A side project, not the day job
Bits We've Built
Small diving tools we make for our own amusement, shared here in case anyone else enjoys them.
For education and fun only. Everything on this page is built for learning and entertainment. None of it is a substitute for formal dive training, certification or the manuals and courses provided by equipment manufacturers. These tools do not plan decompression, they are not dive computers, and they must never be your only source of dive planning. Cross-check every number, dive within the limits of your own training and certification, and if a tool and your training ever disagree, follow your training.
Each one started with someone in the troop wanting a tool that didn't exist, and building it between dives.
JJ-CCR HUD Trainer
A familiarisation aid for the JJ-CCR head-up display, which reports ppO₂ through blink patterns: three columns of LEDs, one per oxygen sensor, four rows, and a blink cycle every five seconds. Which LED blinks tells you the range, and how many times it blinks tells you how far you are from 1.0.
It's a bit of fun for getting familiar with the patterns on dry land. It is not rebreather training and it is not a substitute for the manufacturer's manual or a proper CCR course - if you're diving a JJ-CCR, the manual and your instructor are the only authorities that count.
- Simulator - a live, driveable HUD. Watch the blink patterns until colours and counts become numbers without you having to think about it.
- Signals - the displays beyond ppO₂: start-up self-test, command entry, calibration, alarms and error codes, each one animated.
- Quiz - twelve questions mixing "what is the ppO₂?", "is it safe?" and "what is the HUD telling you?" to see how much has stuck.
In the members area
Dive Planner
Open circuit and JJ-CCR. ppO₂/ppN₂ tables, MOD, best mix, EAD/END, CNS and OTU tracking, gas planning with minimum gas and turn pressure. CCR mode models a constant setpoint loop and treats the bailout MOD as the hard depth limit.
No-stop times
Computed with Bühlmann ZH-L16C using verified coefficients and a configurable surfacing gradient factor. Checked against published figures by its own test suite.
Dive Log
Location, date, gas mix, depth, time, conditions, deco, buddy, rating, notes and photos. A logged dive can point back at the plan it came from and keeps a copy of it even if that plan is deleted.
Kit Register
Your gear by category with purchase and service dates. Anything overdue - or due within thirty days - gets badged, and you get a kit-check nudge when you sign in.
How we build it
Small, fast and private. The members area sits behind Microsoft Entra sign-in and is invite only. Your dive log is yours: every record is stored against your own account and no member can read another member's data. Photos are held privately and only ever served back to you.
Worth repeating. These are hobby tools for education and fun. The planner produces estimates from simplified models, does not generate decompression schedules, and is not a dive computer. Nothing here replaces formal training, certification, dive tables or the manuals for your own equipment. Cross-check every number and dive within the limits of your training.
Got an idea for a tool?
Most of what we've built came from someone moaning about a problem on a surface interval. If there's something you keep wishing existed, tell us - no promises, it's a hobby.