The photo of this Cruisers 300 demonstrates a perfectly trimmed ride. Note the level angle.

During most weekend outings I���ll spot a boat plow near me with the bow so high in the air, I wonder how the skipper can see in front of him. Most of the time, there is one reason for this poor showing: the incorrect operation of trim tabs. In my opinion, trim tabs are one of the most misused pieces of equipment on board a powerboat.

First of all, it helps if you have trim tab indicators. The LED type, for instance, let the helmsman know if the tabs are up, partially down, or down. The rest of the equation is up to the helmsman.(Be sure your tabs are in the up position when backing into a slip or the connecting pins from the tab to the actuators can breakwhen backing down.)

Trimming a boat to its optimum angle depends on several factors, including sea state and the helmsman���s familiarity with the boat. The more you run a boat,the more you���ll understand her nuisances. For example, I used to run a 38-foot express cruiser that would usually only need to be trimmed when we were full of fuel. All 300 gallons of diesel was under the cockpit, and as we burned fuel she began to run at a better angle. Three hundred gallons of diesel weighs about 2,100 pounds. Visualize about 10 of your hefty beer-drinking buddies standing on the bow and how much their weight affects the trim of your boat. In addition, it is key to understand what is happening below the waterline.

For the sake of clarity, let���s assume you���re operating a boat with inboard power, either straight or V-drives. Obviously the shafts, struts and props come out of the hull at an angle. Therefore the props will push water down, pushing the boat up at that same angle, either at the engine or V-drive location. Thus trim tabs are necessary on planing and some semi-displacement hulls. A good hull design will incorporate lift characteristics, which will determine how much tab is needed. If I���m testing a boat and realize I haven���t touched the tabs, it���s an obvious plus.

To properly adjust your tabs, put your GPS on the "speed over ground" display. I like to adjust the tabs after reaching full cruise rpm by pushing the switches for two to three seconds and waiting 20 or 30 seconds for the speed to increase or decrease. This has worked for me for the last 30 years. Again, as you cruise your boat you���ll begin to understand how much adjustment she needs. But be sure to monitor boat speed and rpm.

It is also important to observe the sea state, especially on the Great Lakes, where a calm day can become rough in no time. In most cases, I prefer no tab in a following sea, since a neutral tab will keep the bow high. As the boat runs off a wave, neutral tab helps eliminate abow steer reaction and prevents the bow from being pushed into the back of the next wave if the seas are stacked. In a big head sea, a neutral tab and highbow will help keep the decks drier and prevent the bow from diving like a submarine.

Remember that trim tabs function independently of each other. This can be useful for leveling, offsetting weight distribution and countering for beam seas. When the waters thaw and you���re backin the water this spring, take the time to learn the touchy-feely aspect of trimming your boat. You���ll realize a 1- to 2-knot increase by properly using your tabs, and you���ll save yourself fuel and time during your next cruise.