Nautical Unit Converter
Convert between nautical miles, statute miles, kilometres, fathoms, metres, and cable lengths. Includes speed conversions for knots.
Your tools stop working when the Wi-Fi does
The Sailor's Knife is the answer
Field work. Remote locations. Unreliable connections. Air-gapped environments. Cloud tools become expensive paperweights. Every tool works offline, forever. Open the HTML file, do your work. No login, no sync, no server required.
The Sailor's Knife is a single-file knife with 8 tools that runs entirely in your browser. The Sailor's Knife v2.0 gives mariners eight practical tools and an emergency system in a single HTML file. Convert nautical units, reference the Beaufort wind scale with sea state descriptions, calculate tide heights using the rule of twelfths, compute compass corrections for variation and deviation, browse knot guides by category, reference IALA Region A and B buoyage systems, plot dead reckoning legs with leeway and tidal set on a dynamic chart, and check sunrise, sunset, twilight times, and moon phase for any date and position. The MOB button instantly logs your position and starts a timer. Everything works completely offline — perfect for passages, anchorages, and ocean crossings.
WHAT'S INSIDE
8 tools in a single HTML file
Beaufort Scale Reference
Complete Beaufort wind scale from 0 to 12 with wind speed ranges, sea state descriptions, wave heights, and land condition indicators.
Tide Calculator
Estimate tide heights between high and low water using the rule of twelfths. Enter known tide times and heights for your port.
Compass Deviation Calculator
Apply variation and deviation corrections to convert between true, magnetic, and compass bearings. Includes the TVMDC mnemonic.
HOW IT WORKS
Three steps. No setup.
1
Download the file
Purchase The Sailor's Knife and download a single HTML file. No installer, no account, no setup.
2
Open in any browser
Double-click to open in Chrome, Firefox, Safari, or Edge. Works on any operating system.
3
Start working
Your data stays in your browser's local storage. Nothing is uploaded. Ever.
COMPLIANCE & GEOGRAPHY
Global
Works in any country. No server dependency, no regional restrictions.
FAQ
Frequently Asked Questions
How does The Sailor's Knife solve the working without internet problem?
The Sailor's Knife runs entirely in your browser. Field work. Remote locations. Unreliable connections. Air-gapped environments. Cloud tools become expensive paperweights. Every tool works offline, forever. Open the HTML file, do your work. No login, no sync, no server required. Nautical unit converter, Beaufort scale, tide calculator, compass deviation, knot reference, buoyage systems, dead reckoning plotter, and celestial almanac — plus a Man Overboard emergency button. Your chart table in a file.
Is my data safe with The Sailor's Knife?
Yes. The Sailor's Knife is a single HTML file. It never connects to any server. Your data stays in your browser's local storage on your device.
What makes The Sailor's Knife different from cloud tools?
Cloud tools require internet, charge subscriptions, and store your data externally. The Sailor's Knife is a one-time purchase ($39), works offline, and never transmits data.
Is The Sailor's Knife really just one file?
Yes. The Sailor's Knife is a single HTML file containing 8 tools. Download it, open it in any browser, and start working. No installation, no dependencies, no accounts.
No cloud One fileOne-time purchase
Get The Sailor's Knife — $39Sovereignty as a Service