I've read that American and German sailors, when on ships at sea, wear utilitarian work-type clothing or even civilian clothes. What would a Soviet sailor wear? So far I couldn't find any references.

US sailors used to wear dungaree uniforms for general duty aboard ship -- dark blue pants and a medium blue shirt -- or a dark blue overall. Since the craze for digital camouflage uniforms hit, dungarees and work overalls were replaced by a blue-and-grey digital uniform in both pants-and-jacket and overalls. These began to be replaced in 2013 with dark blue outfits treated with flame retardant after the abysmal performance of the 'blueberries' when exposed to flame was identified.

Soviet sailors aboard ship would have worn the basic work uniform, dark blue pants and jacket with hanging collar over a striped shirt here in color, but have in recent years adopted a dark blue pants and jacket working uniform loosely similar to the US working uniform, but with what appear to be visibility stripes across the chest and around the wrists.