Guessing a fish’s weight correctly is more luck than skill, and in some circumstances can save you a bit of embarrassment.
Combining various weights allowed testing scales with weights from less than four to over 30 pounds.
There was a fishing club tournament being held one Saturday morning out of the same port where I was fishing. The halfdozen or so boats in the competition were using a popular channel on the marine radio to good naturedly trash-talk one another about how well they were doing, bragging up their catches, bemoaning the ones that got away—all in good sport. One of the competitors excitedly came on the radio announcing he was going to win the big fish award. “I just boated a king that’s way over 20 pounds,” Larry said.
At the weigh-in, Larry’s big one scaled a bit over 18 pounds. You can imagine the banter that ensued for the next few minutes about Larry’s big fish! Still, this little anecdote does point out the importance of having a scale on board a boat. Guessing a fish’s weight correctly is more luck than skill, and in some circumstances can save you a bit of embarrassment.
There are two types of scales available that are easy to use on a boat. Mechanical (spring) scales employ a precisely engineered spring mechanism that stretches or compresses at a controlled rate when various amounts of pressure (weight) are applied. Spring scales have been around for centuries and though mechanical scales are simple technology, they can be quite accurate, depending on the make, model and quality control employed when being built. Then there are digital scales.
Digital scales have been around since the 1980s and employ a complex, hi-tech circuitry to operate. The most accurate scales used to weigh remarkably small items, exceptionally huge items or anything in between (like fish) rely on digital technology these days. The most accurate scales are also remarkably expensive, but there are a bevy of makes and models of digital fishing scales, still quite accurate, available at prices most anglers can afford.
Since the invention of the first scale in ancient times, the question has always been, “How accurate is the scale.” This question led to the one of the first “bureaucracies” ever created by governments and spawned the science of metrology. You’ve probably heard of it as the Bureau or Department of Weights and Measures, depending on your location. The U.S. Government puts their National Institute of Standards and Technology in the Dept. of Commerce. Most states have their own weights and measures metrologists and even some counties and cities send out individuals or teams to ensure when you pump gas at the local fill-er-up you have put exactly 10 gallons in your tank when the pump’s meter reads exactly 10 gallons. They also certify the scales used at retail stores used to weigh meat, produce or other items accurately.
Federal, state and even local governments hire metrologists to check scales used for retail trade.
I checked with a metrologist who works for the Indiana Dept. of Weights and Measures to see what the scale certification process entailed. It’s not rocket science—it’s scale science. The metrologist shows up at a retail outlet to check the scales with a bevy of different weights, the amount of weight depending on the capacity of the scale being tested. The scale certifier’s testing weights are absolutely perfect. The one-pound weight is exactly one pound, not one pound, one ounce, it’s one pound period.
The metrologist sets the one-pounder on the scale he’s certifying and checks the read-out. Then he checks the scale with other weights, up to its capacity and if the scale is good, it gets the certification sticker. With a certified scale you know if you pick a Thanksgiving turkey labelled to weigh 18.09 pounds, that’s what you’ll get.
There’s no reason you can’t check your own scales for accuracy in exactly the same way, other than your metrology kit won’t be stocked with weights weighing exactly one, three or five pounds. I got a tip from a reader for my Basics and Beyond column who went to a supermarket and actually weighed frozen turkeys (which had been weighed on certified scales) with his boat scale. He wanted to know how closely his fishing scale compared to certified weights at the store.
For this article, I gathered three styles and brands of digital scales (Frabill, Rapala and Berkley) along with three brands of mechanical styles—H20X (Academy Sports), Mustad and Ozark Trail (WalMart) brand. I also added an antique pocket scale (over 100 years old) hanging as a decorative item in our kitchen, just for fun.
These seven scales were more than I wanted to sneak into a supermarket to start weighing their frozen turkeys; so instead, I assembled my own kit of known weights. I grabbed a 12-pound downrigger weight and several window sash weights and took them to a nearby Ace Hardware store with certified scales, checked annually by the Indiana Dept. of Weights and Measures. Since the Helpful Hardware Man’s scale was used to weigh nails, nuts and bolts bought in bulk, he had no qualms about weighing my assorted weights. I weighed each weight individually and wrote the certified weight on each one. None weighed the exact weight it was supposed to weigh—but close. The downrigger weight scaled 11.84 pounds, the sash weights were close to their stated weight, some a bit more, some less.
The author tested a variety of brands and styles of scales for ease of use and accuracy.
