The Dusseldorf (FLB 2) model fire boat kit was originally produced by Robbe and now sold under the name Krick. The kit is based on the original configuration as the fire boat was built in 1965. In 1979 (well over 40 years ago) the original Dusseldorf was significantly modified and one of the modifications was the hull being lengthened significantly. The increased length is about 200mm (8 inches) in the model's hull.
In order to increase the hull's length it had to be cut into two pieces (across the beam near the middle (lengthwise). In the video () of this process you will see the steps I used to modify the ABS hull.
Additional help, information, and updates are posted on my web site: https://lewsmodelboats.org/M-Fire-Boat-Dusseldorf-2-Index.htm
This video may be helpful to others needing to modify ABS hulls as it deals with cementing and filling ABS including adhesion (weld type) with ABS 3D printed parts, and styrene, both extrusions and sheet.