Engine Repower 2020: Part 6

Learning the pros about a Mercury Active Trim install.

July 21, 2020

We’ve been documenting the repower of our 2020 project boat with a 250-hp Mercury 4 Stroke. The powerful engine boasts a new V-8 design and a host of feature that promise deliver myriad performance gains ( Our comprehensive on -water test is coming soon! Look for it!)

We’ve also been listing the many reasons a boater might choose to repower beyond performance and reliability. With a new engine comes the latest technology and one feature installed along with our test engine will be Active Trim. Below are two shots of the Active Trim control panel, just installed at our project boat’s helm.

Closeup of Mercury Active Trim installed
The Active Trim control panel provides for one touch ON/OFF functionality as well as for activation of multiple trim profiles the boater can save for varying repeatable conditions that individual boating styles. (Tubing for example; or holeshot; heavily loaded, etc.) Kevin Falvey

Mercury Marine’s active trim enhances fuel economy and ride by automatically trimming the engine(s) to suit the conditions. It is unique in that it is a GPS-based trim system that uses changes in speed to make changes, a better method, I think than other trim systems which use changes in engine rpm. Higher engine rpm does not always mandate higher trim; it may just be that the boat is more heavily loaded, for example.


Active Trim responds to maneuvers, like turns, and changes in speed: accelerate and the engine trims up; decelerate and the engines trim down. That’s a simplistic way to put it, since, like an experienced boater, Active Trim makes continual changes to trim for optimum ride comfort and fuel efficiency. We’ve run test boats with Active Trim for several years now, but this repower project will allow us to “live with” the system, so look for a follow on report.

Active Trim control panel
Active Trim’s controls make it easy to turn on or off. Courtesy Mercury Marine

By the way, Active Trim is probably not a DIY add-on. For one thing, it requires wiring-in a dedicated CPU, like the computer that runs the engine. For another, a Mercury Service Tool is required for many installations, such as making it work with Smart Craft Guages We are happy to have certified technicians, like the pros at Hampton Watercraft and Marine doing the install.

I know some of you are scoffing. “Who needs automatic trimming?” Well, I’ll answer that in several ways, starting with the fact that one of Boating’s most enduring and clicked on articles ever is this one: How To Trim Your Boat During Turns. A bunch of people apparently want it.


Secondly, we’ve used Active Trim, as stated, and really couldn’t “beat” it. Active Trim trimmed the boats just as appropriately for the situation as our test team members did. And by the way, our team runs more than 100 boats a year. They know how to run boats, if I do say so myself. Anyway, Active Trim has an OFF switch. In fact, all you need to do is hit the trim switch on your control box and manual control is restored. So, by all means, trim manually. But perhaps when your brother-in-law or other inexperienced crew member asks for a trick at the helm, you’ll then re-engage the system.

Finally, why fight it? Technology is a good thing. I have a childhood memory of my grandfather decrying my dad’s purchase of a LORAN because it indicated he might not know how to navigate, which was not true. Who today would give up GPS? (“Don’t you know where you are?”) Or, fuel injection? (“Don’t you know how to prime and choke an engine without flooding it?”) Or, hydraulic or power steering? (Weaklings!) Is anybody returning a car or truck to the dealer because of anti-lock brakes, power windows or auto-dimming headlights?

Auto Trim is a great feature and we look forward to enjoying its convenience and efficiency aboard our project boat. Look for a comprehensive report from the water coming soon.


Learn more about our repower with Mercury Marine.

Active Trim

Active Trim is compatible with:


Mercury FourStroke outboards from 40 to 400 HP

Mercury SmartCraft-capable two-stroke outboards

Mercury SmartCraft-capable gas and diesel sterndrive engines


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