Thanks for the responses.

Here's what I do now -- rig everything up, put the motor in gear at idle, throw everything in with the reel free-spooling, count to 30, then lock up the reel. This puts about 200' of line in the water. I'm guessing that this puts the offering at between 20' and 80', depending on whether it's a banana weight, #0 Jet Diver, or #2 Deep Six diver. I'm running Spectra, so the line shouldn't be arcing too much underwater.

Whaddya think?