USS Massachusetts completes Initial Sea Trials

As China’s shipbuilding plans show no signs of slowing down, progress into service announcements of US submarines like the USS Massachusetts are increasingly important.

The United States Navy’s nuclear attack submarine fleet has moved a step closer to gaining a new vessel, with defence contractor HII announcing the successful completion of initial sea trials for the Virginia-class attack submarine, USS Massachusetts (SSN 798). 

HII’s Newport News Shipbuilding division confirmed on 7 October that its team, working alongside the Navy, had concluded several days of testing for the submarine. The trials involved comprehensive checks of the vessel’s systems and components, including its first submergence and a series of high-speed manoeuvres both on the surface and submerged.

“Our entire team at Newport News Shipbuilding understands the importance of delivering capability to our fleet,” said NNS President Kari Wilkinson. “Proving capabilities through this first sea trial for Massachusetts is an important step in demonstrating this and we are honoured to support the mission.”

The Massachusetts, the 25th submarine in the Virginia-class, was christened in May 2023 and is set to be the 12th of the class delivered by Newport News Shipbuilding. Further testing will be undertaken at the shipyard before the vessel is formally delivered to the US Navy.

Virginia-Class overview

The Virginia-class (SSN 774) programme is a crucial national security asset designed to provide the U.S. Navy with a flexible, multi-mission stealth platform to replace the ageing Los Angeles-class attack submarines. The programme has undergone substantial evolution, with key changes organised into distinct production ‘Blocks’ to enhance capabilities and reduce costs. The initial Block I and Block II boats established the baseline design, featuring a fly-by-wire control system, photonic masts replacing traditional periscopes, and a vertical launch system for 12 Tomahawk missiles. The first major structural redesign came with Block III, which replaced the 12 individual VLS tubes with two larger Virginia Payload Tubes (each holding six Tomahawks) and introduced the Large Aperture Bow (LAB) sonar array, significantly changing the boat’s forward section for cost reduction and improved acoustic performance.

The focus then shifted to efficiency with Block IV, which implemented design changes aimed at increasing the submarine’s operational availability and reducing maintenance requirements, thereby allowing for an additional full deployment over the boat’s lifespan. The most significant increase in warfighting capability arrived with Block V, which introduced the Virginia Payload Module (VPM). The VPM is an 84-foot hull section added to the middle of the submarine that incorporates four large-diameter payload tubes. This dramatically boosts the vessel’s strike capacity, allowing it to carry up to 40 Tomahawk missiles or deploy large unmanned underwater vehicles, ensuring the class remains a potent, multi-mission platform for decades to come.

Key facts:

• Inception: The procurement of the Virginia-class submarines began in Fiscal Year 1998. The goal of the programme was to create a more affordable alternative to the costly Seawolf-class submarines.
• Main Contractors: The programme is executed under a unique teaming arrangement between two primary shipbuilders:

• General Dynamics Electric Boat (GDEB), which acts as the prime contractor.
• Huntington Ingalls Industries – Newport News Shipbuilding (HII-NNS), which acts as the major sub-contractor.

• The original lead ship, USS Virginia (SSN 774), was delivered in 2004 and the class achieved Initial Operational Capability (IOC) in March 2007. The second-of-class, USS Texas (SSN 775), was the first delivered by Newport News.
• The programme has been in Full Rate Production (FRP) since October 2010, aiming for a production rate of two ships per year.

Calibre comment: Growing pains

Comparing military capabilities is always a fraught and frustrating process. The simple fact is that comparing numbers of vessels or tanks does not provide much information. There are multiple cases of smaller and less well-armed militaries holding much larger forces at bay, and even defeating them. With that in mind, it is important to note that the US is watching China’s shipbuilding with considerable unease. When compared to its own output, it is clear that China is able to out-produce the US and that it is planning to increase its production. This makes the continued smooth development and entry into service of things like the USS Massachusetts very important as it shows that the US is still committed to its most potent capabilities. 

By Sam Cranny-Evans, published on October 8, 2025. The lead image shows USS Massachusetts at sea during its initial sea trials. Credit: Ashley Cowan/HII.