Arrow purchased Waterman in 1917. These catalog examples are after that. Arrow produced motors for two years prior to the Waterman acquisition according to Peter Hunn's book, and the ad below is from 1915.

• example 1, plate from Arrow catalog
  
  
• example 2, after buying Waterman this Porto rowboat motor was offered by Arrow
  
  
• off topic: want to see what some old literature looks like when I get it and how we can digitally restore it?
  
  
• Below on this page- ads from 1915 - note the design of their logo on the tank so you can compare it to 1916
  
  
• 1916 ads with the changed logo