Adding Smart Tow / "Cruise Control" to Mercruiser 4.5L?

[Marcus Matos]

I have a 2016 SPX19 with a MerCruiser 4.5L, which has "Standard SmartCraft with Electronic Throttle Control". While trying to figure out how to install a Hydrophase RideSteady system, I stumbled across a mention of "Smart Tow".

The only "smart" features I'm interested in adding to the boat is the ability to set a fixed speed for kneeboarding/wakeboarding/etc. Does anyone have any information as to whether it's possible to add Smart Tow to this boat/engine by just installing a replacement gauge/system + GPS from Mercury that just plugs in to the engine?

 

[FlyGuy]

I have a 2016 21SPX with the 4.5L (ECT 4.5LMPI A1, according to the bill of sale). There is still a cable that runs from the throttle lever to the engine (It's not DTS or 'fly by wire'). AFAIK, the 'electronic throttle' just keeps a constant RPM as called for the position of that cable. PP and RSS were the only 2 options because of that.

All that to say, I was able to install the PerfectPass system (about 2 days...). It's not perfect: the boat will hunt +/- 1mph or so, and it's GPS based so current can be a factor. Still, it's 'The Marriage Saver'! We use it in the 10~20 mph range, wakeboarding/kneeboarding. It allows me to concentrate more on driving/scanning, and the rider knows they are close and consistent to the speed they asked for.

Also looked at the RSS system, and was impressed as well.

Love to know if you find a plug and replace system, just in case the PP unit fails at some point.

 

[Marcus Matos]

All that to say, I was able to install the PerfectPass system (about 2 days...).

Congrats! Did you by any chance get any pictures of how you connected it to the throttle? Here's a video of my install so far, and I'm stuck deciding on whether I should try to fabricate a bracket, or modify the throttle cable. I would REALLY like to go with a non-destructive option and would love to see how the PP was able to interface with the throttle cable.

 

[FlyGuy]

Great video! I don’t recall exactly how mine went together (nowhere near the boat or I would send a picture.) Perfect Pass has the install manual on their website - pg 4-5 of the Stargazer installation manual has Mercruiser specific - maybe an idea there? I definitely did not cut into the linkage or make any permanent mods.

Biggest mistake was not protecting the dashboard enough as I worked on it. Very easy to scratch with the back of the gauges while everything is disassembled.

 

[Marcus Matos]

Perfect Pass has the install manual on their website - pg 4-5 of the Stargazer installation manual has Mercruiser specific - maybe an idea there? I definitely did not cut into the linkage or make any permanent mods.

I had looked there for some tricks and stopped as soon as I came across this:

NOTE: PerfectPass Systems will not install on 2010-2016 Mercruiser engines if they have optional DTS (Digital Throttle & Shift).

Anyway, I looked at the manual and their photos definitely show an engine with the throttle arm still mounted to the engine, and not on a combined throttle/gear bracket like mine. Do you recall if yours looked just like mine when you pulled it apart? I'm wondering if we got slightly different versions of the engine...

 

[FlyGuy]

I'm sorry - I'd be lying if I said I remembered! It was 3 years ago now. The instruction manual looks unchanged.

I have ECT, but not DTS. I 'think' DTS means a system of all electric wires, no mechanical cables, whereas ECT is within the engine electronics that just keeps the RPMs steady in turns, cavitation, etc. There is a 'constant RPM' feature on PP that I was afraid might fight with the ECT system, but they play together just fine. Still haven't figured out what to do with that feature on PP.

Now that I'm typing, I do remember talking to the Sea Ray rep about this, as they used to offer one of the PP systems, but not on the 250hp version. That was his explanation of ECT, and he thought ECT would suffice instead of a PP type system. Tried it once or twice and then installed PP - huge improvement.

 

[FlyGuy]

My mistake - ECT is emissions control technology. Adaptive speed control is what they call the constant RPM feature.

Just stumbled across another possible new gadget - the 'active trim system'. Too much free time with the isolation policy....

 

[Marcus Matos]

My mistake - ECT is emissions control technology. Adaptive speed control is what they call the constant RPM feature.

Huh - you're right! Regardless, I'm not too impressed with the Adaptive Speed Control because it sure doesn't seem to do a good job of keeping the speed stable. In fact, it was one of the bigger reasons why I wanted to get the RideSteady system because of how much trouble it was to stay in control and on-plane while turning.

I also learned something very interesting last night - apparently the 200HP and 250HP engine are exactly the same (according to numerous reports) and the 50HP reduction is through programming.

Anyway, I actually made some progress yesterday. I still need to cut together a whole video but here's where I landed. I tested it a little on open-water and so far so good:

 

[Marcus Matos]

For anyone who might be curious - here's a (probably) final video of the process and "hack" I did to get the RideSteady installed. Although I would have preferred being able to put the engine covers back on, realistically I need to make checking the RideSteady connections a regular part of my routine anyway.

 

[Mark06208]

Is there any updates to this thread? I am in the same predicament with my 2021 SPX19 with 4.5L 250HP. I want a cruise control for my boat that can tie into the Simrad display which has the smart tow feature on it but doesn't work because I'm missing something. Can anyone help me find the parts I need to have this system work.

 

[JimTMich]

OP and flyguy, very cool on the PP hack!
Mark, I contacted Mercruiser and they highly suggested going to a local Mercruiser dealer to do the install. A little more talking and they came up with a parts list for me. My boat is a 2019 200hp 4.5. Basically you are missing the high speed can-X bus cable form the engine to the helm, a mechanical smarttow helm kit (brain box), possibly the vesselview link module(NMEA 2000 to Smartcraft translator), possibly a Smartcraft data harness...