Matthew and I talked about the fact that you can create a grid for fishing offshore structure in much the same way as you do to fish new flats. The difference with a flat, of course, is that you can 'triangulate' the spot visually; offshore you have to do the same thing with buoys -- but the concept is the same. Draw a grid and use the wind and tidal flow to create a zig-zag drift that effectively covers the entire area you're fishing.
Offshore drifting takes just as much thought and consideration as flats drifting. No, you won't get your boat stuck on the bottom and have to wait hours on end for the tide to come back to float your boat if you aren't paying attention, but when fishing nearshore or offshore wreaks, reefs and hard bottom it is key to stay atop your mark. Even being a couple of feet off the location could be the difference between a great day of fishing offshore or going home empty handed. How to keep from multiple lines from tangling, how weather conditions such as wind and current will affect your drift and keep you on your spot are all key factors in "power drifting offshore"
The shape of structure nearshore and offshore can be used to create a grid that works the same when you're working structure as it does in sixty feet of water. You can work more accurately and effectively with a grid plan.
When fishing over structure you will want to use enough weight to reach the bottom. Staying on top of a good spot will do no good if the bait cannot reach the target at the bottom. To much weight and it becomes difficult to feel the fish, so there is a fine line in choosing a size weight. Pay attention to the current and different size weights on your gear until you find a suitable weight. Keeping one rod with a slightly lighter weight will allow the bait to be farther back then the lines with the heavier weight, using 2 different weights will allow you to fish two different parts of the reef at the same time. At the same time have a line (or two if you are daring) and throw out a flat line (no weight, usually a tasty live treat for a pelagics) For the flat line I like to use a spanish mackerel, large threadfin or a spanish sardine. For the bottom spanish sardines or pinfish work great.
Once you have located your target bottom you will want to mark it with your GPS/Sounder (you have one of these right?) When you slowly troll over the bottom mark the north and south points of your mark then make a east west pass over it again so you have 4 point "crosshair" of your spot. Being offshore there are no visual cues to know if you are off your mark (without looking at your GPS) so by marking the location you know exactly where on the reef/hard bottom you are at any given time. If your GPS is acting up that day you can throw four different marker bouys in the water it will accomplish the same thing. Don't forget as you are cruising over your reef to remember where on the "bottom" the fish are concentrated. Different species of fish will tend to congregate on different portions of the bottom structure, grouper for instance might be on the upstream side of the wreak where as snapper will be in the downstream side of the wreak. Amberjacks, cobia, and permit will tend to be on top.
Wind is the biggest factor offshore as to how your boat will drift over the bottom. When drifting with an outboard engine boat, you must keep your stern into the wind. This will give you the most control of the boat. If you try to keep the nose of your boat into the wind you will have a tough time controlling the vessel over the wreak. Use just enough reverse to keep on top of the bottom you are trying to fish. Pay attention to everyones line and try to keep them as vertical as possible. You want to try and stay stationary as long as you can to give you the best odds of catching fish.
Drifting offshore wreaks, reefs, and hard bottom is a great way to located and fish new spots as well as fish old ones. When you power drift you give yourself the option to move quickly without the worry of pulling anchor. Or the worry about the anchor draging off your location. The key points are to keep enough weight to reach the targets (fish) at the bottom, stay atop your mark, and control the boat by keeping the boats stern into the wind. With these things in mind you could power drift over spots quicker, faster and more efficiently to find the fish.