The Graf Spee Rangefinder

By Web Team / 13 February 2018 / Insights

In an earlier post a few years ago on this blog, I discussed the Technical Intelligence operation surrounding the recovery of intelligence from the Graf Spee.

The Graf Spee was a German “pocket battleship” scuttled by the Nazis just off the port of Montevideo in 1939 after the Battle of the River Plate. The key part of the story was that the British, posing as scrap metal merchants, purchased the wreck and were able to repatriate a number of items recovered from the wreck by “undercover” operatives posing as scrap metal dealers. The items recovered included weapon systems, armour and components of the German radar system, used to gauge the correct range for the naval guns. Basically they unbolted or cut them off the wreck as it lay, only partly submerged, 7km outside the port of Montevideo. All this was pretty useful to the British in that early part of the war as they tried to judge the enemy’s capabilities.

After writing the post, as a nice example of historical technical intelligence, I essentially forgot about it. But a couple of months ago, pursuing a “bucket list” adventure I was scheduled to board a sailing ship in Montevideo. As I dragged my bulging kitbag from the bus stop at the docks to the wharf where my ship was “parked”, I stopped for a breather at little bench at the entrance to the very wharf where I could see my ship. There were a few of the usual maritime artefacts around, anchors and capstans and the like. On item caught my attention. It was a large T shaped contraption. Both arms seemed to have some sort of optical element at the end of long steel booms. It was painted battleship grey. Blimey, I thought, I wonder…. And I sauntered over to investigate.

With the power of smart phone and google I was able to investigate and, guess what, this was an artefact from the Graf Spee. This was the optical rangefinder, a technology that preceded the radar range finder.  The system was mounted high up above the bridge with an optical system on the end of each boom. The operator brought the images of the target together on an associated apparatus and with a simple algorithm to calculate the angle between the images and some basic trigonometry, the range was calculated. The Uruguayans had recovered this themselves a few decades ago and left it at the dock entrance. Just to prove I was able to actually touch some of the Graf Spee technology, some 78 years after it fought in a battle, here’s a picture, with my kitbag in front.

Thus reminded of my post I hoped to catch sight of the remains of the ship itself but alas we left port after dark and the Graf Spee, such that remains, stayed hidden in the gloom.