Have the remains of the Santísima Trinidad been discovered?

-- FROM AFONDO MAGAZINE -- A recent equipment demonstration done by Simrad Spain detected a wreck which, according to early indications, could be the legendary vessel of the Battle of Trafalgar, the Santisima Trinidad.

Last year, staff from Simrad Spain performed a demonstration of a side scan sonar from GeoAcoustics A Kongsberg Company onboard the hydrographic vessel Malaspina operated by the hydrograpic institute of the Spanish navy. They decided to do an in depth study in an area where a KONGSBERG's EM302 multibeam echo sounder, already installed on the vessel, had previously made some discoveries that called for attention. The target is in about one hundred meters depth, off the coast of Cadiz in Southern Spain. Already with the first high-resolution images obtained with the GeoAcoustics Dual Frequency side scan sonar, it was confirmed that this was a reasonably well-preserved ancient shipwreck.

Driven by the excitement of finding and collating historical data on the sinking of the Santísima Trinidad, the team registered and recorded numerous side scan records in order to supply data to the University of Cadiz. The latest reports suggest that this really is the famous vessel, but this still needs to be officially confirmed.

History of the Santísima Trinidad

The ship was built in Havana in 1769 and was the largest warship built to date. Given its large size (length 61.40 m, 52.72 m keel, beam 16.59 m, Depth 8.31 m.; tonnage 4902 tonnes) the ship was known as El Escorial of the seas (El Escorial = a historical residence of the king of Spain).

After being tested at sea, they realized that the vessel suffered from several flaws that were corrected in the shipyards of Ferrol and Cadiz. Such were the changes implemented that she became the only ship in the world with four bridges. The vessel ended up with the following dimensions: length 63.36 m., 54.02 m. clean keel, beam 16.67 m, Depth 8.26 m., measured 2475 tons. The crew consisted of approximately 1100 officers and seamen. In July 1779, Spain and France declared war on Great Britain supporting the American colonies in their War of Independence. The Holy Trinity was the flagship of the Spanish fleet and took part in operations that occurred in the Channel in the late summer of that year. In 1780 the ship took part in the capture of an English convoy consisting of 51 vessels. In 1782 it was sent into the top corner of the Mediterranean, and participated in the Battle of Cape Spartel.

The ship is remembered for its tragic end at the Battle of Trafalgar (1805). At that time, the vessel was under the orders of squad leader Baltasar Hidalgo de Cisneros and Francisco Javier de Uriarte y Borja as Captain of Allegiance. After a hard and heroic struggle, it was captured by the English in a very poor condition, with over 200 dead and 100 wounded. The British worked hard to save the ship and brought her to the British port of Gibraltar, towed by the frigate HMS Phoebe and HMS Naiades. Eventually, however, she sank about 25 or 28 miles south of Cadiz on October 24. Symbolising the end of Spanish power on the seas, the greatest war weapon of its time now remains in the deep sea. The guns were recovered and now lie at the entrance to the pantheon of distinguished seamen.

Equipment used for wreck detection and imaging

The location of the wreck was done using two KONGSBERG systems by while conducting a demonstration onboard the hydrographic vessel Malaspina (owned by the Spanish Navy).

The first contacts were established through a KONGSBERG EM 302 multibeam echosounder that was already onboard. It works with 30 kHz and is specially designed to perform high resolution seabed mapping with a range from 10 to 7,000 meters. The EM 302 is used for geological mapping from coastal areas to full oscean depth, and is a world leading product within this market segment.

One of its most outstanding features is the high resolution of the images provided due to advanced signal processing and a high number of probes (860 probes per pulse). This allows you to target both in emission and reception. It works with three axes stabilized: yaw, pitch and roll. The hydrographic vessel Malaspina is also fitted with a KONGSBERG EA 600 SingleBeam Echosounder (12kHz) and a KONGSBERG Seapath 200 position, attitude, time & heading sensor. Together with its twin Tofiño, services have been performed in most Spanish waters with high performance. It provides sharp and well defined images for locating objects such as cables, wires, etc. that have never before been mapped.

Starting out with the bathymetry data, the project team proceeded the inspection with a dual frequency side scan sonar from Geoacoustics. The sharp images obtained left no doubt: it was an historic sailing vessel in which the bridge was fully differentiated. Since the system is available for connection to a DGPS receiver, we already had the pictures and position of the wreck. The rest is for the historians to decide.

Sonars of this type are ideal for seabed mapping. Its use is spreading increasingly, among private companies and official institutions since it is easy to use and has numerous applications, including civil works, search and rescue, inspection, marine research and archaeology.