Who pirated a 27-foot Boston Whaler from a residential dock last month in East Quogue?

That’s what investigators want to know — and now they’re asking the public’s help finding the waterborne thief or thieves.

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Suffolk County and Southampton Town police said the 2013 Dauntless with a 9-foot beam is powered by two Mercury 200-hp. CXL L4 Verado four-stroke outboard engines. The boat was taken from the residential dock along Sunset Avenue sometime between Aug. 13 and 17. The crime scene is located along Phillips Creek and Shinnecock Bay. The hull identification number of the Whaler is BWCE0730J213, police said.

The engine serial numbers are 1B979235-1B967612.

Police have released a photo of the same model Whaler stolen and are asking anyone with information about the theft to call Crime Stoppers at 800-220-8477.

All calls will remain confidential. Callers are eligible for a cash reward of up to $5,000 for information leading to an arrest.