It's believed the trailer went missing sometime between 5pm Tuesday and 6am Thursday at their Pilot House in Crookhaven Heads.

Marine Rescue Shoalhaven unit commander Bill Carter said because the trailer is missing, their capacity to save lives is reduced.

"Without that trailer, we're unable to refuel our smaller vessel," he said.

"I'm just cranky, we're always getting things stolen."

Thankfully, the larger vessel owned by Marine Rescue runs on diesel so can still be operated.

Mr Carter said at the time the trailer was stolen it had 400 litres of fuel left in it.

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The trailer itself was worth around $18,000.

"And the replacement cost is likely a bit higher as it was purpose-built for the job," he said.

It's not the first time Marine Rescue Shoalhaven has been the victim of theft, recently they had three flags stolen and the back of a boat damaged.

Marine Rescue urges anyone with information to contact Crime Stoppers on 1800 333 000.