NavCalc Dynamic vs Precision Bubble Level

NavCalc is a simple navigation calculator. Given a desired heading, boat speed, and the set and drift of current, NavCalc will display the Course to Steer (CtS) and Speed over Ground (SoG) that will be achieved on that course given the current. NavCalc draws a neat little picture of the heading, current vector, and course to steer on a 360º compass rose which includes both degrees True and Magnetic (if you enter a Magnetic Variation). NavCalc also allows you to enter degrees of leeway and wind direction, and will take leeway into account when calculating the CtS. NavCalc will dynamically update the drawing as you change any of the parameters (heading, boat speed, current set or drift, variation). NavCalc can be used to solve navigation problems like the ones you might find on the tests for Coastal Navigation courses from US Sailing or ASA. It’s also useful for building intuition about how current affects your boat’s course and speed over ground (or velocity made good) since it updates dynamically as you change any parameter.

When your hands are full, your wrist has the answer. PrecisionLevel is a digital spirit level for your iPhone and Apple Watch. Place either device on any surface — within a second, you know whether it's level. No squinting at a tiny bubble in a plastic tube. YOUR WRIST, YOUR LEVEL Hanging a shelf while holding it in place? Leveling a washing machine in a tight space? Glance at your watch instead of reaching for your phone. PrecisionLevel on Apple Watch is a standalone app — no phone required. SUB-DEGREE ACCURACY Hardware accelerometer and gyroscope with Butterworth filtering deliver smooth, precise readings. One-tap calibration compensates for your specific device's sensor quirks. SEE IT AT A GLANCE A responsive liquid bubble shows tilt in every direction. Directional arrows tell you which side is high. Color-coded feedback — green when level, amber when close, red when off. You never have to read a number unless you want to. BUILT FOR THE JOB • Multiple units: degrees, percent grade, mm/m, in/ft • Hold & lock — freeze the reading, then move your device • Dark & light themes — OLED-friendly dark mode or high-contrast light • Configurable decimal precision • Minimal battery usage Free. No ads. No in-app purchases. Ever.