Editor’s Note: FishTalk’s official Math and Engineering Guru Walt Tomczykowski, better known as Mack Speed Walt since developing an accurate mathematical calculation to predict the ideal trolling speed for Spanish mackerel at any given time (see “Finding the Ideal Spanish Mackerel Trolling Speed”), usually uses numbers to explain stuff. We were blown away by the mackerel thing and shocked yet again when he developed a model to predict size choice guidelines for fishing soft plastics for rockfish season by season (see “Sizing Up Soft Plastic Fishing Lures”). Now, he’s momentarily eschewed math (thanks Walt!) as related to predicting wave height in the Chesapeake Bay, but his observations are still important to consider. We know there are many shoreline anglers among us who may not be so into this article, but the value is too great to boat and kayak anglers to omit from these pages.
May 21, 2024: You plan the afternoon to jig for striped bass on the Bay. You check the forecast and it looks good, with waves of a foot. You grab the proper size lures, rods, and reels and you’re ready to go. You make your way towards the hotspot, but realize these waves are a bit more than one foot. Some may even be approaching three feet, or so it seems as you steady yourself, exercise your core, and make your presentation to the fish below. Beware the fetch!
This has happened more than once to you, me, and every other angler venturing out onto the Chesapeake, and as a reliability, quality, and angler engineer, it is a given that I had to research another rule of thumb. As with my other “rules” it’s to use as a starting point general guide.
Is there already a rule of thumb for wave sizes in Chesapeake Bay? After a bit of research and with the AIC emphasizing his aversion to math, I did find a guideline that applies without too many numerals and no use of the Greek Alphabet, symbols, or mathematical notations. In fact, there are a boatload of wave theory equations in the literature with all the above. However, according to the Virginia Institute of Marine Science (VIMS, Lucy, J., Ritter, T., & LaRue, J., 1979): “A rule of thumb for open waters is, that given sufficient time, wave height will increase one additional foot (0.3 meter) for each seven-knot increase in wind speed.”
No complex equations, no Greek letters — just a practical guideline.
For more fascinating information on weather in the Bay check out the full article on this rule-of-thumb reference, which is easily found online. In the meantime, let’s look at what happened on May 21, 2024. According to the maritime forecast, it looked like the afternoon would be good with waves at one foot. Reality had other plans. Waves were much more than one foot on the south side of Poplar Island, and looking at the data at 2 p.m. the wind reached 14 knots. That would argue for waves of two feet according to our rule of thumb, yet there were three-footers washing by and I now had barely fishable conditions rather than a pleasant afternoon of angling. Why? It had also been consistently blowing from the south for over 12 hours.
Again: beware the fetch! Fetch is the length of water over which a given wind has blown without obstruction. Wind blowing in the same direction, especially south or north in the Chesapeake Bay will, over time, increase wave height even as windspeed remains the same. Here’s a realized observation to the wave height rule: If the wind persists in the same direction for over 12 hours with multiple miles of fetch, add a foot to your wave height. Waves observed on May 21 were larger than predicted in that specific area thanks to wind, time, and the added fetch.
Now, the moral of the story: Use this rule of thumb to prepare a Plan B for when the Bay gets bumpy. While the south side of Poplar was a washing machine, Eastern Bay was calmer (and the north side of Poplar was completely calm) thanks to an interrupted fetch. You can also head for the tributaries and river mouths close to shore to block the wind. Not only will you avoid testing your cushioned helm pad and your core balance, but you’ll also have a better chance of catching fish.
And remember, safety first — no one wants to hit wave after wave after wave, get sprayed, and lose a filling on the way back home!
-By Mack Speed Walt