Sounding work requires a vessel speed of 5-6 knots for a long time while maintaining an accurate heading to minimize the number of passes. Using a powerful diesel engine at low speeds for a long time will lead to increased vibration, wear of some components due to lower speeds, and relatively increased fuel consumption due to the need, in addition to useful work for the movement of the vessel, to also spend work on rotating the masses of mechanisms in a powerful diesel engine. If you use two stationary engines for movement, and only one engine is turned on for sounding, then it will be difficult to keep the boat on course due to the reactive torque of the propeller and the need to keep the rudder slightly shifted to one side. This will increase driving resistance and increase fuel consumption.
The proposed 12-meter aluminum boat of the BSY-40 “Dolphin” project for surveying work involves the use of two propulsion schemes:
- one diesel engine with shaft and propeller for cruising speed over 15 knots
- two electric outboard engines.
The use of two propulsion systems has a number of advantages:
One main engine will be used to propel the boat during transitions to measurement points. From the moment the measurement site is reached, the main engine is switched off and all maneuvers are performed by electric motors.
This increases the service life of the main engine, and also results in significant fuel savings.
To move the boat in measurement mode, it is proposed to use low-power outboard electric motors, which will receive energy from Li-Po batteries, which, in turn, will be charged through chargers from a diesel generator. The power of the diesel generator can be within 15-20 kW. The estimated battery capacity could be 5-10 kWh. Voltage 48V. It is proposed to use solar panels with a power of 1-1.5 kW on the boat, which will additionally save diesel fuel when moving during measuring work. Modern electric motors are simpler in design than internal combustion engines, do not have a brush mechanism, and have high torque from zero speed.
Advantages of using electric propulsion:
- high controllability at low speeds due to variable thrust vectoring;
- high energy efficiency due to the use of a low-power diesel generator;
- additional recharge of batteries from solar panels;
- low vibration and noise;
- high directional stability;
- high protection from old nets, algae and other underwater obstacles (during measuring work, the outboard engine can be raised and easily cleared of algae, nets, etc.);
- at high speeds, the outboard engines are raised and do not create additional resistance to movement.