What does the number next to the depthmeter mean?

[haggis 1982]

Hi!

I'm just wondering what the number next to the depthmeter mean?

http://img51.imageshack.us/i/namnlsb.jpg/

[Mr Arrow]

It maybe the drag setting - sorry been a while since I played this game. If it ranges from 1-5 then it is the drag.