The head of naval surface forces fears the sea service is teetering dangerously close to an operational cliff where ships simply won’t be available to do what they need to do.Vice Adm. Tom Copeman told the Surface Navy Association Symposium on Tuesday that sailors are being pushed to keep their ships up to snuff without being given enough time, spare parts or training to do proper maintenance. The Navy, he said, has been pushing personnel harder and harder, to do more with less, for years. Copeman pointed to rampant cross-decking, where sailors are snatched from docked ships and put on board deploying ones, often hindering maintenance on the docked vessel. He also said sailors are likely as not to be unable to find the spare parts they need on board their ship when something malfunctions or breaks. Eventually, he said, a day will come when a ship that needs to deploy won’t be able to. “It’s getting harder and harder, I think, for us to look troops in the eye and say, ‘Hey, just do it and meet the standard,’” Copeman said. “Some ships can do it. Some ships can’t.” Copeman said that the surface navy’s depot maintenance budget is practically at rock bottom right now for the size of the Fleet. If the budget gets any lower, he warned that the Navy risks creating a “hollow” Fleet.