NT men rescued from overturned boat

Four men have had a lucky escape after clinging to their overturned boat in Darwin Harbour for three hours before being rescued.

The boat overturned about 5.30am on Sunday after it took on water during a thunderstorm, police say.

The men put on life jackets and dropped anchor before the boat overturned more than 5km off Darwin's East Point.

The group set off distress flares but the wind and poor visibility meant they weren't seen, forcing them to wait three hours until they were spotted by the crew of a passing fishing vessel.

"The men were very lucky in the circumstances. It was a very dangerous situation, but the men realised it early and prepared by putting their life jackets on before they hit the water," said Sergeant Andrew Hocking of Northern Territory Water Police.

"They were all amazed at how quickly it all happened and were very grateful they were carrying all of their safety equipment."

The same storm caused a 15-metre yacht to break moorings and drift towards Stokes Hill Wharf, but the skipper dropped anchor 100m from the wharf.

A 16m fishing trawler dragged its anchor for several hundred metres off Darwin.

Meanwhile, five people including a seven-year-old boy had a lucky escape after their motor boat broke down on a turtle fishing expedition off the Tiwi Islands coast about noon on Saturday, police say.

The crew, which included four men, set off without life jackets and appropriate safety equipment, and with a few snacks and a small amount of water, about 9am.

The group managed to beach the vessel near a creek 25km from home, while loved ones raised the alarm.

A member of the party walked through bush to get mobile reception and made contact with authorities about 7.30pm.

The five were rescued by a police vessel.

No one was hurt but they had signs of dehydration and exposure.