When converting an existing boat to electric drive, it is best to measure the drag of the hull by carrying out tow tests. These tests enable a curve to be plotted showing the power required for a given speed. From these measurements, the operating speed can be chosen to give good energy efficiency. This will rise rapidly as the hull speed is approached. Power consumption can increase 4 or 5 times without much increase in speed, the extra power going largely into wave making.
Larger propellers attain higher efficiency in transmission of the drive.
It is important to match the propeller to the drive with as low a loss due to slip as possible. Accurate measurements enable components to be sized economically. Error in sizing, say, the batteries could prove quite expensive. The experience we have gained in many marine installations is available to installers and D.I.Y. customers. In particular we can help with system design and with meeting safety requirements on such aspects as timer-controlled battery ventilation.