Engine Instrumentation

When Fir last sailed, the helm could only see the compass and two pressure gauges. Both gauges read air pressure in the operating system for the engine telegraph. More familiar devices with alarms and the ability to measure specifics such as RPM, temperature, and oil pressure were not included in the Wheelhouse. Instead, FIR operated with a team of engineers to monitor, read, and report all activity in the Engine Room. The Engine Room would communicate to the Wheelhouse by ship telephone and a few manual signal lights.

Part of modernizing FIR is reducing crew count by updating equipment so that Engine Room data is always available to the Wheelhouse. Based on the reviews from Panbo, we decided to build our system around the EMU-1 from Actisense (about $430). There are several options for analog to NMEA 2000 converters. The EMU-1 seems to have more adaptable programming which is likely to be a big advantage for our application.

Stock photograph of the EMU-1

Stock photograph of the EMU-1

The EMU-1 will convert data from 6 analog sending units, 4 alarm switches, and an inductive tachometer into a digital signal. The digital signal is converted to NMEA 2000 CANBUS sentences which are carried by the network. As a result, the information is available at several display units throughout the boat as well as smartphones.

The EMU-1 can work with most sending units. The configuration software has profiles for sending units from most major manufacturers which will simplify the install. We selected VDO senders (between $20 and $40 each). Typically, the electrical ground for a sending unit is the engine block — so there is only one wire from the sender to the EMU-1, sharing the same ground. We are using “floating ground” or “isolated ground” senders requiring a separate ground wire since we are trying to lay new over existing systems. In a floating ground system, the sending unit requires two wires. The DC negative from the power supply passes through the sending unit then to the signal post of the EMU-1.

The new system will include, a 12VDC power supply (about $20) powered from the 110VAC circuit, the EMU-1, and the sending units.

One goal of the next work period is to build a test system where we connect the power, sending units and NMEA 2000 backbone to the EMU-1. This will test our network connectivity between the Wheelhouse and the Engine Room. It will also allow us to configure the EMU-1 to read the sending units that we selected. We expect to be able to set up all the standard gauges and alarms. Fir, however, has some rather atypical gauge requirements such as “reduction gear lube oil temperature". It will be interesting to see how well the EMU-1 and NMEA 2000 protocols will adapt to Fir.