Mercury Active Trim is intended to benefit boat owners. And boat dealers. Owners because it simplifies boat operation by automatically adjusting outboard or sterndrive trim to optimize economy and performance. And anything that simplifies boat operation is apparently a benefit for dealers, too.

mercury active trim

The Active Trim control panel has on/off buttons and a toggle for fine-tuning the trim profile, from least-aggressive to most-aggressive.

“Dealers tell us it’s the most common question they get from a new boat owner: Why is my boat so slow? It doesn’t perform like you said it would,” said Rob Hackbarth, director of controls and rigging at Mercury Marine. “This results in a service call, and the issue is often that the customer simply does not understand how to trim the boat. Dealers are really excited about Active Trim.”

Active Trim may be another excuse for old salts to roll their eyes–as they did over joystick docking control–at things that make boating more accessible to today’s consumer, but Mercury compares boating with Active Trim to driving a car with an automatic car transmission versus a manual. Why shift, or trim, if you don’t have to? Mercury says Active Trim will be available to boat builders and through Mercury dealers as an accessory in the first quarter of 2016, and will have a retail price of less than $500. It can be installed on any boat powered by a Mercury outboard that’s SmartCraft-capable, on “legacy” MerCruiser sterndrive-powered boats equipped with Digital Throttle and Shift (DTS), and on any boat powered by the new MerCruiser 4.5L and MerCruiser 6.2L engines, which are equipped with a digital trim system even if the boat has non-digital controls. The system does not require a glass helm display, just a dash-mounted face plate that measures about 5.0” by 2.5” and plugs directly into the engine control harness.

Volvo Penta and Yamaha have had RPM-based auto-trim systems for a couple of seasons. The Mercury Active Trim system is different, and patented, because its action is based on boat speed rather than engine RPM. The faceplate has its own GPS receiver. When the engine is started, the system automatically trims the drive all the way down so it’s ready to power the boat on plane. As the boat accelerates the trim moves out. Throttle up to 30 MPH, for example, and the trim will move to a position pre-determined to provide optimal economy. At 45 MPH, the system may add more trim. Throttle back and the drive trims down to an appropriate angle. And when the boat comes off plane Active Trim tucks the drive all the way down. Active Trim is programmed to stop trimming the drive when boat speed exceeds 50 MPH. Above 50 MPH the captain may add trim manually, the thought being that at this speed those last few degrees of trim require the human touch. Active Trim can be deactivated by pushing a button on the dash panel, and the captain can over-ride the system at any time through the standard trim control.

I got to demo prototype Active Trim systems on a Bryant Calandra and a Sea Ray 270 powered by the MerCruiser 6.2L sterndrive and my first question for the Merc engineers was how they developed a system that could work on so many different boats. Programming Active Trim for each boat application seems like an impossible task.

Exactly, they replied. So instead Merc surveyed hundreds of powerboats of all sizes and types, noting the trim each required to perform best at full throttle (or at 50 MPH). The survey results ranged from just 15 percent of the maximum trim of the outdrive or outboard, to close to 40 percent. Within that range, however, use of 18 to 25 percent of the available trim was typical. Mercury then wrote five trim profiles, one of which would work with any but the most extreme trim demands. A boat builder will select the profile that works best with a specific boat model. When purchased as an accessory, the Mercury dealer will have guidance on selecting the best profile, based on boat size, weight, power and other parameters. The dealer will then run the boat through a test protocol to make sure the best profile has been selected before the boat is delivered to the customer.

To protect the drive and prop in a shallow water situation, Active Trim deactivates itself when the captain trims up beyond 50 percent of the trim range. The system stays disabled until the captain reactivates it through the panel or trims down below 50 percent.

On the Active Trim control panel is a toggle switch which allows the boat owner to fine-tune the trim profile in five steps. The middle setting is the baseline, and there are two settings that are each more- or less-aggressive than the baseline. This permits adjustment for sea conditions–you want less trim to run into a head sea, for example–or passenger load; the boat may run better with less trim when there’s more weight in the boat.

During my test runs, Active Trim was invisible as it did its thing. I had to keep reminding myself not to trim. And I could get used to not having to run the trim down every time the boat comes off plane. Several times I sort of “tested” Active Trim to see if I could get a little more speed from a throttle setting by manually trimming, and I could never improve on the Active Trim setting at cruising speeds.

Because the boats were powered by the MerCruiser 6.2L, they were also equipped with Adaptive Speed Control, a feature that automatically holds engine RPM as load changes. See how well Adaptive Speed Control and Active Trim worked together when I put the test boat into moderate turn at cruising speed.

Without these features I’d likely have to trim down and throttle up to keep the boat from falling off plane or prevent the prop blowing out. Instead, the electronics made all the adjustments for me. Which is exactly the point.

Extra: Mercury will offer a “race version” of Active Trim for high-performance boats running surfacing drives that will limit trim out to the horizontal position.

For more information, visit Mercury Marine.