After the donation to the Gesellschaft zur Förderung des Deutschen Rheinschiffahrtsmuseum Mannheim, the excursion steamer was converted into an exhibition ship.

The Mainz was designed as a monohull ship with a tapered bow, straight steamer stem and a cruiser stern.

After the accident in 1956, the front half of the deck was given a fixed covering, which was glazed on the bow side for wind protection.

The viewing saloon, located on the protective deck in the forward half of the ship, was designed for 84 people and had an all-round paneled outdoor area.

The covered rear area of the deck offered space for 200 passengers, was open at the sides and secured with a railing.

With a maximum speed of 22 km/h (14 mph) when traveling uphill, the Mainz was the fastest passenger ship on the Rhine until the hydrofoil Rheinpfeil went into service.

[3][4] On January 17, 1928, the DGNM ordered a passenger ship from the Ruthof shipyard that was to be suitable for high-speed travel on the Rhine thanks to its hull shape and the optimization of the paddle wheels.

As defects were discovered during the first sea trial on May 4, the planned date for the maiden voyage had to be postponed from May 19 to June 4, 1929 due to the need for reworking.

In the presence of around 200 guests of honor, the Lord Mayor Karl Külb and the Chairman of the Chamber of Commerce Christian Scholz held the ceremonial speeches on the banks of the Rhine in Mainz.

After repairs to the moving parts and the steam boilers at the Cologne shipyard, the ship was used for passenger and freight transport as well as for evacuation trips in the summer months of 1943 and 1944.

[6] The 328 bullet holes caused by machine gun fire from low-flying aircraft were provisionally repaired by KD personnel by September 1945.

The Tour Center Assmannshausen operated recreational trips for soldiers of the US Army with the ship three times a week.

[8] At noon on June 12, 1956, during a turning maneuver of the Mainz near the Koblenzer Pegelhaus, there was a collision with the 800 t freight motor vessel Elise, which was sailing uphill and was steered by an 18-year-old sailor without a Rhine boatman's license.

Shortly after the captain reached the shallow bank in Koblenz-Neuendorf at Rhine kilometer 592.5, which he had intended to evacuate, the ship sank due to the heavy water ingress.

Due to the strong current of the flooding Rhine, the anchor chains broke and the Mainz turned with its bow towards the middle of the river.

[10] During the almost one-year stay at the shipyard due to the accident, the ship was once again completely refitted, and a new rowing chair and a contemporary funnel were installed.

[2] After the 1963 summer season, the newly built passenger ship Loreley took over the express service on the Cologne-Mainz route.

From 1973 onwards, the ship required a great deal of refurbishment due to its age, which led to several visits to the shipyard each year.

When there was again a great need for repairs after the 1980 summer season, the management of Köln-Düsseldorfer decided not to use the paddle steamer, which could no longer be operated economically, in the following year.

[13] In July 1985, the shipping company concluded a donation agreement with the Gesellschaft zur Förderung des Deutschen Rheinschiffahrtsmuseum Mannheim.

On October 17, 1986, the Förderverein handed over the completed ship to the Landesmuseum für Technik und Arbeit in Mannheim (since 2009 Technoseum) in a festive ceremony.

The aim is to technically overhaul the museum ship and give it a new coat of paint so that it can be reopened in Mannheim in the fall after the interior has been renovated.