Propeller Calc vs Gobius

This calculator can determine pitch, gear ratio, RPM, propeller slip and speed parameters. Enter any four variables, and it will calculate the fifth. Use the toggle switch to choose which field to calculate. Pitch is the theoretical forward movement for one complete turn of the propeller. Every inch of the boat in contact with the water induces drag. Therefore, the distance travelled differs since the propeller is "slipping" behind the theoretical distance it should travel with each rotation. The difference between theory and reality is called slip. Depending on your application, slip typically ranges between 5% and 20%. A lower number is only sometimes what you are after. Slip of a prop changes with operating conditions and is not a direct measure of efficiency. Please consult professionals for guidance. Happy powerboating

This app is designed to be used with the Gobius C and Gobius Pro sensors. The sensor is measuring sleeplessly from empty to full tank for all kinds of fluids. It gives you to volume in % and liters. 
The sensor is placed direct on top of the tank on plastic and glass fiber tanks. On metal tanks, you need a hole, at least 40 mm.
Gobius C is ready to use; everything is in the box. You get the sensor with a 3M tape, a Quick Guide, 3M tissue, a cable to connect to a power source (12-24 V), and to use for external devices, like warning lights/buzzers, control systems, and analog gauges. The Quick Guide gives you a brief overview of installing the sensor. And the sensor is waterproof IP66. In the app you have everything; Installation Guide with instructions for mounting the sensor on the tank, setup/calculation and displaying the fluid level in different colors. The app has also a Tank Calculator for non-rectangular tanks, such as round and triangular tanks. Installation should take no longer than 15 minutes