I got the concrete block idea when I was dropping a couple traps near a high traffic area. Bait would be gone, no crabs, and doors left open. Sometimes they took the whole trap. This was back when traps cost fifteen bucks, not thirty five. There were a lot of boats dragging nets thru the area and large barges would come thru and suck unanchored traps out to the channel where they would sink.
I killed two birds with one stone with the concrete block.
If anyone pulls it up near the surface it would coat there boat with six pounds of attached rivermud.
I would never pull it up that far, just far enough to grab the rope
attached to the crabpot. You need a rope long enough that after you drop the block back to the bottom, the trap can be pulled into the boat with room to spare.
I had my traps in five feet of water, so my line to the trap was about fifteen ft. long.
Get rid of the mono line. You dont need it.