1/2" poly rope clamp

Hi,
I went out today with my new snoodless trotline and new propstick. My new setup, made possible by researching and asking questions here, with 1 1/2 " PVC was far better than my other setup, which was a tar coated twisted line and a little bitty propstick made from 3/4" pvc. I had a few hicups but am encouraged. One problem I had was that I set up too close to a creek that has a marina, on july 4th, bad move. Well one of the many sailboats came by and snagged my control line and dragged the 40 lb weight, a litter bucket 1/2 full w/ concrete and an eye bolt, until the rope came free. What gave was the rope clamp that was the type as seen in the attachment. I also used the a thimble inside the loop. Luckily I listened to you more experienced members and used poly so the line floated. So i got the rope tied to the bouy on and set out to try again. As i was making the run I noticed that most of my bait was missing, I used chicken necks and a slipknot in #5 locktite, The force of the boat pulling the line popped the bait right off. Then I get to the end and the control line is gone again. This time we find the line floating about 50' away and nothing attached so I lost the weight. So my question is what do you use to secure/tie poly rope? As you know tying a knot in poly is not an option.

Thanks,
Tim