Private companies, emergency services and the navy are sending ships and boats to Mallacoota carrying supplies for up to two weeks with the fire-ravaged coastal town still unreachable by road.

On Wednesday, Premier Daniel Andrews said helicopters had been used to facilitate a “shift change” at Mallacoota by flying in about 90 fresh firefighters and flying their weary colleagues out.

Esso's Far Saracen supply boat arrived off Mallacoota on Wednesday.

Esso sent one ship and two helicopters to Mallacoota by Wednesday morning, after being asked by state emergency services to provide support.

The fuel company was preparing a second boat to head to the small East Gippsland town in the next 48 hours, it said. Operating out of Longford, south of Sale, the boats and choppers usually supply Esso's gas rigs in Bass Strait.