I had no idea about the story behind the red and blue stripes on the fender, but what I do know, is that L.Smit & Co. had a blue band in the black funnel and "Internationale Sleepdienst" had a red band in the black funnel.
These two companies merged in 1923, so I suppose that this is the reason for these two colours on the fenders.
Maybe, somebody who can confirm this?
Well, yes and no. It was not exactly a merger. Anyhow Smit had a slight edge over Internationale which reflects in the name where to the casual reader Internationale merely reflects Smit's world wide operations. The need for the joining of forces came from the rapid expansion of Bureau Wijsmuller. Anyhow, the deepsea tugs had a blue band on the funnel, the harbour tugs a red one. The reason for the red/blue striping could well be as MarEng states. The yellow/blue dates from when they became Smit International. Again, the blue could come from L.Smit and the yellow from P.Smit, the biggest of the harbour towage operators that were gobbled up. When the intermediary name Smit-VOS was carried for the harbour division at Rotterdam, the tugs had a blue funnel with yellow SV.
Regards - Job (TugDoc)