The heart of marine vessels lies not just in their sturdy exteriors but in the complex machinery that powers them through the relentless waves. Among these, the alternator stands out as a critical component, generating the electricity needed for various onboard systems. Yet, even the most robust parts wear down, necessitating a procedure known as alternator rewinding. At Grandweld Shipyard, this isn’t just maintenance; it’s an art form, combining precision, expertise, and technology to breathe new life into marine alternators.

Understanding Alternator Rewinding

Alternator rewinding involves replacing the worn-out electrical winding of an alternator, essentially refurbishing it to restore or even enhance its efficiency and lifespan. This process is crucial for preventing failures at sea, ensuring vessels remain operational and safe. It’s a specialized task that demands a high degree of skill and precision, qualities that Grandweld Shipyard brings to the table with its state-of-the-art facilities and experienced technicians.

The Grandweld Approach to Rewinding

At Grandweld, alternator rewinding begins long before the old windings are removed. It starts with a commitment to quality and precision, employing semi-automatic winding machines and a team of skilled technicians who bring unparalleled expertise to each project. Our process is not just about repairing; it’s about enhancing performance and durability using the finest materials, including genuine bearings and Class H varnish.

Step 1: Initial Assessment and Disassembly

The process kicks off with a thorough assessment, diagnosing the alternator’s condition to pinpoint issues. Our technicians then meticulously disassemble the unit, carefully labelling and storing each component to ensure a flawless reassembly. This initial step is crucial, setting the stage for a successful rewind by preserving the integrity of every piece.

Step 2: Removing the Old Windings

With the alternator disassembled, the focus shifts to removing the old, worn-out windings. This delicate step requires precision to avoid damaging the alternator’s core, a challenge our experts meet with finesse, ensuring the core’s integrity and the success of the rewinding process.

Step 3: Winding Preparation

The heart of the rewinding process is the preparation of new windings. Using semi-automatic winding machines, we ensure each coil is wound with exact precision, using wire and insulation of the highest quality. This not only guarantees the efficiency of the rewind but also its longevity, with each winding tailored to meet the specific demands of marine operations.

Step 4: Applying Class H Varnish

After winding, the coils are dipped in Class H varnish, enhancing their durability and resistance to the high temperatures often encountered in marine environments. This step is vital for protecting the windings against moisture, dust, and other elements, ensuring the alternator’s performance and reliability over time.

Step 5: Reassembly and Testing

With the windings prepared and treated, the alternator is meticulously reassembled, incorporating genuine bearings to ensure optimal performance. But our commitment to quality doesn’t stop there; each alternator undergoes rigorous testing, from load tests to inspections, guaranteeing that it meets our high standards and is ready to face the demands of the sea.

The Impact of Precision Rewinding

Through the meticulous process of alternator rewinding, Grandweld Shipyard not only restores alternators to their original condition but often enhances their efficiency and durability. This precision work leads to significant cost savings for our clients, reducing the need for frequent replacements and ensuring the reliability and safety of their vessels.


Alternator rewinding is more than a maintenance task; it’s a critical investment in the longevity and efficiency of marine vessels. At Grandweld Shipyard, we pride ourselves on our commitment to precision, quality, and innovation in every rewind we undertake. By choosing professional alternator rewinding services, vessel owners can ensure their ships remain powerful, efficient, and seaworthy for years to come.