General guidelines for choosing a trim tab size
In general the widest span tabs that will fit on the transom will be the most effective. The greater the surface area, the greater the lift. We‘ll typically recommend a 9” chord tab, but depending on available transom space a shorter or longer chord tab, or specially shaped tabs with upfins or dropfins may be advised.
As a general rule for boats with max speeds of 40MPH, choose at least one inch of trim tab span (per side) for every foot of boat length. For example, a 22′ boat would use a 24”x9”.
For speeds 40MPH and over, we’ll generally point you to one of our Performance, or Premier Line high-performance systems.
Measuring available transom space and considering limitations
Choose the approximate tab size for your boat using the sizing chart below. Make sure the tabs will fit your transom using the diagrams shown as a guideline. When measuring, disregard the strakes and follow the Vee of the hull.
The sizing guidelines below are intended to assist in the selection of tab sizes for vessels that do not currently have tabs installed by the boat manufacturer. For assistance with unique applications not outlined below, please call us.
When 12″ chord tabs are recommended
The 9″ chord is used in most applications. However, in certain circumstances the 12″ chord may be more effective:
Limited Transom Space – Boats with twin outboards or twin I/Os, or boats with transom configurations that limit trim tab span, can use 12″ chord tabs to achieve maximum lift. Using the measuring guideline above, fit the maximum span tab and use the 12″ chord.
Extra Lift – Slower boats (less than 15 mph), semi-displacement hulls, boats over 50 feet, outboard brackets or boats with any other feature that increases the need for lift aft benefit from the 12″ chord. The 12″ chord provides greater surface area, thereby utilizing more water flow and providing more lift.
Trim Tab Mounting Options
Two types of mounting hinges are available:
Transom Mount – This hinge style fits to the boat’s transom and is used in the majority of applications.
Bottom Mount – Used only when transom mount is not practical; requires a flat bottom with no strakes or other protrusions.