Kiwirail says it may cancel further ferry sailings on Saturday if the weather deteriorates further.
High winds drove the largest ferry, the Kaitaki into Picton wharf early on Friday afternoon, damaging its berthing equipment and preventing it from disembarking passengers safely which forced its return to Wellington.
Interislander general manager Thomas Davies says the weather is forecast to deteriorate and not improve until later on Saturday.
Mr Davies says the conditions in Cook Strait are getting rougher and swells are near the maximum height of six metres at which point Kiwirail will have to cancel all sailings.
At 6pm on Friday the wave height was about half a metre off that maximum height.
Mr Davies says Arahura is still sailing, but the Aratere has problems with its radars and mooring equipment, which means it cannot sail in heavy seas, and will remain in Wellington until weather conditions improve.
Kiwirail will refund passenger fares and offer them a free sailing back to Picton.
Mr Davies says technicians will examine the damage to the Kaitaki on Friday night and are expected to have repairs complete by Saturday morning.
Meanwhile many of the passengers travelling on the Kaitaki were to run a half-marathon near Blenheim on Saturday, but are unlikely to make it on time now.
Mr Davies, says Kiwirail will refund passenger fares and offer them a free sailing back to Picton but they may not get there in time for the event, which starts at 9am.