The co-ordination centre at a Norfolk coastguard station is set to shut under changes announced by the government.
The station at Great Yarmouth employs 36 people and covers North Sea emergencies along the coasts of Lincolnshire, Norfolk and Suffolk.
A 14-week consultation period will now begin into the proposals.
The RNLI, whose lifeboats work closely with the coastguard on offshore emergencies, said local knowledge would remain.
The area covered has many offshore installations and hazards, including gas production platforms, wind farms and sand banks.
In daylight hours the coastguard service will be provided in future from a station on Humberside and 24-hour cover from Aberdeen or Southampton, under the government proposals.
Shipping Minister Mike Penning said the changes addressed weaknesses with a system that was 40 years old and needed updating.
"There are also increasing numbers of people using our beaches, coastlines and seas for leisure activities," he said.
The MP for Great Yarmouth Brandon Lewis said the coastguard service needed modernising.
He insisted that it was only the back office operation that was affected at Great Yarmouth and there would be no compulsory redundancies.
"We are moving to a modern far stronger response system like those used by the police and fire service.
"The same people, based locally, will be doing the rescues," he said.
But he admitted he had not yet spoken to the RNLI and independent lifeboats supporting the coastguard.
The RNLI said it worked "extremely closely" with the coastguard and appreciated in the current economic climate very hard decisions had to be made.
"We are looking closely at the way civil maritime search and rescue co-ordination will now operate in the UK.
"Our lifeboat assets are, in the overwhelming majority of cases, requested to launch by the coastguard once the emergency call has come into a centre.
"We have been reassured the standard of search and rescue co-ordination will not reduce.
"A possible criticism of the closure is that it will affect the levels of local knowledge during any maritime search and rescue situation.
"However the RNLI's volunteers always give their very best to any rescue operation."