When the U.S. Navy Blue Angels come to the area we hear about “Mach Speed.” Mach 1 is equal to the speed of sound in air. In general sound travels faster in warmer air, and for normal and dry conditions and a temperature of 68 degrees Fahrenheit, the speed of sound measured at sea level is 768 mph. That little tidbit of knowledge will not help you catch more fish. Applying the same sort of science to “Mack Speed,” however, will. Should lures travel faster in warmer water? Based on a review of logbook notes, Mack Speed — the speed in mph needed to catch more Mackerel — is equal to the water temperature of the Chesapeake Bay minus five divided by 10 plus or minus 0.3. (Editor’s Note: Huh??)

charting mackerel trolling speeds
Find the perfect Spanish mackerel trolling speed and you'll reduce by-catch while boosting the Spanish catch.

During the first few weeks of August 2019 I was not catching mackerel and then I got a tip that started it: troll at eight mph.

Log Excerpts

  • August 16, 2019: Trolled at eight mph and caught a mess of mackerel.
  • August 17, 2019: Went out with Angler in Chief, and we got a few hits, but then I suggested bumping up from seven to eight mph — and we soon had multiple fish on. (Editor’s note: Truth!)
  • August 23, 2019: If I slowed down, I would catch bluefish. And if I really slowed down, I would catch rockfish.
  • August 30, 2019: The water temperature dipped slightly and I noticed they were hitting a bit slower. Started to think about this correlation in my engineer’s mind (along with the recipe I was going to use to cook those fish, the beer I was going to drink, wondering why my car stalls when I honked my horn stopped at a light in 90-degree weather, and is it the duration of the wind from one direction or fetch (distance travelled) causing these waves....
  • September 17, 2019: Eight mph no longer works…?

As a “validator of data,” which an engineer often has to do, I created the table after reviewing my notes and pictures. The math creates the Mack Speed rule of thumb which is so easy that even the Angler in Chief can do it. (Editor’s note: Hey, wait a sec…)

Subtract five from the water temperature and divide by 10.

An example:

86 - 5 = 81

81 / 10 = 8.1

Mack Speed = 8.1 mph

spreadsheet of mackerel trolling speeds
These 2019 numbers have been backed up by at least five trips in 2020 - the Mack Speed formula works!

Naturally, past performance may not be indicative of future results, and individual results may vary due to all sorts of reasons such as the accuracy of your fish finder (for speed and water temperature), turns made while trolling, the ability to note speed when fish on, water current, waves, and wind to name a few. Still, consider the ideal speed as the target to catch the most mackerel and do not fret if you can’t always maintain it. As long as you stay within that range a dozen mackerel are waiting for you. Of course, you will still catch some fish outside the Mack Speed range — but not as many.

holding a Spanish mackerel
That author holds up a Spanish mackerel, soon to be dinner.

- By Walt Tomczykowski