The Status Quo is a 45 foot Salmon trawler built in the Puget Sound for the 2011 Bristol Bay Sockeye Season.  The special requirements for this competitive fishery is a light boat with only a 21” draft to allow operation in six feet of water.  The vessel is being powered by a single mechanical diesel engine which delivers up to 800 HP using twin turbo chargers.  Since this was a “ground – up” project, instrumentation needs could be carefully considered during fabrication.  Being, a “work boat” instrumentation needed to practical, reliable, and functional.

The owner decided to go with a SeaGauge G32N display panel mounted in a custom aluminum case with a RAM bracket to allow adjustment of viewing angle. The SeaGauge Remote Sensor Unit and SeaSwitch Module were selected to feed engine and vessel information to the high-brite touch screen display.  The high-performance engine came with senders installed for Engine Water Temp, Oil Pressure, Dual Turbo Boost, Transmission Temperature, and Transmission Pressure. The owner chose to add twin EGT (pryo), battery bank voltage, and dual fuel tanks to the package.  Tachometer readings were to come from a inductive pickup installed in the bell housing.  The SeaGauge Remote Sensor Interface Unit would be installed near the engine and a single serial (RS232) cable run up to helm station to attach to the display.

The Status Quo's Engine and Guts

With the vessel under construction, the engine was freely accessible in the warehouse and could be pre-wired while fabrication of the hull continued.  The engine manufacture had provided schematics for the dual 16-pin connector harness that provided access to the senders. Being a mechanical engine (for reliability), there were no other electronics available for performance monitoring, so Chetco Digital implemented a complete SeaGauge system. 

The initial challenge was analyzing the schematics to determine what functions were available and how to wire up to the dual connectors. The schematics reveled that the dual connectors were actually for twin gauge panels with dual senders for Engine Tem, Oil Pressure, and Boost already installed on the engine.  Due to the size of the vessel and location of the engine mid-ship near the helm, the owner opted to go with a single instrument panel and thus leave the other connector unused.

The preinstalled 16-pin sensor harness made it possible to prewire the engine senders to the SeaGauge Remote Sensor Unit out of the vessel. The twist-lock connector would allow the entire harness and sensor unit to be removed when final engine mounting was preformed.

Since this was a unknown engine package, it made a perfect application for the versatile SeaGauge system.  Ohm meter tests of the temperature senders showed them to be standard VDO 250F resistive senders.  Markings stamped on the Boost Senders were VDO 80 PSI and oil was VDO 150 PSI.  The temperature sender for the Transmission was a VDO 400 F Transmission pressure.  The only issue was the 400 PSI sender for transmission pressure which used a reversed resistance curve of 240 ohm (0 PSI) and 10 ohm (400 PSI).  This could be corrected by loading a inverted calibration table. The EGT probes were going to be K-Type thermocouples so the SeaGauge unit was ordered with the dual amplifiers so they could be directly wired to the internal terminal posts. Voltage monitoring would be performed by connecting a lead from the 12V and 24V battery banks. The two fuel tanks used a standard resistive float arm sender (30 – 180 OHM).

Status Quo Fuel Tank

The wires from each sender on the engine were traced back to the connector with a ohm meter and verified with the schematic.  In all, only 7 of the 16 pins (Eng Temp, Oil PSI, P BOOST, S BOOST, TRAN Temp, TRAN PSI) were needed for the senders as the other pins were for optional alarms. Direct connection to the additional external senders (P EGT, S EGT, P FUEL, S FUEL, 12V Battery, 24V Battery, Tach+, Tach-) rounded out the SeaGauge Remote Sensor Unit's harness.

Once the senders were all identified and located, the 12ft cable harness could be built by solder of the seven 18 gauge wires to the mating 16 – pin engine connector and then the remaining 10 left as labeled flying leads.

The SeaGauge G32N display head was configured with a new “Garmin Look” theme in Chetco's vDash Software, including needle dials for Tachometer, Engine Temp, Oil PSI, Tran Temp, Tran PSI, with the remaining dials as Digital Readouts for the various sender values.  Control of the 12 relays on the SeaSwitch module were accomplished via the separate SeaSwitch page activated by touch from the upper Right Corner.  Dimming for Night Mode viewing is accessed from the main menu page in the lower left hand corner.  The vessel owner was able to view all the display configurations on the bench with only a 12V supply in addition to any adjustments made by the vDash application running on a Windows based PC attached via USB cable.

One of the Status Quo's Custom Gauge Screens via Chetco's vDash Software Application

The sensor wires were attached to terminal posts on the SeaGauge Remote Sensor Unit after passing through three cable glands. Cable entry through the gromments was difficult due to the thick insulation on the wire and could have been a simpler process with thinner wiring.  After final assembly, the connector was plugged into the engine and the power and ground connected to a 12V battery.  Everything powered up and the temperature senders gave the correct reading of the engine block on the garage floor (45 degrees).  All pressures showed 0 except for the transmission which was maxed out at 400 as predicted by the inverted table.  Taking a short wire to ground forced the send to zero so it was working correctly and simply needed new tables loaded.

At this point, the instrumentation panel has been staged and is ready for installation once the engine is installed into the vessel.  Open action items include programming of transmission pressure calibrations and creating a new theme file for separate Night Mode graphics.  Future Blog entries hope to cover the final installation and tachometer calibrations once the vessel is in the water.

Joe Burke
Chief Technology Officer
Chetco Digital Instruments, Inc.

Joe programming a SeaGauge Sensor Interface Unit