For a Catamaran hull setup, there are a small number of components that are secured to the transom area. This includes the strut, rudder and in some cases a cooling water pickup.
When purchasing the strut for a Catamaran Hull setup, it is important to keep in mind the depth the strut must reach. Commonly with a strut for a Catamaran Hull, the section that holds the prop shaft tends to sit further ahead of the mounting surface. This is different from a strut that would be used with a Mono Hull.
When mounting the strut on a Catamaran hull it is important to determine the final position the strut will be setup in, for the first initial run. This is due to adjustments that can be performed to the strut for fine tuning. The reference position for the strut and this will also be the first run position, is where the center prop line of the strut is even with the furthest bottom surface or edge of the sponsons. This will be the reference position and first initial run position. When mounting the strut is is important to allow adjustment room for raising and possibly lowering the unit. Allow 60% of total adjustment for raising the strut. Keep in mind when raising the strut the screws will reach the bottom of the adjusting slot as the screw remains stationary and the slot slides up. Allow the remaining 40% of the total adjustment for lowering the strut. For example if the strut allowed exactly 1” of height adjustment, 0.6” would be for raising the strut and 0.4” would be for lowering the strut. Prop shaft angle should be set to 0 degrees or neutral for the first initial run. Refer to the drawing below for a better visual of the Catamaran Hull Setup.
Rudder with Water Pickup
A rudder is essential for steering any RC Catamaran Hull boat. Select one that is best suited for your hull length. Around 15% of the hull length is a good approximation or starting point. It is recommended but not required to select or choose a rudder with a water pickup. If there is no water pickup in the rudder it is recommended to use an external pickup
Center of Gravity on a Catamaran Hull will be setup around 25-35% of the total wetted surface Hull Length.