The Ministry of Defence has sent a plane to help search for four British sailors missing in the Atlantic.
The C-130 Hercules aircraft set off on Wednesday morning and is expected to reach the search area in the afternoon.
The 40ft Cheeki Rafiki was sailing back to the UK from an Antigua regatta when it started taking on water on Thursday.
Defence Secretary Philip Hammond said he hoped the yachtsmen would be found “as soon as possible”.
The US Coast Guard has resumed the search, which was called off on Sunday, following an official request from the UK government. The coastguard said it had searched a total of 2,878 sq miles so far.
But it warned it was battling against six-foot seas with wind speeds of less than 18.5km per hour.
The MoD confirmed the military aircraft was deployed from RAF Brize Norton in Oxfordshire at 05:00 BST. It flew to Lajes in Portugal to refuel, before heading to the search area over the Atlantic.
The plane is expected to join the international search effort at around 14:00 BST.
“The RAF's contribution to the search operation for the four missing British sailors will provide additional capability and resilience to the resumed search led by US and Canadian forces,” the defence secretary said.
“We all hope that the extensive resources being provided by our allies and the further support from the UK can help locate the missing yachtsmen as soon as possible.”
The four missing crew members are Paul Goslin, 56, from West Camel, Somerset; Andrew Bridge, 22, from Farnham, Surrey, the yacht's skipper; Steve Warren, 52, also from Somerset; and 23-year-old James Male, from Southampton.
Three planes and six ships have already been deployed to search the area where the sailors are thought to have disappeared – approximately 1,000 miles east of Cape Cod, Massachusetts.
Admiral Richard G Gurnon, president of the Massachusetts Maritime Academy, told the BBC the search from the planes and boats was an “extremely difficult task”.
“The weather is nasty, rarely is it calm and flat,” he said.
“And when you have four or five people staring out windows for four hours at a time looking for what is about the size of basketballs in the ocean, it's extremely difficult. It's tiring, so this is not an easy task.”
Adm Gurnon defended the coastguard's original decision to call off the operation, describing the organisation as “an extremely small outfit” faced with huge costs.
They thanked the UK, Canadian and US authorities and urged people to continue signing an online petition, which has attracted more than 200,000 signatures, to keep the search going.
The Cheeki Rafiki began taking on water 620 miles (1,000km) east of Cape Cod in Massachusetts and diverted to the Azores on Thursday. Contact was lost with the crew on Friday.