Dyneema® fibre has been around for a long time. Developed and patented by DSM of Holland, this fibre is used in the manufacture of strong lightweight ropes, motorbike and many other types of crash helmets, armour plating for the military as well as mesh used in the commercial fishing and aquaculture industries.
The Netting: When "Motueka Nets" first began trialing this netting in the mid to late 90’s, there were a few teething problems; not with the yarn per se but in the manufacturing techniques used at the time.
The only looms available to make both the braided twine and the netting were machines that had tolerances too great for a yarn with virtually no stretch factor: This resulted in twine that was unstable, and because of the strength of the material, knots would slip and the mesh would become distorted. “This put a lot of people off initially and is still a little in the mind set of a few we talk to today".
However, since then, well known international netting manufacturers,Van Beelen also from Holland and suppliers to "Motueka Nets",have installed purpose built state of the art computerised machines specifically designed to manufacture not only the twine used, but also machines to produce a double knotted Dyneema netting that is, we believe, the best Dyneema netting on the market.
Chaff Resistance:The evolution of Dyneema netting is that we used to make bottom trawls with a combination of PE braid in the lower parts, why? because of its "perceived" superior abrasion resistance and cost of replacing Dyneema netting in the wear areas: However!!! Now, with the superior quality of the Dyneema being produced it is less cost effective to use PE because it wears out many times more quickly that the Dyneema it is supposed to be protecting!
Cost Savings ( netting ) One Company,"Talleys" now in their 6th year of using Dyneema trawls across their fleet, has found that the cost of replacement net panels is cheaper per annum using ones made from Dyneema although each panel is much dearer than its PE counterpart!! Reason being, the need for replacement panels is made far less often.
Cost Savings ( engineering ) For the factory vessel fleet we service, “Most of our bottom trawls are made with 2mm braid: We were using 4, 5 & 6mm in PE, so now the twine surface area is often less than 50% of what it used to be: One chief engineer told us that even with twin trawling "there is a noticeable reduction in the load on the main and auxiliaries engines, exhausts temps are down, there’s less shuddering and overall," the ‘old girl’ isn’t working as hard and this means the cost of maintenance is also down as well.”
Cost Savings ( fuel ) The biggest savings have been in the use of diesel fuel, both LFO & HFO When we first started looking at the fuel saving aspects using Dyneema netting, all the companies involved already had fuel flow meters fitted on their vessels: The value of this was that it took any guess work out of how much fuel was or was not being used: "we had actual number" How have those numbers stacked up??? for one 3500 hp vessel we have had savings of as much as 60,000L a trip!
Cost savings ( gear ) Nets made with Dyneema® Netting also spread easier. “We’ve found that door sizes can often be reduced or used on finer settings and still maintain spread. For example, "San Enterprise" operated by Sanford of Timaru: in 2011 started towing a “Motueka” Dyneema trawl, and were able to change from a set of “Morgere” OF16 oval doors of 8.5m² To a set of “Morgere’s” new V3 type doors of 7.5m² : Now not only are they getting the benefit of an easier trawl to tow but the smaller doors are giving them significant fuel savings as well.
Inshore Vessels The success and savings are also reflected with the smaller inshore fleet on vessels with as little as 200hp. ”What we are doing is making trawls of a size equal to what they are towing in traditional PE material : However now they are able to run longer sweeps, get more spread , use less settings on the doors or use smaller doors and do so between 200 – 300 rpm less than formerly: One skippers recent comments were “ with our vessel we always struggled to turn with our gear down, now we can do it with ease.” “We’re seeing fuel savings mostly around 15- 16% but often up to 20%. The higher saving figures come through particularly where the vessels have accurate fuel monitoring systems to record their usage. Another advantage that vessels with less HP have found is that when targeting faster swimming species they normally struggle to catch, these species are now successfully being caught because of the extra speed available.
Overview At the end of the day, successful fishing not only comes down to the amount of fish caught but to keeping the cost down for each kg of fish caught as well!! DYNEEMA NETS HAVE PROVEN TO DO THIS!!
Aquaculture An area of increased production in recent years for Motueka Nets is in the manufacture of fish cages and ‘predator’ nets for marine farms for both Salmon and Bluefin Tuna : Again this is an area where Dyneema netting is proving very successful
“Fish cages when made from traditional Nylon netting depending on size can weigh as much as 5-7000kgs when wet, However when made with Dyneema® these can weigh as little 750kg -1500kgs which remains the same weight whether they are wet or dry because Dyneema is inert and does not absorb water. That’s a huge reduction in weight and it makes lifting, cleaning and repairing these nets that much easier...and safer.”
Added to that is the fact that because of its strength and high resistance to chaffing and cutting it is proving an extremely strong barrier between sharks, Seals and other predators that would normally cut and eat its way through traditional materials