Work has officially begun on our Summer 2026 Pilot Study. We are building the first trawl that we will use to collect marine microplastics samples in the Charleston, SC area's inland and coastal waters. Once building is complete, we will begin testing the trawl on the water.
We are building our microplastics trawl to the design published by Camins et. al (2020) in the scientific journal, Science of the Total Environment. Here is a screenshot of the design from the article:
We began by purchasing the necessary supplies. These included red oak wood planks as well as various fasteners and other pieces of hardware--all in either galvanized or stainless steel. We are building our trawl so that the wings will be removable for easy transport and on-site assembly.
The next step was to cut the pieces of wood needed to build the frame that will be used for microplastics catchment. We will be attaching nets sewn to the design of Camins et. al, and these will also be removal so that we can test nets of different microns.
After cutting the frame, the next step was to drill pilot holes to assemble it. Pilot holes were drilled based on the size of screws purchased.
Each piece of the frame was labeled on both ends to ensure that the same ends would be matched on final assembly.
Where the screw heads will sit, the pilot holes were countersunk to allow for a flush finish. The holes will be sealed along with the exterior of the frame at a later stage.
The next step was to drill holes for the hardware that will attach to the frame. This includes 'L' brackets with bolts and wingnuts for easy assembly/disassembly and eyebolts for attaching the tow ropes that will lead to the towing vessel.
While the eyebolts will be screwed into pilot holes, the holes for the 'L' brackets were drilled large enough that the attaching bolts can slide in and out, but without unnecessary play.
Per the design of Camins et. al, the placement of the 'L' brackets was measured so that the wings will sit at the center of the frame.
After drilling pilot holes, larger holes were drilled to fit the attachment bolts, as noted above.
Here is a photo with the eyebolts and 'L' brackets test fit onto the frame.
Here is a profile view of the vertical frame boards with the hardware attached. The hardware will be removed so that the wood can be fully sealed.
After completing cutting and drilling of the frame boards, the next step was to cut the wings. This involved blowing up the diagram from Camins et. al to 100% scale.
The 100% scale diagram was then cut out to create a template, and the template was traced twice onto a red oak wood plank.
The wings were then cut out using a jig saw.
After cutting, the wings were clamped together and then sanded with a belt sander to get them to an identical size and shape.
Here is a photo of the identically sized and shaped wings after belt sanding.
After belt sanding the wings, the final step was to give each wing a light sand to slightly round the edges and prepare the surfaces for sealing (the label was also removed).
Before sealing, the wings were test fit onto the vertical frame sections. They fit snugly with no movement and will be easily removable via the bolts and wingnuts for transport.
After test fitting, all of the cut, drilled, and sanded boards were prepped for sealing. A water-based spar urethane was used. While spar urethane is plastic based, a waterproof sealer is necessary to protect the wood. We intend to develop a plastic-free trawl (except for the net) that will also require less assembly work this summer as part of our initiative to promote and standardize citizen science studying microplastics.
Here is a photo mid-sealing. At this stage, the short sides, undersides, and holes all have five coats of sealer, and the upward-facing sides are awaiting their fifth coat.
After the final coat of sealer, it was time to assemble the trawl. As noted above, use of the 'L' brackets with bolts and wingnuts will allow for easy assembly/disassembly for transportation. The stainless steel screws for the frame and eyebolts for the tow ropes were glued in with waterproof wood glue.
After assembling the trawl for the first time, it became clear that it would be better to add stainless steel spacers to the holes used to attach the 'L' brackets to the frame and wings. This will allow the bolts to be inserted through the frame and wings more easily without wearing away the sealer inside of the holes. Here is the frame with the 3/4" spacers glued in and sealed:
Here is a picture of one of the wings with the added spacers:
Finally, here is the assembled trawl. It is sitting on packets of two different microns of mesh that we will use to build nets for microplastics sampling. As shown in the diagram from Camins et. al, the nets will be attached to the frame along with a removal collection bag, and we also plan to make the nets removable so that we can test nets of different microns and replace damaged nets when necessary.
The next step is to assemble the nets themselves. Once we have assembled the nets, then we can determine the best means of attachment, which we currently believe will involve using small galvanized or stainless steel clamps. We need for the nets to be easily removable so that we can switch between nets for some of the tests that we want to conduct. We will need to attach a flow meter to the trawl as well.
Once we have completed these additional steps, we will be prepared to begin conducting on-the-water microplastics sampling.
This is a big first step, and we are excited about the progress we have made thus far. While there are still many steps to come, now that we have our first trawl based on a published design, we are prepared to move forward toward sampling, data analysis, and publishing our work--both for the scientific community and for the general public.
Thank you for reading. If you are interested in following along as we continue our efforts to study the scope of the global microplastics problem and contribute to advocacy and potential solutions, please sign up for our email list below.