Our collective heritage

Boluda towage

Boluda Corporación Marítima was established in 1837 and is a family-owned company. The company started its port tug activities in Valencia (Spain) in 1920.


In 2017, Boluda Towage acquired the German towage companies Unterweser Reederei and Lutgens & Reimers. Subsequently, Kotug Smit Towage became part of Boluda Towage division in August 2019. In February 2021, the harbour & offshore activities of Iskes Towage & Salvage have been acquired. And recently, in December 2021, Boluda Towage acquired the Scottish towage company Caledonian.


URAG history



URAG is a historic European company with 126 years of history, founded to meet freight traffic demand on the Weser River as it passed through the city of Bremen, in the late nineteenth century. Since then it has evolved and specialized, and is currently one of the leading German towage companies, with a fleet of state-of-the-art vessels and a strategic presence in the major German ports. The 18 tugs of the fleet are state-of-the-art vessels with a 100-tonnes bollard pull, specialized in port and offshore towage and maritime rescue.

In 2001, Linnhoff Schiffahrt GmbH & Co. KG, Buxtehude, took over URAG together with L&R Schleppschiffahrt GmbH&Co. KG, RF Forschungsschiffahrt GmbH and WIKING Helikopter Service GmbH to develop an effective mesh of services for near- and offshore markets. 181-year-old company L&R operates on the river Elbe and in the port of Hamburg.

In 2017, the Boluda Towage acquired the companies URAG and L&R.

Kotug Smit Towage

Kotug Smit Towage was established in 2016 through the merger of Kotug (part of Kotug International) and Smit (owned by Royal Boskalis).


The company had a leading presence in 12 ports in 4 European countries (the United Kingdom, the Netherlands, Belgium, and Germany), which has led to increased growth and smarter towing operations with a modern and efficient fleet of around 70 tugs.


Kotug Smit was incorporated in Boluda Corporacion Maritima in August 2019.

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The roots of Kotug Smit Towage, decades of combined track record

Our collective heritage of 350 years of harbour towage is what we breathe and what we are well known for. Our roots are unmistakably European, just like our long history.

In 1842, Fop Smit (Smit Internationale) began providing vessels with a safe and reliable passage into the Port of Rotterdam in the Netherlands. In 2007, Smit Internationale acquired Adsteam’s Liverpool towage operation (Alexandra Towing). In 2008 Smit Internationale required 100% shares in URS. The roots of URS go back to 1870 when captain Henri Gerling established his company “Remorquage à Hélice s.a.” on the river Scheldt. In 1923, the company changed its name into URS.

The roots of Kotug (four generations family Kooren) go back to the initial activities of Antonie Kooren when he built his first tug in 1911. In 1987 Kotug International was established to start harbor towage activities in Rotterdam.



Jacob Visser

Jacob Visser was the founder of the towage company ‘Jacob Visser’. He acquired his first tug in 1928, the ‘Alberdina’ with 40 bhp. In 1930 he acquired a second tug called ‘Neeltje’ (100 bhp). The company towed inland barges loaded with coal from the coal mines in Limburg (the Netherlands) to IJmuiden.


Sleepdienst B. Iskes & Zn

In 1968, Ben Iskes (born in 1944) acquired towage company ‘Jacob Visser’. Like his father, Ben started his maritime career as a deckhand within several towage companies. In 1967 Ben worked on and off on the IJmuiden tugs of Jaap Visser’s towage company. Ben wanted to start his own business and when Jaap Visser heard of these plans, he approached Ben to talk about a possible acquisition. Ben accepted the offer, took over the towing business in 1968 and renamed the company Sleepdienst B. Iskes & Zn.


Ben’s son Jim Iskes started working in the company first as a tug master to gain valuable industry knowledge and experience. Later on, he has taken over the daily management from his father and expanded towage activities in other business areas.


On 16 February 2021, Boluda Corporación Marítima acquired Iskes Towage & Salvage and since then, the company has been renamed Boluda Offshore.

caledonian towage

Caledonian Towage has been acquired by Boluda Towage in December 2021.


Operating in the Cromarty Firth since 1969, Caledonian Towage has emerged as a major player in the towage and marine transportation business. The operation plays an integral part in the success of  Cromarty Firth's reputation as a Premier Deep Water Port and the modern fleet is heavily engaged in a wide variety of towage and support activities. 


The Port of Cromarty Firth was established 48 years ago to serve the oil & gas industry and ensure the region benefited from the North Sea energy boom, due to the discovery of numerous oil reserves.


Caledonian Towage has a proud history, which is dating back to the roots of the JP Knight Group, founded in 1892. This company was originally formed as a London-based tug and barge operator.

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