Bennett Trim Tabs - How Do They Work?

Quick Summary: How Trim Tabs Work

• Trim tabs adjust boat pitch and roll for a smoother ride.
• Electric systems are best for smaller boats; hydraulic for larger vessels.
• Controls include rocker switches, indicators, and auto-retraction.
• Bennett Marine offers reliable upgrades and replacement kits for most boats.

PartsVu Xchange Talks Boating chatted with David Rose, Director of Sales at Bennett Marine, Connor Bluhm, an Account Manager at Bennett Marine, and Charlie Haimes, a partner with the Haimes Coleman Group, to help better understand outboard motor trim tabs. Based in Deerfield Beach, FL, Bennett Marine is a leader in trim tab innovation. The Haimes Coleman Group is a sales organization made up of highly experienced and knowledgeable marine industry professionals. They represent twenty of the industry’s leading brands, including Bennett Marine.

We had a great conversation about how trim tabs work, what’s different about Bennett trim tabs, and how to make the best trim tab product selection decisions.

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What do trim tabs on a boat do?

David: Trim tabs on a boat are adjustable metal plates mounted to the transom that control the boat's pitch and roll. They help correct listing, improve fuel efficiency, and allow smoother rides in different sea conditions. By adjusting the trim tabs, you can raise or lower the bow or stabilize side-to-side motion.

Another way of looking at it is like an X-pivot. If you were at the helm and wanted the starboard bow down, you would actually be putting the port tab down and working on that axis. For the whole bow down, those tabs would be fully deflected. To make the bow raise again, you simply retract them.

Basically, trim tabs correct your boat in a bow to stern motion or in a port to starboard listing motion. These adjustments help with weight distribution by correcting the load and may particularly help boats prone to listing.

Connor: The biggest benefit we hear from the boater is the corrections trim tabs make to a listing boat. Many customers are not experienced boaters and may not completely understand effective weight distribution. In their excitement, they may lean over, suddenly creating an imbalance. For this reason, they get the trim tabs to enable a smoother ride. Trim tabs are easy ways to improve the performance of a boat.

Charlie: It is about fine-tuning, getting the right attitude as the boat slices through the waves. You want the bow to be up a up a little higher in a following sea. In a head sea, the bow needs to be kept lower with a good set of trim tabs. With so many different boat and bottom designs, a good set of Bennett trim tabs will improve the boat’s performance.

Trim tabs help adjust your boat’s balance and performance by:

• Lowering or raising the bow to optimize fuel efficiency and visibility.
• Correcting port-to-starboard listing for smoother navigation.
• Improving ride comfort in different water conditions (head sea vs following sea).
• Enhancing speed and stability by creating an even planing surface.

What are some key differences among outboard trim tab systems?

Connor: The most common types of trim tab systems are hydraulic and electric. A hydraulic power unit or pump runs the hydraulic system. An electric system is run by electric actuators with motors, meaning no power unit in the boat itself.

For smaller vessels, there are spring-loaded tabs. For larger vessels, Bennett Marine offers heavy-duty hydraulic tabs. A good hydraulic system will take the punishment from the extra weight and work the boat does. It all comes down to what will perform best for that particular boat.

A rule of thumb is that a boat less than 30 to 36 feet would benefit from an electric system. That would allow for ease of installation and the ability to extend and retract faster. For even smaller vessels, the more affordable spring-loaded systems do not require wiring, tubing, or control inside the transom. They simply use two spring-loaded actuators located at the rear of the vessel. While on the go, they are not manually controllable, which doesn’t help with listing. Still, they do correct porpoising by getting the bow down.

David: Some people use gas pistons instead of spring-loaded. Also, there are different custom variations of dual-acting high-performance hydraulic trim tabs. Charlie has seen many of these in his years running race boats. Bennett trim tabs cover most applications whether a boat is ten feet or a hundred and thirty feet.

Charlie: For over fifty years, Bennett Marine has addressed the diverse marine market by offering spring-loaded, electric, and hydraulic trim tabs. Bennett has options for anything from a jon boat to a fast performance boat. Just about every boat out there needs a set of trim tabs to fine-tune the ride based on customers’ needs. Even on high-performance boats running at 80-90 MPH, trim tabs allow the boat to settle back down when the boat gets a little out of shape.

Are Bennett trim tabs available for aftermarket purchase?

David: Yes.Bennett Marine offers conversion kits that provide a lot of value. Although we sell replacements, if an old Bennett pump no longer works, a customer may want to try electric because the response time is faster. They may have heard how easy it is to retrofit their trim tab system themselves without having to change many components.

For older systems that still work well, it may be about upgrading the control to a touch panel that has the up and down buttons, adding a joystick, or something with auto tab control built-in. Even with a classic hydraulic system or a competitor’s system, we likely have control upgrades available. The customer is not forced into buying a specific set with a particular control—our distributors offer parts à la carte.

Connor: Besides upgrades and conversions, another big segment is replacement parts. Bennett is known for one of the best warranties in the trim tab space. Still, as everyone knows, the marine environment is harsh, which causes a great deal of damage and eventually part failure. Our distributors keep many items in stock and are ready to support our customer’s replacement and upgrade needs.

How difficult is it to install Bennett Marine parts or kits?

David: Obviously, it depends on a person’s mechanical aptitude—installing trim tabs is not for everyone. But, for the smaller spring-loaded systems, most people can complete the job fairly easily. It requires 7 screws per side and no holes that go entirely through the transom.

