Gato and Balao Class Submarines — Asbestos in WWII Diesel Submarines

The Gato class (SS-212 through SS-284) and Balao class (SS-285 through SS-425) fleet submarines were built in large numbers between 1941 and 1945 at Electric Boat (Groton, Connecticut), Portsmouth Naval Shipyard (Kittery, Maine), Mare Island Naval Shipyard (Vallejo, California), Manitowoc Shipbuilding, and other wartime builders. These vessels used Fairbanks Morse opposed-piston diesel engines or General Motors diesel engines in a diesel-electric propulsion arrangement — diesel engines running electric generators that powered the propulsion motors. Despite the absence of steam boilers, these diesel-electric submarines contained extensive asbestos in their engineering spaces, interior construction, and auxiliary systems.

Diesel Engineering and Asbestos Aboard WWII Submarines

Gato and Balao class submarines used Fairbanks Morse and General Motors diesel engines with asbestos-containing components in multiple maintenance-intensive applications:

• Diesel engine exhaust system gaskets on the Fairbanks Morse opposed-piston and GM diesel engines using asbestos spiral-wound and sheet gaskets in high-temperature exhaust manifold service
• Exhaust piping insulation on the diesel exhaust runs from engine room to muffler and hull penetration using asbestos block and sectional covering on high-temperature exhaust lines
• Electrical switchboard insulation in the main control room and maneuvering room using asbestos-containing insulating boards and cable insulation in high-current electrical systems
• Pipe insulation on hot water systems, refrigeration equipment piping, and battery ventilation systems using asbestos-containing covering in the enclosed submarine spaces
• Interior construction of crew’s berthing, torpedo rooms, and working spaces using asbestos materials in deck tile and bulkhead construction

Enclosed Environment Asbestos Exposure

Submarine service concentrated asbestos exposure in an enclosed environment with limited ventilation. Submariners who lived and worked in the vessel’s pressure hull for extended submerged patrols were continuously present in spaces where asbestos-containing materials were part of the structural fabric of the vessel. Diesel exhaust gases at high pressure during snorkel operations could disturb asbestos insulation on exhaust system components.

Postwar Service

Many Gato and Balao class submarines continued serving into the postwar era, with numerous hulls receiving GUPPY (Greater Underwater Propulsion Program) modifications that streamlined the conning tower and improved battery capacity. GUPPY conversions retained the original diesel-electric propulsion systems with their asbestos-containing components, and crew members who served aboard GUPPY-converted submarines through the 1950s and 1960s continued to have asbestos exposure from the original construction materials.

Key Builders

Primary Gato and Balao class builders whose vessels appear most frequently in the asbestos record include Electric Boat (Groton) — builder of approximately 74 hulls — Portsmouth Naval Shipyard — builder of approximately 32 hulls — and Mare Island Naval Shipyard — builder of approximately 17 hulls. Asbestos exposure documentation from these builders’ vessels appears extensively in the publicly filed asbestos litigation record.

VA Claims for Submarine Veterans

VA presumptive service connection under 38 CFR § 3.309(d) covers asbestos exposure aboard Navy submarines. Veterans who served in engineering or other ratings aboard Gato or Balao class submarines during or after WWII and have since been diagnosed with mesothelioma, asbestosis, or asbestos-related lung cancer may qualify for VA disability benefits.

Source notes: equipment-manifest entries (where shown) are sourced from public-record BUSHIPS (Bureau of Ships) documentation, NARA archives, and the public asbestos litigation record. Manufacturer attributions link to documented asbestos-product histories on AsbestosIndex.com where available. Nothing on this page constitutes medical or legal advice.