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How much zinc makes a fishy boat?

PostPosted: Sun Dec 29, 2019 12:55 pm
by lcharge
One of the biggest misconceptions are that, if you add more zinc, you will have a stronger hull voltage. In some cases, if you add too much zinc, you start to repel fish. I have been working on this for several years now and to the point where I was paying for advertising, offering 'Free Help' to boat owners who had problem boats. This was to have a better understanding and to confirm my suspicions of what makes a boat 'fishy'. The added data was invaluable to me and prompted me to do a comparison study. The study is done on lakes and for trout. Before you start complaining "TROUT", when I developed my Lurecharge system of voltage tuned lures, the first fish that I proved it on was cutthroat trout. Since then, every other species that has been tested has mirrored results to trout. This includes fish from chinook salmon to ice fishing for perch. When a fish is receptive, the ratios are virtually identical regardless of species.
I am doing a study where, instead of using tuned lures, I am using plain sets of identical lures and adjusting the boat's signature to be neutral, negative, or positive. My lures are trolled. one at 30 ft and the other at 100 ft or more behind the boat. In order to have an unbiased outcome, I alternate the lures every strike or two and use several sets of lures without any flashers or attractants. I also try to stay in open water as opposed to having one lure closer to the beach. The boat setup is an unpainted 14 ft Lund with an 8 hp Yamaha with all zincs removed. The results so far are as follows.
NEUTRAL SIGNATURE - 50/50 within one fish (no zincs).
NEGATIVE SIGNATURE - 72% of the fish will strike the 100 ft lure (repelling mode achieved by hanging 25 sq in zinc (exposed surface area) off the stern with twine and not connected electrically to hull).
POSITIVE SIGNATURE - 75% of the fish will strike the 30 ft lure (attracting mode achieved by electrically connecting the same zinc to the hull with copper wire).
The study to date is based on 37 fish strikes. I am hoping to double the numbers in the spring of 2020. I was hoping to collect data throughout the winter, but the fish have essentially shut down on eating. I was going to wait before publishing my data, but thought that some of you might find it interesting prior to spring haulouts and re-zincing.
Many of the anglers that I have talked to are experiencing identical problems. A lot of them have upgraded their boats and/or motors, only to discover that they now only catch about 1/3 of the fish compared to their old boats. The guys that upgraded from older unpainted aluminum boats to new aluminum boats with painted bottoms are now overzinced and repelling fish. This is essentially what I tried to imitate with my boat in NEGATIVE SIGNATURE mode. New outboards seem to have lots of zinc and no exposed metal to protect, especially if the prop is painted. Owners of fiberglass boats are similarly affected when they replace their old outboard motors for new ones. Outboards with bare stainless props, guards or cavitation plates will be fishier. If aluminum hulls were unpainted and there was electrical continuity between the zincs and the hull, the boat would be fishy as all get out. In all cases, zincs need to be way smaller than the proud metal that they are protecting. As an example, my 14 ft Lund is normally pretty fishy, just with the one small zinc at the bottom of my Yamaha. The hull metal to zinc ratio is approximately 1,000 to 1. When I attach the 25 sq in zinc, my ratio goes to about 350 to 1. When I am in this POSITIVE SIGNATURE mode, I have never had so many fish strikes this close to my boat!!!! The math is really easy.
If you want to know where your boat is in relation to it's zinc ratio, here is a test to try. You should be 100% confident that you have a sound bonding system. Move away from the dock and other boats. Have an assortment of zinc anodes ready to attach a wire to. Take your voltmeter on 2 volts dc and attach the negative probe to the bonding system or rudder post. Simply drop the positive probe into the water beside the boat (most are nickel plated probes), note the initial reading. If you have outboards or I/O's, keep your engine running so as to keep the internal engine and engine anodes wet (they are also part of the equation). Now use good sized wire and connect the zincs to the bonding system and lower them one at a time into the water. Note the initial reading and the subsequent readings as more zincs are included. Leave enough time in between zincs to allow the voltage reading to settle. If the readings increase from the initial reading, only add zinc to a point where the voltage stops increasing. You may go a bit over, simply because your zincs will diminish throughout the year. You can also plan on adding more mid season.
If your initial voltage reading does not increase at all, or goes down, you had too much zinc to start with. This can be altered by removing zinc, or installing more proud metal so the ratio gets better. I have found with my tuned lures that they will still attract fish as low as 5 parts proud metal (marine grade aluminum or stainless) to 1 part zinc. Higher ratios than 5 to 1 are preferred.
For the skeptics, if you think that fish aren't that sensitive and you know someone that has a non-fishy boat, just ask them if they can catch fish down at 200 ft depth?
NOTE - In this test, the voltage reading will not be a true hull voltage, but will be helpful for knowing how much zinc to use.