Cables and Weights
The decision to work with manual versus electric downriggers depends on your budget and fishing style. I lean toward electric models to avoid tying up a pair of crew hands when they can go to good use clearing other lines.
Opinions abound about the positives and negatives in regard to the electrical field an automatic downrigger could conceivably put out, but I don't buy into that.
Speaking of cable, don't take the term too literally: We recently switched to 220-pound braided line instead of steel downrigger cable and have enjoyed great success with the setup. The braided line doesn't hum like metal cable, and its thin diameter reduces "blowback" so the weight stays deeper.
Now we come to the great debate surrounding the pros and cons of using weights versus planers on your downrigger for taking baits down. For offshore action, I like weights. Once again, the choice boils down to individual preference and particular situations.
For slow-trolling live baits at extreme depths, I always go with a solid, round lead cannonball weight with a fin of some sort because it drops quickly and tracks true. Z-Wing planers and the like certainly work well for faster trolling at shallower depths. (We're lucky to have this kind of equipment these days; I still remember having to fashion downrigger weights from heavy chain shackles because we could find nothing else.)
When running multiple downriggers off the stern, use pancake downrigger weights with stainless-steel fins. Bend each weight's fins in opposite directions; they act as rudders and force the two downrigger baits to "fly" away from each other. This little trick also makes it nearly impossible for the weights to tangle on turns.
Snubbers and Clips
Always - and I mean always - use a 1- or 2-foot section of elastic material (like a Rubber Snubber or heavy-duty, industrial-strength bungee cord) between the downrigger weight and cable. Whether on manual or electric downriggers, deployment and retrieval generate some start-and-stop, jerky motion. When a heavy ball on no-stretch cable or superbraid line suddenly stops a looooong way down, problems may occur - namely lost downrigger balls, and no skipper can afford to lose his balls.
The choice of release clips becomes a matter of personal preference as well, and a little research turns up plenty of options. Instead of spending a fortune on clips, we make our own releases that work just fine. We crimp a heavy-duty snap swivel to each end of a 4-foot length of 300-pound monofilament. One snap swivel attaches to the downrigger weight, and the other opens to receive the loops of a #64 rubber band, wrapped figure-eight-style around the main line. It's a highly effective, ridiculously cheap way of doing things and a bit old-school, but that's exactly why we like it.