Research Vessel San Carlos

The San Carlos was DWR’s first large environmental research vessel and operated from 1976 to 2016. It was custom built by the Campbell Yacht Company to perform scientific research and monitoring in the San Francisco Bay and Sacramento-San Joaquin Delta.


The San Carlos operated monthly within Delta waterways to conduct mandated monitoring of water quality, phytoplankton, zooplankton, benthic macro-invertebrate, and other special studies to ensure standards were maintained.

Equipment for monitoring has changed dramatically over the years. Before computers were prevalent, outputs from instruments were charted as electrical responses on long strips of paper. Eventually, the vessel was outfitted with more sophisticated equipment , such as the Turner 10AU and SEA-BIRD CTD 911 instruments, a flow-through system, and a computer collecting geographically referenced in-situ water quality data, including water temperature, dissolved oxygen concentration, specific conductance, turbidity, and relative chlorophyll a in vivo fluorescence.

As one of the oldest research vessels in the Delta, the San Carlos traveled thousands of nautical miles for research purposes. Over the course of its 40-year lifespan, the San Carlos was retrofitted with many upgrades and underwent major refurbishments, including replacement of the diesel engines in 1992. A major retrofit in 2004 repaired, replaced, and upgraded all above-deck structures, including the wheelhouse and the analytical laboratory, as well as substantial upgrades to the vessel's radar, electronics, and deck machinery.

Despite upgrades and regular maintenance, the San Carlos required replacement. The San Carlos was replaced by the Sentinel in December 2016.

For more information about the San Carlos and the work conducted on board, watch The Voyage of the San Carlos.


The San Carlos has the following features:

  • 56 feet long
  • 18 foot beam
  • 4.5 foot draft
  • 48 tons weight
  • Twin V8 Detroit diesel model 92 engines
  • 20 KW Marine Northern Lights Model 0964 generator
  • 11.5 knots top speed
  • More than 140 square feet of working space on the aft deck with a complete complement of working gear
  • 2 KOLSTRAND marine winches and davits to help deploy and retrieve sampling equipment including plankton nets and sleds being towed by the research vessel
  • A FASSI articulating crane to deploy equipment over the side of the vessel, including a SEA-BIRD CTD 911+ instrument collecting vertical profiling data and a PONAR dredge collecting benthic samples
  • More than 200 square feet as laboratory space for separate on-board wet and dry laboratories, complete with fresh and salt water plumbing, water quality filtering and titration stations, sample refrigerator and freezer, desk space, scientific instrumentation, and computers
  • Galley, bunkhouse, and head allowing scientists to comfortably conduct sampling during these extended studies at remote locations throughout the Delta
  • Onsite lab and base station for crews working on overnight and multiday sampling