trim tabs rfs trim tabs
the new compact RocketFlap Lite is a marine trim tab system
INVENTED to boost runabout hulls onto the plane automatically
for sale

home trim tabs hard lift trim tab sysyem on the plane trim tab trim tabs how they work calculate transom angle for trim tab system for sale
  on the plane ...
  Simply by utilizing a boats own forward motion while accelerating onto the plane, downward deployed trim tabs, retarded by rams, are gradually pushed up by the resultant water pressure achieving the desired LIFT to assist the boat onto the plane effortlessly ...  
    Lift only when you need it .. while accelerating onto the plane       .. not when you don't!    

From the outset, a key design requirement for the RocketFlap Trim Tab System was;
to ONLY provide Lift whilst accelerating from rest onto the plane.

In practice, however, this is not fully attainable. Installation of tabs to the transom will increase the surface area of the hull and thereby provide additional Lift. For example; having a pair of fixed tabs, positioned well above level, will always provide some Lift and therefore will affect the characteristics of a planing hull. (see fig. 1)


Shown in red - Trim Tab positioned just above level and held by a fixed strut will still provide a limited amount of Lift at the stern. Such a fixed system is a possible solution for boats that have a tendency to Porpoise eg. after encountering another boats wake while running on flat calm water, where the driver then needs to trim the motor Down/In to kill the resultant bounce .


On the whole, the vast majority of runabout sized boats have good planning hulls. However, the transition phase from being at rest to 'on the plane' will always be a performance compromise for the manufacturer. The length of the hull, size and weight of the engine, whether it's a 'deep, medium or shallow V' all affect a boats ability to efficiently achieve plane.

The RocketFlap has been designed to operate exclusively in this transition phase providing significant Lift, while at the same time minimizing it's effect on the hull once 'on plane', so avoiding the undesirable condition of 'bow steer'.

The profiles shown on the right of a runabout on the plane, illustrates the importance of why it is desirable for such an automatic trim tab system to have a neutral effect on the boat when on plane.
Figure 2

An ideal, efficient neutral condition where a boat is on plane and the propeller shaft runs parallel to surface of the water...
Figure 3

Should an automatic system exert Lift while being 'on plane' the bow plugs and the boat runs wet (bow steer) causing loss of top speed and fuel economy...
Figure 4

To compensate for the undesirable condition in (fig. 3) the engine needs to be trimmed up, causing a poor drive angle...

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