The Motor Anti-Submarine Boat 27, the only one of its kind in a seaworthy condition, has been restored in time for D-Day.
It will join fellow coastal defence veteran vessels in its first cross-channel journey to Normandy since the war to mark the commemorations.
'D-Day Revisited' started the project to save her in 2016, moving it by road to Hawarden Airfield, just outside of Chester.
She is currently in the marina on the River Hamble in Hampshire.
John Phipps, the man behind the restoration, said:
"A lot of it has been estimation and calculation because all the drawings haven't been available.
"It looks as though it is sitting pretty good."
During the Second World War, the boat and many others like her were built to defend coastal waters from the threat of Germany U-boats.
When that threat receded, they took on other roles.
MASB 27 was used to drop agents in German-occupied Europe and rescued RAF personnel smuggled to the coast by the French resistance.
Felicity Jaffe's father saved the boat in 1945 and the family used her as a houseboat for 30 years before Mr Phipps and his team restored her.
"I suppose the boat was one of my most important things in my life, so it was a bit emotional really," she said whilst watching the boat get lowered into the water.
Soon the sea trials will start and on 5 June Motor Anti-Submarine Boat 27 will have D-Day veterans on board on the river at Pegasus Bridge in France.