AMs debate plans to close coastguard stations in Wales
Concerns over plans to close two of Wales' three coastguard stations will be debated later by assembly members.
The UK's Department for Transport (DfT) wants to close Milford Haven and Holyhead stations, with only Mumbles staying open in daylight hours.
AMs have expressed fears about call-out times and risk to lives.
The DfT said frontline coastguards would be unaffected and it would mean a modernised coordination of rescues.
The UK government want to cut the stations from 18 to eight across the UK.
Of the remaining eight stations, three would operate round the clock - Aberdeen, Southampton/Portsmouth area and Dover.
The remaining five - Mumbles in Swansea, Falmouth in Cornwall, Humber in Yorkshire, either Belfast or Liverpool and either Stornoway or Shetland in Scotland - would only operate in daylight hours.
A public consultation on the issue ends on 24 March.
Mid and West AM Joyce Watson will be leading Wednesday's debate.
Mrs Watson, a Labour spokeswoman on rural affairs, said she called for the debate because she was concerned about the effect on response times if the closures went ahead.
"The concern for everybody is that these proposals will cause a delay in call-out times and lives will be lost as a result, especially because plans to sell-off search and rescue helicopters and reduce the services available from RAF stations like Chivenor will mean the rescue response along the Welsh coast could be even further compromised.
"The UK Government claims that response times will not be affected, but where is the proof? I wrote to the Secretary of State to request a copy of the impact assessment but all I received was the same unsubstantiated 'assurance'."
Mrs Watson said that First Minster Carwyn Jones confirmed that he would be writing to the UK transport minister about the proposed closures.
She added that in the last five years the Holyhead coastguards have responded to 4,286 incidents.
The rescue team in Milford had co-ordinated more than 3,624 emergency callouts and taken part in nearly 4,349 operations.
A DfT spokesperson said the service needed "modernisation".
"Our proposals to modernise the way coastguard rescues are coordinated have been risk-assessed at every stage of the process.
"These proposals are in response to a long-overdue need for modernisation, and the new, fully-integrated national network of coordination centres will actually increase resilience.
"The front-line volunteers who carry out the rescues are unaffected by these proposals, and will actually benefit from improved management and training."
Those involved in the sailing industry in Pembrokeshire said local knowledge was important in co-ordinating a rescue.
Louis Howe, Havenmaster at Neyland Yatch Haven, said the waterways around Milford Haven had some of the highest tidal ranges in Britain and it was vital that coastguards knew them well.
"When people leave this marina and go out into the estuary I think they are reassured that there is a coastguard station nearby if they need help and the staff have got the knowledge of the area that they are dealing with.
"if the nearest coastguard station is in Swansea the people manning that station are not going to have that knowledge of the Milford Haven waterway."
Blake Shaw, secretary of Tenby Sailing Club, said: "It's difficult to know the effect. On the surface I think there will be very big gaps between stations and local knowledge will suffer."