Back at home, I started with the lightest weight, a four-pound sash (that really weighed 3.95 pounds), then used zip ties to bind individual weights together to make heavier weights. All of the certified-weight sashes and downrigger weight zip-tied together totaled 30.73 pounds. This combination of weights allowed me to cover the weight-range needed for most salmon, trout and walleyes Great Lakes anglers are likely to want to hang on a scale.
I suspended each scale from a roof support beam instead of holding the scales by hand and weighed each of the various combos of weights with each scale. The result was a spread sheet of numbers large enough to keep a statistician happy and most of us very confused. Still, I was able to pull out some useful information.
First, the digital scales were much easier to read than the spring scales. The read out on the digitals were in half-inch tall numbers on an LED screen. The mechanical scales almost required a magnifying glass to read. On the 50-pound capacity Mustad scale the indicator moves from zero to 50 in only four inches of distance. That means each pound mark on the scale is a bit more than 1/16th of an inch apart. On a stable boat, I can make a good guess to the nearest half pound but weighing to the nearest quarter pound is more guess than golly.
The indicator on the 30-pound capacity scale from Academy Sports (H20X Lip Gripper with Scale) pulled down only three-inches from zero to 30, so the pound indicator marks were 1/10th inch apart— slightly better than the Mustad. Actually, the Walmart scale with a dial indicator was the easiest to read because if you were to measure the distance lineally, the scale’s range is about 5 1/2 inches long.
ACCURACY
The three digital scales I tested could all be set to read out in either pounds or kilograms. I used pounds. The digital readouts on the Frabill scale and the Rapala read out in pounds out to two decimal places, the Berkley scale showed pounds/ounces. For instance, the 3.95 pound (certified weight) sash weight weighed 3.98 pounds on the Rapala 50 lb. Digital Touch Screen Angler Model scale while the display on the Berkley Big Game Lip Grip Digital Scale rounded the weight up to 4 pounds, zero ounce on its LED readout. The Frabill scale readout for the same weight showed 4.08 pounds which is still less than an ounce off the certified weight.
Weighing fish while on a boat is common, but can’t really “nail it” to the nearest ounce.
How about weighing the heavier amounts? None of the scales matched the certified weights exactly, but all of the digital readouts came in within an ounce of being spot on when weighing my self-certified weights. That accuracy is certainly close enough for me and probably most anglers. Actually, the mechanical scales “mostly” weighed with accuracy to satisfy most anglers. I don’t much care if the king salmon I hang on my spring scale shows a bit over 22 pounds or just under 23. At least I know it’s not 18—like Larry’s tournament entry turned out to be. For “preciseness,” however, stick to digital scales.
The downside to digital scales is they require batteries and batteries run down. Older digitals I’ve owned had to be manually turned off and if I forgot to hit the power down button or if the scale bounced around in the boat and accidentally powered up, there was no power up the next time I needed it. All three digital scales I used for this article will automatically shut down after being powered up for several minutes.
I’ve also had digitals that showed the difference between waterproof and water-resistant. I don’t weigh every fish that comes over the transom of my boat, but when someone catches something that is “scale-worthy,” I want a scale that isn’t waterlogged, corroded or needs batteries.
Digitals are available at many price points, as are mechanical scales. However, the digitals are, by and large, more expensive than mechanical scales—much more than the $5.00 dial scale I bought at Walmart.
Several years ago, after a few dead batteries or other digital failures on my boat, I switched to the 50-pound Mustad mechanical scale. Wet or dry, it was always ready to use and I knew I could get a “good-enough” reading of the big fish someone just hauled aboard. If I walleye fished more than I do, I’d get a 10-pound capacity, easier to read spring scale.
Some scales come with extra features like a built-in measuring tape.
How accurate are mechanical scales? When I switched to the Mustad Scale several years ago I performed a rough calibration test on it. That test wasn’t as comprehensive as the one I subjected it to for this article, but the initial test showed me the scale under-reported what was being weighed by about ¾ of a pound. If the scale showed a fish I was weighing to be a bit over 17 pounds, I’d call it an 18-pounder—good enough.
The checks I made with this scale with the assorted weights for this article confirmed my previous test and also confirmed that the error was consistent over the scale’s total range. The 3.95 pound weight scaled a bit more than 3 pounds using the Mustad; the 30.73 pounds of all the weights zipped together pulled the indicator very close to the 30-pound mark.
The H20X Lip Grip Scale was about the same as the Mustad, showing weight readings about ¾-pound less than the actual weight across the range of weights I tested. Neither of these mechanisms could be adjusted, but I have seen some mechanical scales which could be adjusted. If you use a mechanical scale, certify it at Ace Hardware or check it with frozen turkeys at the supermarket.
