I've had to DR my way home from a dozen offshore fishing locations, some as far as 70 miles from the coast. The biggest problem is not knowing all the parameters you're faced with, tidal currents, wind drift, etc... There's a spot known as the Parking Lot, a good size lump rising up from the Atlantic's floor that is located about 45 miles southeast of Chincoteague, VA. It was a great location to catch big bluefin tuna, some weighing in excess of 200 pounds.
My boat at the time was an 18-foot Starcraft Mariner, an aluminum center console boat with a 75-HP Johnson outboard. The boat was really fast, skipped along at speeds to 45 MPH on flat water, but when you're in the ocean those days are really rare. The navigation instruments consisted of a chartbook, compass, and a Loran-C. Loran-C provided an accuracy of 1/100th of a nautical mile, which was just fine for most purposes. However, when you're 45 miles offshore and a thundershower comes over the western horizon, that Loran-C becomes useless. A message came across the screen that said "No Signal."
I fired up the outboard, pulled in the fishing gear, and DR'd my way toward Chincoteague Inlet. The rain came down in torrents, lightning flashed in sheets, which is really scary when you're dodging bolts in an aluminum boat with a half-dozen graphite fishing rods sticking up in the air. When I finally was in sight of land, all I saw was miles of endless sand in both directions. At this point, I figured that the earlier winds were from the southwest, therefore I probably drifted north a few miles. It turned out to be a good guess--I was about three miles north of the inlet.
For the most part, DR, at least in MHO, is a wild-assed guesstimate, particularly when you really don't have accurate information of all the variables involved in setting a course to your destination. In a powerboat, I think it was not as difficult as it would be in a sailboat. In either boat, however, I manually steer all the time and never had a problem holding a solid compass course.