MercMon Must Go

Note: 27JUL13 update,
see removal of this stupid MercMon gauge at: July 27, 2013: Supply Run

Loyal readers here have likely picked-up on two common-traits of the captain of the Rose: one, he’s not afraid to try new technology and two, his efforts don’t always go as planned.  Another thing loyal readers might remember is the captain wasn’t totally thrilled with initial testing of the Mercury SmartCraft MercMon monitor (see the initial installation  smartcraft-mercmonitor-a-critical-review); that opinion hasn’t changed through use.

To be fair, some of the things this monitor does is pretty cool.  But to be totally accurate, it is the gateway features of the MercMon that are impressive… unfortunately in this writer’s opinion, everything about the gauge part of the MercMon is sadly ineffective (or dangerous).

After several months of actual use, the luster of the MercMonitor has worn-off.  This post is offered for those people contemplating buying or installing a similar system, as a means to inform, for them to make their own decisions.  Here’s the details:

The SmartCraft MercMon:

The MercMon

The Mercury MercMon Monitor (V6.0)

  • 8M0048274 is the base-model (79-8M0062374), offering only 9 single-engine gateway outputs
  • 8M0048275 is the 1-engine RPM Smart Tow (79-8M0062375), offering 20 gateway outputs, plus troll-control and SmartTow (DTS-only for wakeboard/waterski launch)
  • 8M0048276 is the multiple (4) engine SmartTow Pro (79-8M0063240) with 25 gateway outputs and troll-control, SmartTow, plus comes with a GPS-puck
  • 8M0048277 is the multiple (4) engine Gateway Premier with 25 gateway outputs, plus troll-control, plus SmartTow launch-control*
    * I ordered/tested 79-8M0063241, which is the newer part# for 8M0048277, even though the Christina Rose doesn’t have DTS (digital throttles and shifts)

The Good:

  • The gateway-function, which translates Mercury’s SmartCraft data to the NMEA-2000 network is exactly what the Christina Rose needed.  The ability to see technical-information about the engines, position, and sonar on the Rose’s crisp Garmin (GPSMAP 5208) display is critically important

The Bad:

  • Almost everything else
  • Although the MercMon has gateway-information for both engines present, which proves this one gauge is communicating with two engine ECMs just fine, for some reason Mercury chooses to make the very first power-up option of the MercMon be selection of WHICH ENGINE it would display data on the gauge.  The gauge will not allow you to flip to display information for the other engine without resetting everything (which blanks-out all configuration and defaults, including any custom dual or triple displays).  I can only assume this is to sell more gauges.
  • Engine-Synch is not an available display-screen, even though the manual discusses it as a valid option.  The manual was read in entirety before purchase, as RPM-Synch is the #1-used function of the original SmartCraft center-gauge.  Interestingly, this is the only screen that does not come up as described in the manual, and as stated before: it’s the #1-used function on the Rose and the monitor obviously reads both engine’s ECM (and displays RPMs for both engines on the Garmin’s NMEA-2000).
  • Buttons, buttons, buttons.  It is ridiculous how many buttons you have to press to configure the gauge to show what YOU want it to display (and gawd-forbid you reset the MercMon after spending hours configuring the displays).  It is also equally miserable to try to configure anything new (or flip between saved displays) when underway.  The Christina Rose is a very smooth cruiser, but it is difficult and VERY time-consuming operating the gauge while underway, akin to texting on a cell-phone while driving a car.  And, what’s worse is the button-operations aren’t really intuitive, you need the manual with you because certain operations are accessed only through other options that aren’t necessarily even associated with that function.
  • ECO mode, which is how Mercury touted this as a revolutionary product, has no benefit on the Christina Rose, because she doesn’t have digital-throttles or electronically-adjustable trim or tabs.  Nonetheless, ECO-mode does not display any information that wasn’t already available by monitoring fuel-economy, which is an original function of the SmartCraft (not the MercMon).  Anyone with a functioning brain can figure out the boat’s sweet-spot by simply monitoring fuel-economy.  What is sad is, the original SmartCraft gauge (replaced by this MercMon) displayed fuel-economy for BOTH engines, this ECO-gauge only displays economy for the engine selected at the first installation screen.
    Another nighttime cruise

    Loyal readers may remember this other nighttime cruise photo, showing the unreadability of the SmartCraft MercMon (center), which was optimized for brightness and contrast as much as possible

  • The display screen was not well thought out, at all.  The Rose’s captain has been an Electrical Design Engineer for almost 25-years, so he gets-it.  He understands the trade-offs in displays, LCD versus LED versus EL versus Paperwhite… unfortunately this gauge’s display seems to be chosen by a bean-counter for cost rather than performance for the user.  The screen is mostly readable during daylight-hours, but is pathetic and approaching dangerous at night.  The back-lighting is overpowering at night, whether in daytime or nighttime display mode, and it’s not a matter of just brightness… it’s a matter of contrast too. The required brightness-setting is obviously a function of outside conditions… daytime requires a higher brightness than night. For those who enjoy cruising at dusk, the brightness AND CONTRAST settings of this MercMonitor have to be constantly-manipulated during the daylight-transition, a process that is seriously 20-button pushes during a time the captain should be paying attention to things like channel-markers, boats, skiers, etc.   This gauge is unreadable while underway at night, and is so bright as to destroy night-vision at any brightness setting over 0%.  The captain can read his Timex at night while underway, not this MercMon.

Part of the reason for this near-hostile summary of the Mercury MercMon gauge comes not-only after months of operation, but ultimately due to Christina’s last nighttime cruise (see oct-06-2012-a-cruise-for-supper).  Returning to port, over 22nm on a moonless night, the MercMon was so bright (originally set at 40%-brightness, but then reduced to 10%) that the captain placed a small towel over the gauge while underway because it was hurting his nighttime vision.  Once the weather turned-south, the bumpy-ride made it impossible for the towel to remain in-place over the gauge, and every time the towel dropped, the captain was once-again blinded.  Since the gauge (at-least underway, in 4-6’ seas, without time to re-read the manual) only has 10%-increments for brightness, the only option was to reduce brightness to 0%, effectively turning that gauge’s display off.

It’s unfortunate, since all of the other original SmartCraft gauges are spectacular and at a perfect brightness (under dash-dimmer control by-the-way, another feature that would be nice on this MercMon) while underway, even in complete darkness and significant seas.  The Garmin 5208 display is also an LCD-screen that is quite-bright yet somehow does not blind the night-driver while providing highly-readable information underway (set between 7%-to-8% brightness at night, 100% during the day).  The original SmartCraft gauges (manufactured by VDO)  also demonstrate well thought-out, crisp, nighttime readable displays and dials; it’s like Mercury threw-out years of development, to make a new product cheap (and keep in mind, there is nothing inexpensive about this gauge).


This MercMon will be kept for the NMEA-2000 gateway-features only and will be hidden under the dash in the future.  The original SmartCraft gauge will be re-installed in-place of this MercMon, as RPM-Synch is the most-used display-function on the Christina Rose.  The Captain purchased this very-expensive gauge assuming Mercury’s sales-literature and endorsement by WestMarine as new ECO-product of the year award recipient was reliable, however it is doubtful this product was ever tested-well before release to the public.  Nighttime brightness and readability of this gauge is terrible, bordering on dangerous.  Equally dangerous is all the button-pressing required to call-up a desired-display, worse than texting-while-driving.  It’s not often for the Captain to admit he made a bad choice, but since everyone learns from their mistakes, the Rose’s captain learned a lot about the Mercury SmartCraft MercMon gateway monitor.

Happy Wakes!  Feel free to drop me a note anytime,

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