted.
Rt Rev James Jones, former Bishop of Liverpool, will lead prayers at the service.
On March 9 1987 the Herald of Free Enterprise ferry (above, in 1984) turned on its side in Zeebrugge. The incident became the worst maritime disaster outside of wartime in British history.
An inquiry found the ship left port with its bow doors still open, which flooded the car deck below. The person who should've closed it was asleep and an inquest jury found that all the people who died were unlawfully killed.
A manslaughter trial started but no one was convicted in relation to the 193 deaths. Further safety measures for ferry operators have come in since.
Various people were honoured for their bravery in rescuing people during the Zeebrugge disaster. They include Andrew Parker, who saved more than twenty passengers by allowing them to walk over his own body in order to get to safety - an act which has seen him called "the human bridge".
Retired Sailors' Society port chaplain Bill McCrea, who conducted the funerals of some victims, said: "One woman, whose husband I buried, had to wait six weeks before they found his body. I gave her all the support I could during that time.
"Who can train you for that? Not even theological training. You depend upon the grace of God. The families were a great support to me. I was there for them but they reciprocated that and as a result I got to know them really well."
"No one wants to be involved in this sort of tragedy and it was a big strain on me at the time, but supporting those I did is a great honour."