Surprisingly, the antique Salter Pocket Scale I pulled off my kitchen wall—perhaps 100 years old—with a three-inch travel from zero to 25 was the most accurate of the mechanical scales. The Walmart scale’s dial read-out was the easiest-to-read of the mechanical scales but it was erratic in its accuracy. The 3.95 pound weight scaled only 2.5, but the accuracy increased as it heavier weights were hung on it. The heaviest (30.73 pound) weight scaled 31 pounds on the dial.
Frabill’s Witness Net allows fish to quickly be weighed just seconds after it’s caught.
USING HAND-HELD SCALES
I took the Berkley boca-grip style digital scale with me on my last trip to Lake Erie. My fishing partner caught a scaleworthy walleye. The lake was almost slick calm; probably as good of conditions one could get for weighing a fish on a boat. He clamped the lip-grip mechanism on the walleye’s lower jaw, hefted the fish, looked at the read out and said, “4 pounds, 13 ounces…whoops; 5 pounds, three…, whoops; five-eight….”
I told him, “Hold it a little longer, it will soon be a six-pounder!”
This points out one thing anyone who has weighed a fish on a boat knows. It can be close, but it won’t be perfect, regardless of the accuracy of the scale. Even on an almost steady deck, the weight will fluctuate with a bit of motion, whether the motion comes from the waves or just from suspending the fish and scale at arm’s length. A flip-flopping fish makes weighing even more inaccurate.
If you are planning to release the fish, weigh it as best you can and get it back into the water as quickly as possible. If the fish is going into the livewell or into an icy cooler, feel free to get a quick weight before stowing the fish, but weigh it again back at the dock for a more accurate weight. If you can hang the scale from a solid support and then weigh the fish, that’s the best scenario. If the scale is accurate, the hanging weight will be accurate.
If you are planning to release the fish, it’s important to do it as quickly as possible and with the least amount of damage to the fish. That’s one of the reasons I was attracted to the Rapala 50 lb. Touchscreen Digital scale. Instead of the simple hook that either crams into the fish’s gills or punches a hole through a thin spot around the fish’s mouth, the Rapala has a “visegrip-like” fish gripper to clamp onto the fish’s jaw. Both Berkley’s Big Game Lip Grip and the H20X Lip Gripper scale are basically “BocaGrip” styles that holds fish securely with no chance of hooking a gill and no need to poke an extra hole in the fish’s mouth.
The Frabill digital scale I used is their new Witness Weigh Net. It has made catch and release (or catch to keep) fish weighing even more simple. Frabill introduced a Knotless Conservation Net long ago. The (somewhat) tangle-free, rubber coated mesh is designed to be easier on a fish than a conventional, coated or uncoated, knotted mesh nets. Frabill put this net on a sturdy rim and then added a built-in scale in the net’s handle. Scoop a fish out of the water then dangle the fish, still in the net, with the handle vertical to check its weight in less time than it took me to type this sentence. The smaller (18” X 21” rim) Witness Weigh Net is sized perfectly for bass and walleye anglers and will do the job on at least the smaller specimens of salmon and trout here on the Great Lakes. The 21” X 24” rim on the larger model is capable of netting most pike and even king salmon. With a handle length of only four feet, however, the Witness Nets are a bit short for most Great Lakes trolling rigs. The scale in the net’s handle will weigh fish to 30 pounds.
OTHER FEATURES
The main feature of all these scales is weighing fish (or other items), but many scales contain other features which may be useful for some anglers. The handle on the Frabill Witness Net has marks etched and painted on the handle, turning it into a ruler to measure the length of the fish. The Walmart scale has a 48-inch retractable tape measure built into the reverse side of the scale.
The indicator needle on the Mustad scale pushes a slider down as it is pulled downward. When the weight is removed, the slider stays in place indicating the maximum distance the needle moved when the weight had been on the scale. This facilitates a quick release if that’s important. Some anglers use this feature to precisely set the drags on their reels. I use it to test line strength and knot strengths by pulling until the line or knot breaks, at which point the indicator shows the precise pull-point when the line broke.
The Rapala Touchscreen scale has a built-in memory which will store the weights of up to eight individual fish. This feature could be useful for tournament anglers, for large groups on a charter or to keep track of the biggest fish for the season. There’s a back-up memory in case the batteries die.
What sort of scale to put on your boat or take with you fishing is up to you. All the scales I tested were reasonably accurate and easy to use. The important thing is to have one when you need it. If nothing else, it will save you the embarrassment of learning that 20-pounder you caught and were bragging-up turned out to be more than a few pounds less than you guessed.
