When its deployed to catch a crab, does the upper ring float a few inches above the lower ring and the crab comes in between the two rings to feed, and then when its pulled by the crabber the lower ring is pulled up and catches the crab in between the two rings?
It takes me awhile just to be able to buy them for myself, that's why I want to experiment with making them, both rings are sealed, there are no holes. The are also good at being tossed as Frisbee to be repositioned 10 to 20 feet
So from a little research and guessing I'm going to say it's 5/8" OD, 1/2" ID polyethylene tubing, connected using a section of 1/2" pvc, which has an ID of just less then 5/8". Weight in bottom one doesn't matter much, maybe sand would be cheapest. Netting could be anything but I found decorative fish net on amazon that feels,smells like used fish net. Smaller mesh then pictured but should work. I'll have a prototype with this stuff later tonight.
Would you be willing to provide diameter of the hoops? And what do you pay for them? costs of these parts is not super cheap, so it may not be worth making them if you can buy them for similar cost. I will provide breakdown of costs later.
For 2 ft diameter traps, that's 12.5 ft tubing per trap (two hoops) about ~5$ per, plus netting which was $16 per 5x10 ft section, about 8 ft2 per trap, or ~3$ of net. So $8+ per trap, plus little pieces.
Also, i just test fit, and the tubing/pvc sizes above fit great, very snug, seem to make an air/water tight connection and study enough for the application, will know more after final constructuon.
Wow I didn't realize people here were hard at work putting prototypes together, I would be happy to go over one with anyone truly interested in how they work, just pm me, I'm out of pasadena. I was getting them for 14 a piece but the guy is 90 and I haven't been able to get ahold of him, I hope he is ok
I have 6 netted hoops put together. From the pics it looks like beads are used in the closure mechanism, as of now without beads, juts rope, I'm not sure I'm happy with the closing, and I went with 18" diameter to squeeze and extra trap out of my 25ft, they may be a bit small. If you could post/pm pics of the bead part and how the rope is woven to make it close that would help. Also outside diameter of the two hoops and your thoughts on if it's a good size.
I'm an engineer and I think I enjoy the tinkering parts of hobbies more then the activities sometimes. This looked like a good project. Will post details once it's all figured out. But I'll say, at $14 per, if your time is worth anything you might just want to buy a bunch if you get the chance agian.
Ok so here is a little help on the measurements. The diameter of the weighted hoop is 16 1/4 to the outside while the floating hoop is 14 3/4 to the outside. It's made so the upper hoop falls into the lower hoop when pulled up. I have caught 2 crabs per trap before. With the bead mechanism there are 3 lines that attach the 2 hoops with 2 beads on each line. The top bead is just a stop point for the top hoop so it doesn't continue to float up where as the bottom bead is tied to the top hoop so the line can pass through to be tied to the bottom hoop.