Lenny Rudow July 3, 2012 Lenny Rudow
Finding the right trim when running a powerboat has two major effects: it will improve the riding characteristics, and maximize fuel economy. Yet many boaters never even bother to adjust the trim much beyond trimming down for the hole shot, and up when on plane.
Why do so many boaters ignore trim? Because they don’t realize just how big an effect it can have. A few years back I was invited on a 24′ walkaround for a 20 mile journey, to an area that had been thick with cobia. But it was so rough, half way into the ride we slowed up and discussed turning around. I had noticed that the guy running the boat hadn’t touched the trim tabs once on the entire ride, and suggested that instead of turning around, he let me take the wheel for a while so he could rest. At the helm, a few tweaks of the tabs changed the ride from painful to merely uncomfortable. We made it to the hotspot, and in short order hooked up with a 60-pound cobia.
Another example of the importance of trim can be found in fuel efficiency. During the past 15 years of testing boats (well over a thousand, just for the record) I’ve compared fuel burn rates with and without trim set properly, several times. As a general rule of thumb, for every 10 GPH of fuel burn, trim angle will account for 0.1 to 0.2 GPH. One or two tenths of a gallon an hour might not sound like much, but if you put 100 hours of running time on your boat in a season, that’s 10 to 20 gallons of fuel. Would you ignore someone if they offered you 10 or 20 gallons for free, and all you had to do was flip a switch now and again? I didn’t think so.
So, what exactly is the secret to finding the perfect trim? Understanding that in each and every sea condition, it will change. There IS NO perfect trim angle for any individual boat, in any specific sea condition. Rather than finding one trim angle and sticking with it, you need to constantly adjust those tabs and/or engine trim. And not just once during a run, but sometimes every few minutes as the sea conditions or your direction of travel change. In fact, if you haven’t played with the trim after a change in direction or a half-hour or so of cruising, you should mentally remind yourself to give it a shot. Tweak it and change it back and forth until the ride feels best underfoot, and you’ll probably discover that the “perfect” trim is just a few adjustments away.