A hardspot is usually very small and is just that, A hard spot on the bottom. It can be rock, clay, or even an old piece of debrise. Usually only one or two big snapper gather on a hard spot. If a snapper isn't there a shark usually is. On a recent alnight hard spot fishing trip, Ronnie on the 36 Contender "AGGREVATED" fished 14 hard spots out in the old yeller area. Out of 14 spots we caught 3 snapper and a hundred sharks. The 3 snapper were all over 22lbs. each.
How to find a hard spot? First of all there is no way you can identify one at speeds much more than 15 knotts.
If you have a good 1000 watt bottom machine and properly placed and installed transducer you might get away with 15 knotts.
At 7 or 8 knots a hard spot looks just like a spike on your bottom machine. The red bottom line will be thin and at the hard spot it will get thicker than tnin again really quick forming a spike. You have to determine wind and current to effectively drop your bait right on that spot. I use at least 20 ounces of weight to get it down fast.
a pipeline inside 30 fathoms looks just like a hard spot when you cross it. If you are able to run down the pipeline it would appear as an endless hardspot.
I'm sure there are hardspots all over the gulf, luckily I have a good friend who is a commercial fisherman (little billy wright). He supplies me with all the hardspots we can handle. He finds them while running from one spot to another at 6 or 7 knots commercial fishing. He can't waste his time trying to grt a big snapper to bite. He needs numbers.
I do know that 3 years in a row the star snapper was caught by either little Bill, or someone on his boat or Bubbas's boat "Good News".
They really know how to fish hardspots.
Capt. Jeff Gerrans