Heinrichs Weikamp

Heinrichs Weikamp OSTC 4

The higher-resolution flagship of the open-source OSTC line, with full CCR PO2 monitoring.

Open BLE sync (libdivecomputer)

Syncs wirelessly with third-party apps (Subsurface, Currents, etc.), not just the manufacturer app.

Heinrichs Weikamp OSTC 4
4.2Comparison Score
$900
Released2016
Max depth rating120m
AlgorithmBühlmann ZHL-16C with optional gradient factors
Air integrationnone
Wirelessbluetooth
DisplayHigh-resolution color display
Batteryrechargeable
Digital compassYes
Gas typesair, nitrox, trimix
Gas switches5
CCR capableYes

"Gas switches" is how many different mixes this computer can be programmed to switch between mid-dive, mostly relevant for technical/staged-decompression diving. It doesn't tell you which gas types (air, nitrox, trimix) are supported. See Gas types and the product description above for that.

Pros
  • High-resolution color display, sharper than the OSTC 2/3
  • Full closed-circuit rebreather support with constant PO2 monitoring
  • Open-source firmware with active community development
Cons
  • Price converted from EUR list pricing, may not reflect current US retail
  • 40-hour dive-mode runtime is shorter than AA-battery competitors
  • Niche brand with a smaller dive-shop support network than the majors
Diver community sentiment
Mostly positive

Across Scubaboard and the manufacturer's own forum, experienced and technical divers consistently praise the OSTC 4's large, highly readable display, strong battery life paired with a user-replaceable battery, wireless charging, open-source firmware, and responsive/free customer service even outside warranty. Long-term owners, including a cave diver, report high reliability, and several threads frame it as a legitimate alternative to the Shearwater Perdix at a competitive price. The main recurring complaint is the lack of air integration, plus a sense that the brand is niche with low US availability, and a couple of users mentioned it can feel overcomplicated for casual recreational use.

Scubaboard: OSTC owner discussionScubaboard: OSTC feedback threadScubaboard: Perdix AI vs OSTC 4 comparison

Summarized from public forum discussion (Scubaboard, Reddit, and similar), not a survey we ran ourselves. See the linked threads for the original conversations.

The OSTC 4 is Heinrichs Weikamp’s higher-resolution flagship, built on the same open-source Bühlmann/GF firmware as the rest of the line but adding full CCR constant-PO2 monitoring and a sharper color display for trimix and rebreather divers.