Boater’s Tool Bench
Free, fast, ad-free marine calculators. Bookmark this page — every tool runs entirely in your browser, works offline, and never sends your data anywhere.
Anchor Scope Calculator
Calculate the correct rode length for your anchoring depth, tide range, and conditions. Includes storm-mode 10:1 and Bahamian moor guidance.
Open toolFuel Range Calculator
Estimate your boat's cruising range, endurance, and fuel burn based on tank capacity, cruise speed, and GPH. Plan trips with a safety reserve.
Open toolSpeed / Time / Distance
Solve the classic navigation triangle — given any two of speed, time, or distance, calculate the third. Includes ETA and waypoint planning.
Open toolMarine Battery Sizing
Size your house bank for overnight anchor loads, calculate lithium vs. lead-acid runtime, and estimate recharge time from alternator or solar.
Open toolAbout These Tools
Every calculator on this page was built and validated by our team of USCG-licensed captains. The math comes from the same formulas we use on the water — there are no shortcuts, no “close enough” approximations, and no sponsored placements. If a calculator gives you a number, you can trust it on your boat.
All tools run client-side in your browser. No data is sent to any server. You can use them offline — save this page to your home screen on your phone and it works without a cell signal, which is exactly when you need it most.
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