Two bronze propellers weighing 1.5 tonnes each have been stolen from a boat yard in Portsmouth.
The propellers could be worth £16,000 as scrap metal and were taken from Trafalgar Wharf on Tuesday.
Hampshire Police said three men forced a security barrier up and entered the yard in a flatbed lorry with a crane.
Pc Hannah Vardy said: "With scrap metal prices so high, we believe this theft to have been committed by organised offenders."
The three-bladed propellers are approximately 6ft in diameter.
Police are appealing for witnesses.
