The HM coastal patrol vessel Eagle will scour the waters as migrants look to sneak into Britain.
The 20 metre-long craft , which can travel in excess of 30 knots [35mph] and has a crew of up to six, was put into service last week.
Border Force also has two cutters, HMC Seeker and HMC Valiant, in anticipation of a week of raids.
Retired Coastguard officer Andy Roberts said: “What this will do is put a warning out to anyone.
“We already have cutters such as Vigilant and the Valiant but now we have a craft that will outrun anything out there.
“It is getting colder and they [migrants] haven’t got much time.
“In summer you have a chance, but in winter they’ll die of cold before they make it across the Channel.
“They’ll need to get people on the boats. I’m surprised they haven’t got a big fishing trawler and filling it with people.
“They can get over and land on the beach; that’s the goal. Then they’re in the system.”
Since March, immigration officials have intercepted nine migrant boats between Kent and Sussex.
The Home Office said: “The UK has one of the most secure borders in the world – we use a combination of cutters, teams on shore and aerial surveillance to intercept those attempting to enter the UK illegally and target the organised gangs that profit from people smuggling.
“In addition, we have begun to introduce a number of additional coastal patrol vessels to complement this work.”