I like my downrigger cables at a 45-degree angle (or a little less) when fishing with flashers, not straight up and down. When I'm trolling silver horde plugs for kings I go slower but still have a little angle on the cables. I usually don't fish with dodgers but you don't want to go so fast with dodgers that they turn over (just a nice side-to-side swing).

Of course, the 45-degree angle assumes I've got about 90' of cable out with 10-12 lb downrigger weights.

What I'm still looking for is a simple and consistent way to calculate how deep my gear actually is given the angle on the cable at a certain speed. I also wish somebody had an accurate picture of the line and cable blowback and curve. Does the cable curve to look like a quarter-circle (like going from 12 o'clock to 3 o'clock around a clock?)