Here we go. This is what a 1:1 scope looks like if you did not include the length of the anchor shank. As mentioned earlier this aluminum shank represents the length of my 35 pound CQR to scale. A true 1:1 would be vertical but the extra length allows some angle to the scope.
Scope is figured as 1 times the depth from your bow chock to the ocean floor. So for a 5:1 scope with 10 feet to your bow from the bottom you'd need 50' of rode or 5 X 10' = 50'. 7:1 would be 7 X 10' = 70' of rode. If your depth transducer is 1' below water and not calibrated for offset don't forget to add this into the calculation. Forgetting to add in bow height is most common and can make a fairly big difference if you leave it out.