CaptainCalc — Offline bridge tools for working mariners
Professional maritime calculator app for Android.
Built for bridge officers, chief officers, ship masters and cadets who need voyage planning, draft survey,
stability calculations, celestial navigation, cargo tools and maritime references in one offline toolkit.
- Built by a former sea captain for real bridge checks.
- Core tools run locally when internet is unreliable.
- Deterministic calculation engine with regression-tested results.
Install from Google Play. The ad-supported Freemium tier keeps essential tools available; Premium removes ads and unlocks the complete professional workspace.
Designed for Real Bridge Work
CaptainCalc was created to support real shipboard operations where accuracy and
reliability matter.
Unlike many maritime apps that rely on simplified formulas or online services,
CaptainCalc uses a deterministic calculation core verified by regression tests and designed to work
completely offline.
It combines navigation, cargo calculations, stability tools, celestial navigation
and regulatory references into a single operational toolkit.
Core Capabilities
Professional Tides & UKC
Signed global FES tide predictions, NOAA high/low-water events, source confidence, point and route UKC, squat and current workflows.
Premium Cloud Backup
Keep up to 10 encrypted restore points for 30 days and restore eligible records on a replacement device with the same Google account.
Voyage Planning
Route planning, waypoint management, ETA calculations, track recording and navigation monitoring tools designed for real bridge workflows.
Draft Survey
Perform draft survey calculations using six-draft method, trim/list corrections and hydrostatic interpolation.
Stability Calculations
Create stability cases, evaluate loading conditions and generate stability reports.
Cargo & Tank Tools
Tank sounding calculations, cargo planning tools and loading advisor utilities for cargo operations.
Celestial Navigation
Almanac-grade celestial calculations including sight reduction, noon sight, star identification and position fixing.
Maritime Regulations
Quick access to COLREG, IALA buoyage systems and maritime reference diagrams.
Navigation Tools
CaptainCalc includes integrated navigation tools for route editing, waypoint
management and voyage monitoring.
Features include:
- route editing
- live track recording
- waypoint arrival detection
- cross-track monitoring
- voyage dashboard
- operational voyage templates
Built for Reliability
CaptainCalc is engineered as a deterministic maritime calculation system.
Key
engineering principles:
- deterministic math core
- golden regression test suite
- validation hardening for operational inputs
- strict input ranges and safety checks
- offline-first architecture
The application does not depend on cloud services for core calculations.
Works Without Internet
CaptainCalc is designed for use at sea where internet connectivity is unreliable
or unavailable.
All core calculations run locally on the device.
Downloaded map packs and operational tools remain available locally. OpenStreetMap-based online tiles may still use internet when no offline pack is installed.
Operational Records and Reports
CaptainCalc can generate operational reports and export calculation
results.
Export options include:
- PDF reports
- CSV data exports
- voyage records
- celestial fix reports
These outputs can be used for documentation or operational reference.
CaptainCalc is designed for professional mariners including:
- bridge officers
- chief officers
- ship masters
- maritime students and cadets
It is suitable for merchant vessels such as container ships, tankers, bulk carriers and general cargo ships.
Currently available for Android. An iOS version is planned once the project reaches its first milestone of professional users.
Subscription:- Freemium is ad-supported and keeps essential calculations available while online.
- Premium removes ads, increases usage limits and unlocks the complete professional suite.
- Premium includes offline access and optional encrypted cloud backup/restore.
- Google Play manages purchase, renewal and cancellation.