(CNN) -- With difficult weather conditions conspiring against rescue efforts and frustrated, angry relatives accosting officials at Jindo port, chances of finding survivors from the Sewol ferry that unexpectedly sank Wednesday are decreasing with each passing hour.
On Friday, the South Korean Coast Guard said workers continued to pump air into the hull of the submerged ship, but could not arrest its descent. This provoked theories any remaining air pockets in the vessel had disappeared.
Rescuers said there is still a slim hope of finding survivors even though the bow finally slipped beneath the water surface Friday morning.
Rescuers are turning to heavy engineering solutions to aid the hundreds of divers attempting to access the wreck and the potential hundreds of passengers trapped within.
Shift of focus
The arrival of three huge seaborne cranes at the site Friday added to relatives' fears the focus of the mission would soon shift from search and rescue to salvage.
"What those cranes signify ... is that this is no longer a search for survivors. It is a long term process of lifting the hull, and those cranes are going to turn this from a search and rescue mission to a recovery," CNN correspondent Kyung Lah reported from Jindo.
The cranes will be used to help lift at least part of the ferry out of the water.
Salvage crews maneuvered the three 3,600 ton floating cranes into position. A further crane due to expected to arrive later Friday.
Difficult, slow operation
Efforts to raise the ship mechanically are likely to be fraught with difficulty and the operation itself a slow process.
If it is winched up incorrectly, it may tilt or sink deeper into the seabed.
"It will be difficult for the cranes to immediately be employed into the raising process so we're conjecturing it will take months until this process is over," a member of the Coast Guard told Asia Economy, a local South Korean publication.
"In order to search for survivors we will instead focus on just raising part of the ship."
A different coast guard official assured families nothing would be done to jeopardize the safety of any possible survivors who may still be in the stricken ferry.
"Let me be clear: There won't be any salvaging work done against the will of the bereaved families," Kim Soo-hyun, a regional coast guard commander, told journalists at a briefing broadcast by CNN affiliate YTN early Friday.