San Francisco Bar Pilots CARB-Compliant Station Boat Design

  • Client:
    San Francisco Bar Pilots
  • Key Collaborator:
    Noise Control Engineering
  • Project Type:
    Vessel Design & Modification, Tugs & Workboats
  • Service Categories:
    Naval Architecture
    Marine Engineering
    Acoustical Engineering
  • Vessel Overview:
    110-foot (33.5-meter) hybrid-electric station boat
  • Challenge:
    Design a hybrid-electric station boat that complies with CARB regulations.


San Francisco Bar Pilots are on call around the clock to help vessels navigate the busy waters of San Francisco Bay. A long-standing client, the bar pilots engaged Glosten to provide a feasibility study and contract design for three station boats that would meet the standards of the California Air Resources Board’s (CARB) new Commercial Harbor Craft (CHC) regulations. Unlike traditional pilot boats, which are specifically designed for pulling alongside ships and tend to be more compact as a result, station boats must be able to accommodate pilots standing by for duty and achieve the speeds necessary to perform the role of a pilot boat should the need arise. This added another dimension to the challenge of harmonizing CARB-compliant equipment, low noise and smooth vessel motions for pilot comfort, and a propulsion system that has enough horsepower for fast transit.

Vertical _3400_Version_Marine Log_Feb 2024


Glosten produced a design that features a hybrid propulsion system supplemented with batteries—an arrangement that reduces noise and allows the station boats to produce zero local air emissions while running on battery power. Traditional twin propulsion engines enable the boats to transit to station and keep up with larger ships when transferring pilots. A pair of smaller generator sets and a PTO/PTI hybrid arrangement support loitering while the main propulsion engines are off and provide a mechanism for charging the boats’ batteries at sea.

The new station boats will be six feet longer than the bar pilots’ current station boats to accommodate the battery banks, Tier 4 propulsion engines with SCRs, and diesel particulate filters which will make the vessels CARB compliant. The decision to make the station boats battery hybrid takes the design a step beyond California’s emissions requirements, making the vessels more adaptable to future regulations and upholding San Francisco Bar Pilots’ commitment to environmental stewardship.