A revamped coastguard service in Lincolnshire will be hampered by a "lack of local knowledge", say critics.
Under the proposals, 10 stations will close - including Great Yarmouth, which co-ordinates rescues along the coasts of Lincolnshire, Norfolk and Suffolk.
The government modernisation plans mean 24-hour cover will be provided from Aberdeen or Southampton.
But the Public and Commercial Services Union (PCS) said a reliance on databases would affect response times.
The comments come ahead of a public meeting on plans for the Great Yarmouth station, to be held at the town hall on Wednesday.
The government wants to cut the number of UK coastguard stations from 18 to eight, with the only 24-hour centres planned for Aberdeen, Dover and the Southampton/Portsmouth area.
Five sub-centres will be open during daylight hours in Swansea, Falmouth in Cornwall, Humber, either Belfast or Liverpool, and either Stornoway or Shetland.
Sir Alan Massey, chief executive of the Maritime and Coastguard Agency, said: "There are lots ways in which you can get local knowledge and we intend to exploit them a lot more smartly than we have done in the past.
"For a start the local knowledge currently in the minds of the coastguards who work for us - a lot of that's going to be retained anyway with those people who come to work with us in the new structure.
"The second point is that we need to capture and test and store and share local information in a way that's not been done up to now using geographic information systems, databases, all that sort of thing."
Paul Chapman, a Humber coastguard watch officer and PCS union member, said: "Lincolnshire will be totally without its own coastguard service.
"The coastguard will be provided from Southampton which is 250, 300 miles away so you can imagine there will be no local knowledge apart from what's on databases and the technology that Sir Alan talks about, but won't explain, and so there's going to be a significant delay in any response."
More than 30 people work at the Great Yarmouth centre.