I'm quite certain this is COLON X, originally the U.S. Navy tug TOPENBEE (YT/YTB/YTM 373). She became Crowley's tug ENVOY (ON 516578) and was used in Los Angeles harbor, with topside modifications identical to the vessel in this photo. She was sold in 1995 and registered under Belize flag as COLON V (IMO 8842428), but recent sources show her renamed COLON X in 2008. She is not a typical Navy 100-foot YT, but rather a 102-foot design developed jointly between Gulfport Shipbuilding and General Electric to market diesel-electric drive in tugs. Many of these were delivered to the Navy in WWII as YT's. Crowley purchased several of them surplus, but I believe this is the only one given this kind of stack.

I found some panoramio pictures of it on Google Earth and some others while searching about Isla Perico but no name. Still a mystery to me.