St Peter Port Harbor will "close for business vessel developments" from 11:00 to 12:00 BST on Monday, harbor specialists have reported.
Condor Ships, which works the help, said "minor modifications" had been made.
The assistance from Poole to Guernsey has been postponed from 11:25 BST to 12:25.
It added: "Travelers are being educated regarding the change by our contact place."
The Ukraine-Russian conflict seemed to take a turn almost seven months after Russia attacked its neighbor
Ukrainian powers participated in a forceful counteroffensive, pushing back Russian soldiers and recapturing many square miles of domain.