I know that jerk baits are designed for shallower water but how deep will they actually remain effective?

While it is true that jerk baits are better used in shallow water it has been shown that with the right jerk baits you can go as deep as 8 to 10 feet. You will get the best results with them if you use them in this pattern in shallow water; Reel you bait just under the surface of the water while keeping the tip of your rod pointing down, next you will want to use your rod to do a set of fast or quick jerks but be sure to keep the bait in the water while you take up the line between jerks. You can either go with a steady rhythm of jerks or you can go with a retrieve that is a bit on the erratic side. This can be done by using a few long pauses in between a few fast jerks. If you want to go into the deeper water with jerk bait then you might want to use something such as Bomber Long A that has a black back. Some people prefer to use ones that have the orange underside where the sides are gold and silver. This type has been shown to be very effective on both cloudy days as well as clear view days. The shiny sides can help you spot your bait from a far distance when the side flashes when you jerk it. With a flash as powerful as that you can expect to get a bite from good distance. This is where the bait can be used in clear water up to 20 feet deep.