A new auto-trimming device for Mercury outboards and sterndrives, Mercury Active Trim, helps boats plane more quickly, levels the ride, makes driving in snotty water and boat traffic easier, and, according to test reports, delivers fuel savings of 14 to 54 percent. I took it for a ride to see.
Active Trim is a computer-controlled automatic-trim system that’s available as a (pretty much) plug-in accessory for most Mercury outboards and sterndrives. Even coming from a racing background where accurate and critical trimming of the outdrive is a way of life, I think it’s worthwhile.
But my first thoughts were not positive. Why is this needed? Computerized trim control already exists. But Active Trim is GPS speed-based. Other similar systems are rpm-based. Engine rpm and trim do not always correlate properly, while boat speed almost always does. Here’s an example: Heading into a sweeping turn, you apply the throttle to maintain boat speed. An auto-trim system that’s rpm-based will increase positive trim — exactly the opposite of what you want. Merc’s system automatically decreases trim a hair as it senses GPS speed decreasing, which is the desired response when turning. Likewise, it reacts quickly to planing, increasing positive trim angle as the boat climbs out of the hole and speed increases.
Active Trim comes with five standard preselected trim profiles that cover the great majority of hull and propulsion types, including small runabouts, pontoons, bass boats, cruisers and even high-performance hulls.
You can start by entering the profile that best suits your boat type, then fine-tune as you go.
Active Trim can be ordered with all new Mercury outboards and sterndrives, and retrofitted to most late-model engines above 40 hp as long as the engine is Smartcraft-compatible. A 2 1/8-inch hole saw is all that’s needed to install the display in the dash. It can act as a stand-alone unit. It retails for about $500, depending upon the specific installation.
The Active Trim display shows the profile selected and whether or not the system is engaged — that’s it. Once engaged, touching the “on” button takes over the trimming function at all speeds. Hitting “off” on the dash display disengages it, as does manually using the standard “up” or “down” trim buttons. After overriding by manually manipulating the trim, Active Trim takes over again — simple.
I tried trimming the drives on several hulls manually to see if I could improve the top speed and fuel economy over the preset Smart Trim. I could in some cases; in others, I could not. When accelerating or turning, it’s easy to see Active Trim adjusting the drive angle ever so slightly as speed increases. At cruise speeds, it adjusts for the best overall ride; here is where a crack operator could possibly do better. Active Trim can help novice boaters, but it also allows the seasoned skipper to relax a little at the helm. And maybe — just maybe — it can teach an old salt at the helm something new.
Mercury Marine Fond Du Lac, Wisconsin