Bow and stern thrusters can be some of the most demanding systems on any boat’s electrical system, requiring a significant amount of energy the instant they are activated, particularly on/off thrusters. Because of their high amp draw many installers and boat builders choose to have a dedicated battery, or batteries, to power the thruster separate from the house battery bank. The high amp draw of thrusters also means that two of the components of any thruster system on board a boat, the fuse and circuit isolation/battery disconnect switch, are really two of the essential safety devices. Every electric thruster must have a fuse and a way to disconnect it from power via battery switch.
In the case of an amperage spike requiring an abnormal amount of electrical current, the fuse for the thruster system should blow as it is designed to do. However, some situations can occur when the fuse does not blow, making it necessary for the safety of the people on board, the boat itself, and those around to shut down the main power to the thruster using a battery disconnect switch.
The primary drawback to a manual battery disconnect switch is locating and accessing it when you need to shut it off in an emergency. Because the battery switch is installed somewhere in the cable run between the battery and the thruster, it is most commonly located in some sort of mechanical or engine room, or in the bilge near the thruster. That means leaving the helm of the boat to shut it off, which can be dangerous if you are maneuvering in close quarters. It also requires familiarity with the boat to locate it, as someone new to the boat would not necessarily know where to look to find the battery disconnect switch.
Sleipner’s Solution: Automatic Battery Switch
Sleipner has solved the issues with manual battery disconnect switches for thruster systems by offering an automatic main switch which is operated with the control panel for the thruster. That means when you press the two ‘ON’ buttons to turn on your joystick or touch panel, the automatic main switch will turn on as well, powering the whole system. More importantly, it means that when you press ‘OFF’ on the control panel, the whole thruster system will be disconnected from electrical power as the automatic main switch will shut off as well. So in the case of an emergency, you can quickly close the circuit for your thruster system without leaving the helm by simply pushing the 'OFF' button on the control panel, which is an instinctual reaction even for those unfamiliar with the boat and the equipment on board.
Because all of Sleipner’s control panels have an auto-off function that shuts them down after a certain amount of time, the automatic main switch will also shut off when the panel does, meaning the thruster system will be powered down whether you remember to turn it off or not. The automatic main switch also has an emergency manual override so it can be shut down manually as well, though that is rarely needed as the default position of the switch is off so if there is a failure in the switch or control panel the automatic main switch will remain off.
One additional benefit to the automatic main switch is that it simplifies the installation process, as it has a fuseholder for Sleipner’s ANL style fuses for their thrusters. So during installation you only have to fit one item instead of a separate main switch and fuse with interconnecting power cables. The switch also comes with plug-and-play cables to fit with the Sleipner control harness so there’s no need for cutting and crimping the control wires. For all of the safety and convenience reasons laid out in this article, Sleipner always recommends an automatic main switch be installed with all of their thrusters for an optimal, safe, and user-friendly thruster installation. If you have any questions or would like to learn more about Sleipner’s thruster systems, please contact us today and we’ll be happy to help.