TradeSailer project

In this stage of the first iteration we look at the predicted resistance and power under engine or sail.
We start with a prediction of the resistance at any given speed up to hull speed.
To estimate the required axilliary power to make a given speed we look at the shaft line losses, such as propeller, gearbox, shaft seal and bearing resistance to determine the shaft line efficiency.
For this project we found that the resistance increases exponentially nearing hull speed. The proposed electric motors of 160 kW each will give the vessel a speed of 10.25 knots. Reducing this speed to 9 knots halves the required power.
With a 450kWh battery bank a range of 113 nautical miles at 5 knots can be expected. this reduces to about 14 nautical miles at full speed.
After a long search, this segment of the market is not well covered by electric propulsion solutions. Oceanvolt, who are well known in the smaller segment did not have a solution as they only stick to the lower voltage solutions. This was a shame as their servoprop is superb at regeneration.
I found a company called Stok Electric who are busy to develop a solution which should be available on the market by 2025. They have been very helpful in providing preliminary information.
The power under sail is determined by a Velocity Prediction Program and the generated results, based on preliminary assumptions, shows no surprises. The vessel will be able to reach it’s hull speed of 11 knots with a true wind speed of 20 knots on the beam.