The group planning to sink the old navy warship Wellington says it is too late and too expensive to keep it as a ship museum.

The decommissioned Leander class frigate is tied up at a wharf next to Te Papa in Wellington and is being prepared to be sunk at Island Bay as a reef and dive attraction in November.

Marco Zeeman from the Sink F69 Charitable Trust group said there had been several suggestions that the 3100-tonne ship should be turned into a museum.

"It is far too late now for that to be considered as the time for that to be a viable option was about 10 years ago," he said.

He said the ship had no anti-foul on the hull after it was stripped of all marine growth and anti-foul in dry dock at the Devonport naval base in Auckland before being towed to Wellington to be sunk.

"The cost of restoring the anti-foul on a very tired hull exceeds $500,000 and would require a trip back to Auckland," he said.

He said many of the fittings and furniture had been removed for sister ship Canterbury, which is also decommissioned and being prepared to be sold, in the past five years.

"The ship is certainly no longer a museum piece. All resources on the ship as far as power, ventilation systems, water, etc are dead."

He said the possibility of Canterbury being used as a museum ship was also investigated in the late 1990s and found to be unfeasible on financial grounds.

"It is not by accident the majority of maritime museums do not have ships as part of their exhibitions," Mr Zeeman said

He said many museum ships around the world were facing financial difficulty and relied on funding from governments and local authorities.

The destroyer Vampire at the Australian National Maritime Museum needed $1 million a year from the Australian government, he said.

The Wellington would be moored at Te Papa for visits and functions until November.

The Leander class frigate served 18 years in the New Zealand Navy after being launched by the Royal Navy as HMS Bacchante in 1969.