Batteries, tanks and engines
Most sailors are well accustomed to the navigational data available from their instruments. But recent developments have produced devices capable of generating a lot of data relating to critical onboard systems, including batteries, tanks and engines. Imagine early warning of the engine overheating, water in the bilge rising or knowing exactly how much fuel is left, visible on your instruments? This information could make the difference between calling out the lifeboat and making it safely home.
Bigger or more modern engines already produce digital data, which they typically share with the engine display panel. Volvo Penta’s entire range even includes an N2K output, ready for hooking up to your instrument network. But even a relatively simple engine like the Beta Marine 30 in my Sadler can be tapped for data. As it is, the engine senses coolant temperature, oil pressure and revs which it displays on the tachometer, and in the form of alarms that are triggered when pressure drops or temperatures rise.
By replacing these simple on-off sensors with a resistive type sensor, it is possible to constantly measure these engine parameters. Your engine manufacturer or dealer will be able to recommend sensors compatible with your specific model.
The challenge then is to turn the electrical signals from the senders into NMEA data. For this, you need a special unit such as Actisense’s EMU (£387.61) or the Alba-combi (€399). Because they are designed to accept inputs from commonly used marine senders, there is little programming required. You just need to connect up the wires from the oil and temperature sensors to the resistive inputs, then plug the other end of the unit into your N2K network.
As with previous scenarios, this network could be a new MFD or cockpit display, or it could be simple — just power, the engine monitor unit and then a NMEA Wifi gateway to get the data onto a phone (more below).
Another option would be to install a dedicated Veethree display for engine data (£1,019.70). This unit has a harness on the back that you connect up to the sender wires for older non-electronic engines, or to the J1939 CAN bus for newer engines. With its N2K output, this device serves the double purpose of displaying your engine and tank data, then sharing it around the network.
Tank sensors work in much the same way as the engine senders. If you have existing sensors, they are likely to be resistive types which can simply be wired up to the resistance terminals on your EMU or Alba Combi, although you will have to connect a laptop to the EMU in order to calibrate for your tank. An alternative option is to use a specialist N2K tank adapter that allows you to plug your tank sensor directly into the N2K network. Maretron offers one for a fairly steep £295. Yacht Devices charges £128 for its YDTA which will work with standard N2K fittings and with Raymarine’s Seatalkng.
Maretron also offers an N2K monitor (£310) which can be used to show bilge pump use and could provide warning of a leak. And Yacht Devices offers a range of handy N2K modules which simply plug into your network. These include a digital barometer, humidity sensor and thermometer, as well as an exhaust temperature sensor (£125) that can measure up to 8000 C.