The Coastal Motor Boat Number 4 (CMB4) torpedoed a Bolshevik cruiser in action following the Russian Revolution.
A team of volunteers took six years to build the exact replica from the original plans and have held successful sea trials off Portsmouth.
Volunteer team lead David Griffiths, a retired shipwright, said the project had been "hard work all the way".
The original 40ft vessel - now part of the Imperial War Museum's collection - could reach speeds of up to 40 knots and was used to attack much larger ships during World War One.
RSPCA & J. B Gill
Amazing day working to produce this with the RSPCA and J B Gill