Electric trim tab systems require running some harnesses with power leads, which not everyone is comfortable with. However, the schematics look relatively easy, with two actuators hooked up to two harnesses moving forward to home control.

Hydraulic trim tab systems are a bit more complicated. Premier hydraulic systems, in particular, need to be installed by a master technician.

How have trim tab control systems changed over the years?

Charlie: When I first started selling within the marine industry, many boat builders didn’t have trim tab controls with indicators. Given my boat racing background, I want to know the position of the adjustable items on the boat like engine trim and my trim tabs. Without a reference, the trim tab is not as useful.

For example, the digital light indicators could have two or three lights lit up, indicating how far the trim tab is down. You can adjust if the boat is listing left or right, or port or starboard in running one direction. Upon return, in a quartering sea, you would want to adjust the tabs in the opposite direction which you would see on the indicators. If not, the boat would be listing heavily to one side

The upgraded controls make it so much easier for the beginner boater and even for an experienced boater. After getting some experience, the controls can be adjusted to previous settings that you liked, taking out some guesswork. More OEMs could benefit from taking advantage of the Bennett trim tabs.

David: To add a comment about the indicator control, a feature that pays for it in the quickest way possible is the auto tab retraction. Everyone knows retracting the tabs must be done when the boat is put on a trailer or lift. Unfortunately, as experienced as boaters can be, forgetting to retract the trim tabs just once could break them or an actuator. With an indicator control with a built-in auto tab, it retracts the tabs for you once the ignition is shut off and the power is removed. With a $140 cost difference, it could save up to $300 in replacement parts if you forgot to retract them. Another added feature is auto trim pro, which dials in how the boater likes running the boat and saves it as a favorite, making the whole experience easier next time.

How do boaters in the aftermarket decide the trim tab system that is right for the upgrade?

David: We try to lay it out on our website and provide videos to guide our customers. Also, we put together recommendation Bennett trim tabs application sheets to help. The best way, though, is to discuss with the customer what they currently have, the purpose of the boat, and what they want to accomplish with the upgrade.

The way the boats are run can vary widely between our customers. The space available can also affect what products will fit. Some customers failed to mention they have a swim platform with a ladder they use while out with their kids snorkeling and playing water sports. In other cases, the boatbuilder may have designed it in such a way only to allow certain trim tabs to fit in that particular space, and we might recommend staying with what they have.

It really depends in each case on what they have, so it works best to show us what they have and how they use it, and we’ll talk them through what options there are.

Charlie: For boats built with a custom set of Bennett trim tabs, we keep the OEM drawings for many years and have the information available when customers need replacement parts. Some of our competitors are no longer in business, making getting those replacement parts difficult. Since we keep that information, we can replace a set of plates reasonably quickly for the customer or dealer.

For new boat buyers, what trim tab questions should they ask their boat dealers?

David: Which brand of trim tabs was used is the first question, and what size is the next. If the trim tab configuration seems to be unique, ask why. In cases where the boat has a premium trim tab system, ask what is on the helm, what kind of keypad it has, what kind of indicator lights, and if it is NEMA compatible.

If the plan is to keep the boat in the water, can the dealer add zincs to prevent corrosion if the OEM has not already? As far as the trim tabs, ask what they look like and why they picked that particular set of tabs. Typically, they have a great answer based on a competitive analysis with studies of manufacturers that build comparable size boats on similar platforms with similar horsepower. The tabs we are providing them are either nearly identical or have a slight modification, to which they can tell you why that modification was made to the tab.

Connor: Commenting further on what David said, we recommend asking what kind of keypad or control the boat has at the helm. For new boaters, the indicator controls are a great learning tool.

Charlie: Make sure there are trim tabs on the boat because you want the adjustability. I also agree that the indicators help new boaters learn how to get the best ride out there on the water.

According to Bennett Marine, which has led the trim tab industry for over 50 years, properly installed tabs improve safety, fuel efficiency, and passenger comfort on virtually all boat sizes.

FAQs about trim tabs on boats

What is a trim tab on a boat?

Trim tab is a small adjustable metal plate mounted to the boat’s transom that modifies how the hull interacts with the water. Trim tabs allow you to control the bow's height and stabilize the boat laterally.

What do boat trim tabs do?

Trim tabs adjust the pitch (up/down) and roll (side-to-side) of your boat, making it ride smoother and more efficiently. They’re especially useful when a boat is listing or struggling to plane.

How does trim tabs work on a boat?

Trim tabs work by angling downward into the water when activated, which pushes the stern upward and lowers the bow. Controlled by hydraulic or electric actuators, this adjustment gives the operator more control over the boat’s attitude.

How do I adjust a trim tab on an outboard motor?

Use the manual rocker or joystick controls at the helm. Pressing down the starboard button lowers the port side trim tab and vice versa. For fixed tabs on smaller boats, the setting is usually adjusted during installation.

What’s the difference between electric and hydraulic trim tabs?

Electric trim tabs use motor-driven actuators and are best for boats under 36 feet. Hydraulic systems use fluid and pumps, offering more force for larger boats or heavier loads.

How do I adjust trim tabs on my boat?

To adjust trim tabs on a boat, use the control panel at your helm. Pressing one side lowers the opposite tab, helping balance the boat. For example, if your boat is leaning left, press the left button to lower the starboard trim tab and level the boat.