Two Steam Packet sailings have been rescheduled next week.
On it website, the company says tidal conditions in Heysham mean two crossings will be affected.
The first, the Heysham to Douglas trip at 3am on Tuesday, will now leave at 3.30am.
Wednesday's 1.30am Heysham to Douglas sailing will now leave 40 minutes earlier at 12.50am.
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