Vintage work crew photos

[Toolmaker51]

What is the timer for?

By timer, I believe you refer to the clock looking device high up the mast. That's a range to target signal, aka shot clock or concentration dial, aiding other ships in formation. By observing and comparison, elevation could be regulated somewhat better. Each ship made own corrections for direction, wind and surface speed. More at https://hoover.blogs.archives.gov/20...-like-a-clock/
Disappointed same phrase didn't appear in wikipedia