This is what all the lobster boats use today. The rope goes in between those two discs and the pressure as it goes into the groove created between the discs holds it in place. That is the way the traps get hauled up from the bottom of the ocean floor.
The thinking behind the new experimental hauling plates is that they will have less friction on the rope to make the rope last longer. The rope that the lobstermen use is a by-product of oil and it’s cost has gone way up with everything else. By using the new plates they hope they will get a longer life out of the rope and reduce costs.