Dometic Trim Tabs
Dometic™'s SeaStar Standard Trim Tabs are an electrically powered system that uses an intelligent actuator and an intuitive dial controller that puts precise control at a user's fingertips. Most trim tabs require at least a minimal understanding of how they work, but the new control unit sets apart the SeaStar tabs from those operated with tactile switches. The controller is intelligent, yet it is designed to be simple for an operator to grasp quickly.
"Today's modern vessels are becoming smarter and more connected," said Eric Fetchko, President of Dometic Marine. "With this new introduction, we've taken trim tab technology and performance to a new level for boat builders and boaters alike. This will be a true game-changer for the industry," Fetchko added.
To adjust the boat ride, the captain turns the dial in the direction he wants to level the boat and the actuators respond to adjust the ride. There are also individual Bow Up and Bow Down inputs for manual adjustment of ride height. A favorite button lets a boater save the desired tab position. This makes it easier to find a boat's "sweet spot" ride position with the proverbial touch of a button. The Home button returns the tabs to the starting position.
LED position indicators make it easy to monitor the tabs' position and the digital controller has Auto Brightness that senses ambient light conditions and adjusts the dial brightness for optimum visibility.
Dometic uses a fully electric system including the actuators that reduce the overall complexity of the system. The lack of hydraulics means no possible leaks or need to add fluid. Dometic says the electric system also increases long-term reliability. For instant response, quieter operation and a better boating experience, the actuators have a planetary gearbox, high-torque DC motor and free-wheeling ball-screw mechanism.
The tabs are protected by a rugged two-piece housing that minimizes possible water-intrusion points. They feature dual housing seals with the rear seal in a protected bushing area and a wiper that removes particles from the shaft.
Heavy-duty 12-gauge, 304 stainless-steel tabs complete the system and feature 316-grade stainless-steel fasteners, 14-gauge stainless hinges and ¼" (.64 cm) thick hinge pins for added strength.
Dometic engineered the new tab system for use with sterndrive and outboard-powered boats with up to quad engines. It can be paired with SeaStar™'s Optimus Electric Steering System, joystick control and digital shift-throttle systems.
Dometic™'s CAN-based actuator can be used as a standalone component that can be integrated with a boat's control system. For example, using connected technology, drivers can precisely adjust the size and shape of wakes for surfers and boarders.
For the uninitiated, trim tabs are plates installed in pairs that are used to help control the pitch and roll of a boat by directing water as it flows past the transom. They harness the hydrodynamic forces by moving water so the boat must be in motion for tabs to have an effect.
When a tab is lowered, the directed water flow exerts an upward force at the stern of the boat. Lower both tabs at the same time and the upward left at the stern forces down the bow (known as pitch control). If one tab is lowered, it will force down the bow on the opposite side, giving the operator roll control. The combination of the boat's pitch and roll is the boat's attitude.
By adjusting the boat's attitude, the operator can get the boat on plane more quickly, stay on plane at lower speeds, increase top speed, correct a slight list, improve ride quality and operator visibility, reduce porpoising and improve fuel economy.
The dash-mounted dial controller is designed for intuitive operation. If you can turn up the volume on a radio you can trim your boat with this controller. Let's take a look at the basic functions. The corresponding numbers from the photo are in parentheses below.
The System Status Indicator (6) displays the status. Steady green means it's ready to go. Flashing cyan means the favorite position has been memorized. Flashing blue means the LED brightness adjustment mode is in manual mode. Flashing yellow indicates a non-critical fault while flashing red means a critical fault that must be addressed.
The tab-position indicator LEDs (2 and 7) are self-explanatory. They show the position of the port and starboard tabs. When they are fully retracted, a single LED shows at the top. As the tabs are deployed, the indicators illuminate to show the position of the individual tabs.
Bow Down (4) lowers both tabs simultaneously. This causes the bow to drop. Hold the button until the desired pitch is achieved.
Bow Up (9) raises both, which picks up the bow. Hold the button until the bow is at the desired height.
Control Dial (3) rolls the boat in the direction of rotation to level the ride. Rotate the dial to starboard (clockwise) to lower the port tab and raise the starboard one. This causes the boat to roll to starboard. Turn the dial to port or left for the opposite effect. Roll sensitivity refers to how far the tabs move for a given movement of the control dial. The default sensitivity will work for most uses, but the sensitivity can be increased or decreased, too.
Press the Home button (8) once to retract the tabs to their default position. Use the button when the driver encounters difficult sea conditions and needs to raise the bow, when loading the boat on a trailer and when preparing the boat for lifting. The tabs automatically retract to the home position when the ignition switch is turned on or off.
Press and hold the Favorite button (1) for three seconds to save the current tab position. Press this button at any time to automatically set the tabs to the favored position.
Finally, the Auto Brightness button (5) uses an ambient light sensor to automatically adjust the LED brightness. This function can be disabled for manual adjustment by pressing and holding the favorite and home buttons together. The status LED and starboard position indicator LEDs will flash blue to indicate that the system is in manual brightness mode.
When deciding where to mount the tabs, there are several things to consider. Make sure everything has been considered before a drill is ever grabbed. The outboard edge of the tab should be 1" to 4" (25 to 100 mm) inboard from the chine. The farther outboard the tab is positioned, the more effective it is in controlling the side-to-side position of the boat.
The edges of the tab should be at least 2" (51 mm) from a hull strake. Also, to avoid interference with the engine, the tab must be at least 8" (205 mm) from the lower unit's centerline.
There are different tab configurations available and they will have different transom-height (TH) requirements. The actual transom height will vary with the transom angle, so the maximum value for TH is shown. The image below shows the standard, pocket and edge mounting options.
The kit comes from Dometic with step-by-step instructions for installing the tabs. All the hardware and wiring. The installer will need to supply marine-grade adhesive caulking. The controller is installed in a dash that is 14" to 1.5" thick and needs a 2.5" (64 mm) hole. The wiring harness complies with American Boat & Yacht Council (ABYC) and International Organization for Standardization (ISO) standards.
The power draw when installed is 9 volts minimum and 16 volts maximum. The 2.2" (57.15 mm) stroke actuator weighs 3.6 lbs. (1.6 kg) while the 4.25" unit weighs 3.9 lbs (1.8 kg). The controller checks in at .5 lb. (.24 kg). The tab weight varies with size and is estimated at .036 lb./sq. inch. (2.54 gram/sq. cm), exclusive of brackets and hinges.