Steam vs. Electromagnetic Aircraft-Carrier Catapults

The real fight is not simply old technology versus new technology

Draft date: August 14, 2026
Estimated reading time: 2.5 minutes

On August 13, President Donald Trump directed the U.S. Navy to use steam-powered aircraft catapults on the future USS Doris Miller, the fourth Gerald R. Ford-class carrier, instead of the Electromagnetic Aircraft Launch System, or EMALS.

The argument is often reduced to proven machinery versus complicated new technology. That misses the harder question: Which system performs better, and what would it take to redesign a carrier already built around EMALS?

Same job, different machinery

A carrier jet has only a few hundred feet of deck in which to reach flying speed. A catapult supplies the final push by accelerating a shuttle connected to the aircraft's launch bar.

A steam catapult sends high-pressure steam into cylinders beneath the flight deck. The steam drives pistons attached to the shuttle. Its main advantage is maturity: the Navy has decades of operating experience, trained maintainers and known repair procedures.

But steam is not simple. It needs heavy machinery, extensive plumbing and fresh water. The Navy says each launch consumes about 125 gallons of fresh water. Steam also provides less precise control over acceleration, a drawback when launching aircraft of very different weights.

EMALS replaces the steam-driven piston with a linear electric motor. Computer control gives operators smoother acceleration and more accurate end-speed control. According to the Navy, the system is designed to launch a wider range of aircraft with less airframe stress while reducing maintenance, staffing, heat and water demands.

Those are real advantages. They do not settle the reliability question.

Reliability is still contested

EMALS had serious development problems. The Pentagon's latest unclassified operational-test report says its reliability and maintainability still hurt flight operations, and that the crew continues to rely on off-ship technical support. The report also says hardware and software upgrades have gradually improved performance.

EMALS is no longer just a test system, however. By March 2026, the USS Gerald R. Ford had completed 36,863 EMALS launches, according to Pentagon figures reported by Reuters.

Both facts can be true. Tens of thousands of launches prove operational use; they do not prove that the system meets the Navy's reliability goals. Steam has the opposite profile: a long service record, but substantial maintenance, heat, weight and water costs.

Changing the Doris Miller is a different problem

Ford-class carriers were designed around far greater electrical generation and EMALS as a foundational system. Switching to steam is not an equipment swap. It could affect internal spaces, piping, controls, structural interfaces, staffing and the construction sequence.

General Atomics says production of the Doris Miller's EMALS equipment is already nearly 50 percent complete. Reuters reports that changing the design is expected to cost hundreds of millions of dollars. A detailed redesign, final price and schedule impact have not been made public.

That separates the debate into two questions: Which catapult belongs on a clean-sheet future carrier, and which belongs on a Ford-class ship already designed around EMALS? Steam could win the first argument without making a late switch on the Doris Miller the lower-risk choice.

Bottom line

Steam offers maturity, fleet familiarity and well-understood repairs. EMALS offers finer control, lower water and heat demands and room to support a broader mix of aircraft, but its reliability case remains unfinished.

The choice should turn on comparable data for availability, repair time, staffing, aircraft stress and lifetime cost. Until the Navy releases that evidence and a detailed redesign plan, there is no honest basis for calling either option an easy win.