New problems arose on 14 August 1986, when the command center of "Walrus" caught fire, while it was still on a scaffold in the shipyard. The fire lasted about five hours, and resulted in immense damage to the submarine; the command center was completely burned out. While some equipment could be rescued, most had to be replaced. This delayed the construction of the submarines once again. The costs of the resulting damage was 225 million guilders, which was fully covered by insurance. The exact location, origin and cause of the fire was never established. Presumably, the fire was caused in the vicinity of the corporals and men's washroom by a defect in the electrical work lighting. Repairs were reported as complete in 1987, but had so delayed construction of "Walrus" that the second submarine (with construction number 349) was put into service as the first of the class, with the name HNLMS "Zeeleeuw" (sea lion). HNLMS "Walrus" was put into service two years later. The two other boats were put into service as and (porpoise). The delays meant that , and of the "Dolfijn"-class had to remain in service longer than planned. All the problems, delays and rising costs were eventually dubbed by the Dutch national parliament as the "Walrus-affair". Nonetheless, at the time of their commissioning, the "Walrus"-class submarines were considered to be one of the most modern and advanced conventional submarines in operation.