A dive log book helps you remember more than where you entered the water. It can preserve the conditions you encountered, the equipment you used and the small observations that make the next conversation with a buddy or support technician more useful. For tankless divers, a few extra fields make that record particularly practical.
You can use a notebook, a spreadsheet or an app. The useful part is consistency: write the same core details after every outing while the experience is fresh. This is a record of what happened, not a substitute for training, a dive computer or the planning procedures you learned.
Start with the place and conditions
Record the date, site name, entry and exit points, and the people who joined you. Describe visibility and surface conditions in plain language. If you did not measure something, say so. “Estimated visibility” is more useful than a precise-looking number you cannot support.
Add a short note about access, such as where permission came from or which operator provided the briefing. Record any restrictions that affected your visit and the source you checked. Rules and access can change; a note from a previous trip is a reminder to verify them again, not permanent permission.
Describe the equipment configuration
Write down the model and the actual battery configuration. “BLU3” alone is not enough to distinguish a Nomad from a Nomad Mini. Include accessories that changed the setup, such as a reserve air supply, camera or detector.
Record your own system identifier if you use more than one unit, but keep serial numbers out of public posts. Note any equipment concern factually: what you observed, when it occurred and what you did afterward. Do not diagnose an internal fault from a log entry. If a concern could affect operation, follow the manual and contact BLU3 Support.
Keep runtime observations in context
A useful battery note includes the pack used, its indicated charge before the outing and the duration you actually recorded. Note whether the outing ended by choice or because you followed a training procedure related to battery status. Avoid converting one good experience into an expected runtime for future dives.
BLU3 lists typical standard-battery runtime of 45–60 minutes for Nomad and 35–40 minutes for Nomad Mini. Actual runtime varies with depth and breathing rate. Your log can help describe your experience, but it cannot guarantee remaining air delivery or justify extending a dive beyond your plan.
Use this copyable entry
- Date and site: Name, general location and entry/exit description.
- People and briefing: Buddy or team, operator and relevant site instructions.
- Conditions: Visibility, surface observations and anything that changed.
- Equipment: System model, battery configuration and accessories.
- Dive record: Times, depth and other information from your instruments and training.
- Battery observation: Starting indication, recorded use and context.
- What I noticed: Marine life, photographs, equipment observations or tasks completed.
- Follow-up: A question for an instructor, support request or a change to the next trip’s preparation.
Turn observations into useful follow-up
After several outings, review the notes for questions rather than trying to calculate performance promises. Perhaps a mask adjustment interrupted several visits, or the same accessory was repeatedly missing from your bag. Those patterns can guide a discussion with your instructor or improve your packing routine.
For equipment support, separate an observation from an assumption. “The unit made a different sound before entry” is a clearer starting point than “the pump failed.” Include the model and circumstances when contacting support, and follow their directions about what information to provide. A complete log reduces the need to reconstruct events days later.
Protect the details you share
A personal log may contain names, photographs and locations that other people do not want public. Keep a private full version and share a shorter version when posting online. Avoid disclosing sensitive wildlife locations or implying that a recorded visit grants others access.
Before any new dive, use the current owner’s manual, Fitness to Dive Evaluation and BLU3 training. A well-kept log gives you a clearer memory of the last outing. Good preparation determines what you do on the next one.