A 20-year-old man has been arrested while allegedly trying to carry a weapon and ammunition on to the Spirit of Tasmania passenger ship in Devonport on Tuesday night.
It is understood police were called to the port when the weapons, reported to be a replica firearm and knives, were discovered by security.
The man did not gain access to the vessel.
The man was later charged with possessing ammunition without a licence, possessing a firearm part, possessing a dangerous article and possessing an unregistered firearm, the ABC reported.
He was granted bail and will appear in a Devonport court on a later date.
"Nothing that was in his possession was capable of discharging the ammunition he had with him," Detective Inspector Robert Gunton told the ABC.
The Spirit of Tasmania carries up to 1000 passengers daily between Devonport and Port Melbourne.
The operator, TT-Line Company Pty Ltd, is owned by the Tasmanian government.
Inspector Gunton said police had increased their patrols of the ship following the raised national terrorism alert level, which was lifted to "high" on September 12.
