You’re a pro grower and there is a very high probability that a chunk of your hard earned dough is going to be plunked down on some type of vinyl coated wire gear. Knowing how a quality marine grade mesh is designed, and put together, will give you insight to maximize the service lifecycle of this stuff. Understanding the selection, care and feeding of your vinyl mesh is going to keep money in your pocket longer. Marine grade mesh is a very different product than the green coated fencing stuff in the big box joints.
Making this mesh isn’t your dog, however a general understanding of the construction and how it survives in the bay will help you run your farm in a way to maximize the service life of your equipment.
The theory is pretty simple, stop the electrical activity. This is what turns our base material, iron, the element “Fe” on the periodic table of elements, into the compound “FeO2”, our nemesis Mr. Rust. Be aware that your steel is only a dressed up version of iron.
Like protecting your boat the first thing is an anode, a less noble sacrificial metal, zinc, it corrodes away taking the bullet as it were for you props, rudders, and outboard. You clamp it to the boat, for the wire we galvanize it, just dunk it in, and drag the mesh through a kettle of molten zinc. The process known as hot dip galvanizing, which has become the desired method for marine grade. The rest of the process is designed to make the zinc last longer. Happy zinc, happy steel.
Just putting vinyl over the now galvanized wire makes good fencing, but really lousy marine wire. The vinyl does encapsulate the mesh, but loose fitting like bell bottoms, thus allowing the salt water to get between the two, cranking up the electrical activity.
The intermediate process before the vinyl is the application of a bonding agent that in essence super glues the vinyl to the galvanized mesh. This excludes the possibility of the sea water penetrating under the vinyl, insulating the steel from electrolytic corrosion. The original vinyl wire mesh in the 70’s used lacked the bonding process and compared to todays product the service life was about half.
Okay so that’s what you’re buying. Lobstermen have been building traps out of it for over 40 years. It has proven to work in the marine environment, but how long does it last? That’s a pretty simple, and just about impossible to answer question at the same time. It’s not the fact that the arrow finds the bullseye, it’s the archer that gets it there.
Lifespan varies hugely in different operations, in the lobster industry for example we have seen that owner operated vessels usually get a much longer service life from their traps than boats with absentee owners, using hired crews. The crew has no investment in the operation and just want to get through the trip and get home. Wham Bam. pay me. Smart owners have established a bottom line bonus system, a profit sharing if you will to incentivize the crews to treat the lobster traps and other equipment with more care. Train your newbie’s and have your team leaders enforce that the wham bam is not tolerated. Every nick cut and scrape in the coating accelerates the degradation of the galvanizing as more area is exposed to the conductivity of the salt water.
Watch for better ways in your handling and deployment to maintain the electrical integrity of your vinyl coated mesh, and you can add years just like the captain owned trap boats. We, here at Ketcham’s, have seen new growers dragging cages across our asphalt parking lot to their trailer grinding down the vinyl and zinc to the bare steel. That one act probably cost a year or two from the service life or that gear. We try to give those guys a quick lesson in metallurgy and amortization of capital equipment. Most of the folks get it instantly, while others, unfortunately, not so much. It has been said that nothing lasts forever in salt water, and it is certain that not all the growers will survive. You may not be able to make your gear last forever but it doesn’t hurt for you to try like hell.