How to Build a Public Safety Diver Entanglement Box for ERDI Training
Brent Clevenger Aug 12, 2026
Public safety divers don’t get to choose their conditions. Submerged vehicles, missing-person recovery, crime-scene evidence — visibility is often zero, the water is contaminated, and the threat of entanglement is real. The best way to prepare for that is to train for it in a controlled environment.
At Sink or Swim Scuba, we built a Public Safety Diver Entanglement Box so ERDI divers can practice controlled escapes from entrapment, sharpen their cutting technique, and build the composure to respond under stress. This guide covers how to build one, how to use it in training, and why it belongs in every PSD team’s toolkit.
Contact us to schedule ERDI team training → or call 704-823-0501.
What is an entanglement box?
The entanglement box is a modular PVC frame filled with realistic underwater hazards — netting, fishing line, rope, wire, cables, and hose. It simulates the debris and snag points public safety divers face on real missions, especially around docks, submerged vehicles, boat lifts, and overgrown ponds or retention basins.
The diver enters while tethered and must:
- Maintain composure
- Manage line tension
- Use a cutting tool properly
- Communicate with the tender
- Escape safely while conserving air
Training objectives
The box reinforces the skills that keep divers alive when things go wrong:
- Tether awareness and topside communication
- Effective cutting-tool handling
- Controlled breathing under stress
- Zero-visibility decision-making
- Diver rescue readiness
We build this exercise into our ERDI public safety diving courses, but it also works well for in-service team refreshers and scenario-based qualifications.
Build guide: materials list
Everything is available at Home Depot, Amazon, or your local hardware store.
Frame:
- (6) 10-ft lengths of 1.5-inch Schedule 40 PVC pipe
- (8) 1.5-inch PVC 90-degree elbows
- (4) 1.5-inch PVC T-connectors
- (1) 16 oz. can PVC cement (optional — only if you want it semi-permanent)
- PVC saw or cutter
Entanglement materials (choose your mix):
- Nylon cargo netting
- Old fishing net or seine net
- Polypropylene rope (various sizes)
- Baling wire or safety wire
- Paracord
- Garden hose or electrical cord
- Zip ties to attach materials to the frame
Optional add-ons:
- LED dive lights to simulate vehicle lights
- Dummy regulator or mask to simulate snag points
- Waterproof ID tags for timed runs
Assembly instructions
- Build a rectangular frame roughly 6 ft long × 4 ft wide × 4 ft tall using the PVC and connectors.
- Use elbows for the corners and T-fittings for reinforcement.
- Cement it if you want it permanent, or leave it dry-fit so it breaks down for transport.
- Wrap cargo netting around the inside surfaces, leaving a clear diver entry point.
- Zip-tie or loosely hang rope, fishing line, and cables throughout the interior.
- (Optional) Create dedicated entanglement zones by hanging loops or twisting line near face level.
How to use it in training
- Tender briefing. The topside tender explains the objectives and maintains communication.
- Diver entry. The diver enters blindfolded or in a blackout mask.
- Timed escape. The diver performs calm navigation, deploys their cutting tool, and self-extricates.
- Rescue scenario. A standby or second diver deploys if the primary simulates loss of control.
This isn’t just a confidence builder — it’s a lifesaving skill set reinforced in a controlled environment.
Your gear has to work when it counts
Entanglement drills are hard on equipment, and a cutting tool or regulator that fails mid-scenario defeats the purpose. Public safety gear is life-support equipment — it deserves real, factory-level service. We’re a factory-authorized service center for Interspiro and OTS and we service PSD regulators, full-face masks, and communications, with every regulator bench-tested to manufacturer spec.
Learn more about our scuba equipment repair and mail-in service, or ask us to look over your team’s kit before your next training cycle.
Make it part of your ERDI program
We include entanglement drills in our public safety diving programs for teams across North Carolina, South Carolina, and the East Coast. If your dive team would benefit from hands-on entrapment drills, gear familiarization, and drysuit or full-face-mask integration, we can build a program around your agency’s needs — from ERDI awareness through technician-level training.
Visit us in Gastonia, NC · Call 704-823-0501 · Email Dive@SinkorSwimScuba.com
