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FISH FARMING TECHNOLOGY giving the product the benefits of both materials. In the case of Polymax the rope is composed of Polyethylene and Polyester a combination that highlights flexibility and high abrasion resistance. What we have done is taken a polyethylene rope and wrapped it in multifilament Polyester. This product is slightly more expensive but its benefits in abrasion resistance and at the same time UV resistance (thus delaying the downgrading of the rope) greatly outweigh the extra costs that can add up to a couple of hundred US dollars per cage. Polyester has a higher density than the monofilament polysteel or polyethylene thus could increase the weight of the cage in an unnecessary manner. That is the main reason we have not proposed polyester ropes but we definitely don’t discard that option for customers willing to try it although it would be more recommendable to use the FISA polytar rope.

FISA Polytar ropes

An additional product we recommend for harsh conditions is the Polytar rope that is made of high tenacity polyester but at the same time coated with a tar solution developed by FISA that will work as a lubricant during maneuvering specially with the stretching of the rope in open sea conditions. It is important to mention that we don’t simply tar the ropes but rather the actual twines that compose the ropes so it is not just a top layer of protective tar but also actually a rope produced with tar inside. This protective coating also gives added protection against the UV rays.

Accelerated UV and abrasion resistance tests

FISA quality control department gives great importance to follow up controls of our end products under the most realistic and life resembling situations. Thus we don’t just rely on the theoretical facts and standards relating to raw material but we actually run as realistic as possible a test on the actual finished products such as ropes and twine. An example for this would be our abrasion and accelerated U.V. effect tests. Here we take both netting and ropes with different characteristics through rigorous testing that includes initial “standard” breaking load and elongation tests followed by accelerated abrasion effect machinery and UV accelerating effect equipment in order to retest the products and see the breaking strength, elongation and most importantly the Working load of the product after deterioration due to its use in the real world. This is a comparative test and gives clear indicators as to what products are more adequate for each specific use. As part of our service, we are always glad to receive used products after specified periods of time so we can evaluate the performance and compare the durability of alternative products used in same or similar water conditions. Over the next few months we will gladly share on these pages some more of our extensive experiences including the advantages of using braided knotted netting for tilapia farms in lakes, the use of monofilament polyethylene and SUPRA netting for predator protection, the use of long life twisted knotless SHOGUN netting for bird protection and also some technical advice in cage design and maintenance.

International Aquafeed - July 2017 | 43

Jul 2017 - International Aquafeed magazine