How to Choose Boat Trim Tabs: Types and Sizing

Trim tabs are one of the simplest upgrades that change how a powerboat feels. They help the boat get up on plane faster, keep the bow from pounding, and level a boat that leans to one side. But the range is wide, from small electric kits for a 12-foot skiff to hydraulic systems for a large cruiser, so the right choice depends on your boat. This guide covers how trim tabs work, the three main types (automatic, electric and hydraulic), and how to size a set.

Always follow the manufacturer's sizing chart and installation instructions. Tab size, placement and wiring depend on your hull, so check the maker's chart for your boat length, weight and engine horsepower before you order.

What Trim Tabs Do

A trim tab is an adjustable plate mounted on the bottom of the transom, one on each side. Lowering a tab pushes water down at the stern. That lifts the stern and brings the bow down. Raising it does the opposite. Because there is one on each side, you can adjust them separately.

• Get on plane faster: lowering both tabs lifts the stern and shortens the time spent with the bow high.
• Lower the bow in a head sea: bringing the bow down improves the ride and your view over the bow.
• Level the boat: if the boat leans because of an uneven load or crosswind, lower the tab on the low side.
• Run at a better trim angle: a boat running level can be more comfortable and efficient at cruise.

Automatic, Electric and Hydraulic Trim Tabs

Automatic trim tabs

Automatic tabs need no switch and no wiring. Lectrotab Smart Tabs use a nitrogen gas actuator that holds the tab in the right position as you load and maneuver the boat, so there is nothing to adjust underway. They are an entry-level choice for smaller boats and are sized by boat length and engine horsepower, from 7" x 8" tabs for 10 to 12 foot boats up to 12" x 9" tabs for boats up to 22 feet. Because they self-adjust, you give up the ability to level the boat by hand.

Electric trim tabs

An electric actuator on each tab moves it up and down from a 12V switch at the helm. Electric kits are a common choice for small and mid-size boats because installation is straightforward and they let you adjust each tab yourself.

• Lenco Marine offers electric kits in a wide range of sizes, including edge-mount and limited-space designs, with switch options such as double rocker and LED indicator.

Shop: Boat trim tabs, including Lenco kits and Lectrotab Smart Tabs.

Hydraulic trim tabs

Hydraulic systems use a pump and cylinders to move the tabs. Bennett Marine makes hydraulic trim tab systems in a range of sizes, such as 12x9, 18x9 and 24x12, usually supplied with an indication unit at the helm. They suit larger boats and owners who want a hydraulic system.

How to Size Trim Tabs

Tab size is matched to the boat. As a starting point, manufacturers size by three things:

• Boat length: longer boats need bigger tabs.
• Boat weight: a heavy boat needs more lifting force than a light one of the same length.
• Engine power: more horsepower generally calls for larger tabs, as listed on each maker's chart.

For example, Lectrotab lists a 9" x 8" Smart Tab for 13 to 15 foot boats with 30 to 40 HP, and a 12" x 9" Smart Tab for 18 to 22 foot boats with 150 to 240 HP. Lenco sizes by tab dimensions such as 9" x 12" and 12" x 12". Use the maker's chart for your hull, and ask us if you're unsure which size fits.

Also check the transom: you need a flat bottom surface of the right width on each side, and room for the actuator. Limited-space and edge-mount kits exist for tight installations.

Switches and Controls

• Rocker switch: a simple up/down switch for each tab.
• LED indicator switch: shows where each tab is, which helps when running level.
• Indication unit (hydraulic systems): a gauge at the helm that shows tab position.

Protect the Tabs: Anodes

Trim tabs sit in the water and can corrode, especially in salt. Replaceable anodes on or near the tabs help protect them. We carry anodes for specific tab and engine fits, including Tecnoseal anodes made for Bennett tabs.

Shop: Boat anodes.

Quick Checklist

• ☐ Note your boat's length, weight and engine horsepower
• ☐ Choose automatic, electric or hydraulic
• ☐ Match the tab size to the manufacturer's chart
• ☐ Check transom space for tabs and actuators
• ☐ Pick a switch or indicator you'll be happy with at the helm
• ☐ Add anodes to protect the tabs

Shop Trim Tabs

Browse the TrestleThorn trim tab collection. Free shipping on orders over $99, with 30-day returns. If you give us your boat length and engine, we'll help you find the right size.

Frequently Asked Questions