A British yachtsman’s boat sank after it was attacked by orcas in the Strait of Gibraltar.

Robert Powell and two occupants of the Bonhomie William had to be rescued by Spanish coastguards when orcas buffeted the vessel at night.

The whales disabled the vessel’s steering and the boat started taking on water.

“Sadly these (orcas) were not playing. It was a well-orchestrated and organised attack to sink by boat,” Mr Powell, a London-based managing director, said in a social media post.

“We were all rescued and are safe now.”

He posted a film of his yacht disappearing under the waves in the sea off the coast of Tarifa and Barbate in southern Spain.

“A yacht sailboat called Bonhomie William which was two miles off Camarinal Cape between Tarifa and Barbate reported that after interaction with orcas, she needed to be towed as her steering system was inoperative,” the Spanish coastguard said in a statement.

“The skipper added that the three people on board were okay and the vessel was taking on water.

“Our Tarifa centre mobilised coastguard vessel Salvamar Enif. The sailboat then called again to report the orcas were still interacting and it was now taking on water. The crew were told help was on its way and to prepare to pump water.” 

The statement said Salvamar Enif had reported two flares in the area, followed by a parachute flare when it was close to the other vessel’s position. 

“On arrival, it reported the life raft had been thrown into the water and the yacht had lost its waterline. The Salvarmar Enif crew rescued the three people on board and reported they were all okay.”

Killer whales have launched a spate of attacks in recent years, ramming the rudders or sides of boats. Marine biologists believe that the whales may be attacking out of boredom.

A humpback whale also capsized a small fishing boat with two sailors on board off the coast of New Hampshire in the US on Tuesday.

Video footage captured the moment when the whale breached the waters and smashed its snout on the back of the vessel.

Greg Paquette and Ryland Kenny were tossed into the waters off the city of Portsmouth and escaped unhurt.

Experts said the whale appeared to be “lunge feeding” – a way of catching fish – when it hit the boat.