Vesikko had a crew of about 15–20 men, each of them assigned with a specific task. A torpedo NCO and torpedo seaman were responsible for three 1,500 kg torpedoes, Vesikko’s main weapons. They were in charge of loading torpedoes, inserting them in torpedo tubes and taking them out of them, and maintaining them. The torpedoes were loaded in the vessel with a winch and hoist through a latch on the top. Cleaning the torpedo tubes, which had to be done regularly, was one of the most loathed tasks. 

The seaman had to crawl inside the cold tube and remove all the dirt and humidity. The other weaponry was mainly for air defence. In the Winter War, the only piece of weaponry on Vesikko’s deck was a light 7,62 mm anti-aircraft machine gun L-32/36. After the War, Vesikko’s weaponry was strengthened by a 20 mm Madsen automatic cannon.