SubMayRine 2026: The LEGO ARA Santa Cruz Submarine MOC (The Last Surviving TR-1700)

She was the lead ship of her class, the elder of two sisters, and the only one that survived. The ARA Santa Cruz (S-41) is still in existence today, a living counterpart to the ARA San Juan, which was lost in the South Atlantic in 2017. SubMayRine 2026 continues with her story.

SubMayRine 2026: Week 1

Following the reveal of the ARA San Juan MOC in Week 1 of SubMayRine 2026, the second submarine of the event is her sister ship: the ARA Santa Cruz (S-41). Where the San Juan post was shaped heavily by tragedy, the Santa Cruz carries a different kind of weight: she is the sole surviving TR-1700-class submarine, the lead ship of a class that was intended to number six boats, and a vessel whose life extension programme was underway at the very moment her sister disappeared forever.

The two MOCs were designed together as a natural pair, and building both gives you the complete TR-1700 class as it existed in Argentine service, and the only two submarines of their type to be ever completed.

The ARA Santa Cruz: A Brief History

The ARA Santa Cruz (S-41) is a TR-1700-class diesel-electric submarine of the Argentine Navy, built by Thyssen Nordseewerke in Emden, West Germany, under a 1977 contract. She was launched on 28 September 1982 and commissioned on 12 October 1984, making her the lead ship of the TR-1700 class and the first to enter Argentine service, a full year before her sister the San Juan. The TR-1700 design was built for long-range operations in the South Atlantic, with an emphasis on high submerged speed. At 25 knots submerged, these were among the fastest diesel-electric submarines in the world at the time of their construction.

The TR-1700 programme originally called for six boats, the first two to be built in Germany, and four more to be constructed locally in Argentina under a technology transfer arrangement. However, only the Santa Cruz and the San Juan were ever completed. The four other Argentine-built boats were cancelled in the early 1990s as the country's economic crisis made the programme unsustainable. Santa Cruz and San Juan thus became the only two members of their class to ever sail.

Santa Cruz received a mid-life modernisation at the Arsenal de Marinha shipyard in Rio de Janeiro, Brazil, between September 1999 and 2001, with replacement of engines, batteries, and sonar systems. In June 2014, she ran aground near Buenos Aires while being towed to the Tandanor shipyard for maintenance. Luckily, she was refloated without reported damage.

In September 2016, she began a further renovation and life extension programme at Tandanor, involving a full battery replacement, periscope and snorkel overhaul, engine revision, and some general systems upgrades.

The Survivor: Santa Cruz When San Juan Was Lost

When the ARA San Juan disappeared on 15 November 2017, her sister ship the Santa Cruz was not at sea. She was in the Tandanor shipyard in Buenos Aires, deep into her life extension refit: her batteries stripped out, her systems partially dismantled, her crew ashore. She could not have sailed to assist in the search even if ordered to do so.

The loss of San Juan left Santa Cruz as the sole surviving member of her class. In the years since, Santa Cruz has remained the subject of ongoing maintenance and refit work, her return to active service repeatedly delayed by the same budget pressures and technical challenges that plagued both submarines throughout their service lives. 

But building both the Santa Cruz and the San Juan MOCs side by side is, in a small way, a way of keeping both of them together.

The Bobby Brix ARA Santa Cruz MOC

The ARA Santa Cruz MOC was designed as the direct companion to the ARA San Juan, and at 1:260 scale the two models are identical in dimensions, as they should be, given that the real vessels were built to the same design. The external difference that distinguishes Santa Cruz from San Juan in the MOC versions is the propeller: where the San Juan carries a standard scale-model "tan" propeller, the Santa Cruz features a silver-coloured propeller, a visual detail that allows model builders to easily differentiate between both models.

On the inside, several SNOT (Studs Not On Top) bricks have been recoloured compared to the San Juan version, making the internal build sequence easier to follow and reducing the chance of confusion during assembly. While it might seem as an experimental approach, the use of lime, red and blue colours on the inside will allow any MOC builder to place the bricks right where they need to be, a common practice used by LEGO in their own products and building instructions.

What's Included in the Building Instructions

As with the ARA San Juan, the Santa Cruz is available in two versions. Both include a full step-by-step PDF building guide and XML and CSV parts lists for easy sourcing via BrickLink, Brickowl or any other website you use to buy LEGO parts.

The submarine-only version uses just under 200 pieces and is the cleaner display option if you want the model standalone or integrated into a wider scene.

The submarine with display stand version pairs the model with a dedicated stand, making it a more complete shelf piece and a perfect way to display both the Santa Cruz and the San Juan on matching stands side by side.

Both are available now in the store via the links below.

Who Is This For?

The LEGO ARA Santa Cruz MOC is the natural companion to the ARA San Juan and the two are best built and displayed together as a complete TR-1700 Submarine Class. It's a perfect fit for LEGO naval and submarine MOC builders, followers of the Bobby Brix SubMayRine series, military history enthusiasts with an interest in Argentine naval history and Cold War-era diesel submarines, or just pretty much anyone who wants to honour both vessels of a class that was always meant to be six, but ended up as two.

SUBSCRIBE TO THE BOBBY BRIX CHANNEL FOR MORE!