Four Steam Packet sailings are at risk through Friday into Saturday with poor weather set to hit the island.
Moderate to rough seas are expected tomorrow into Saturday morning.
As a result, the 8am sailing to Heysham on Friday morning and afternoon are at risk of disruption, with a final decision due by 6am on Thursday.
The later sailings, 7:15pm on Friday and 1:45am on Saturday are also at risk, with a decision due by 5pm.
The company said: “Passengers may amend their bookings free of charge through their online account, or alternatively you can contact our reservations team on 01624 661 661 or 08722 992 992.”