Stinger / Strut Adjustments – Mono, Cat, Tunnel Hulls
An important drive adjustment is changing the angle of the output for the stinger and strut will adjust the ride attitude of the hull.
Angling the stinger/strut on a Monohull, Catamaran, Tunnel Hull so that the prop is now higher than previously(pointing towards the sky) will result in the ride attitude becoming loose. This is also known as positive drive angle and will decrease the amount of hull drag but also decrease stability.
Adjusting the ride angle so that the prop now faces towards the lake bottom is commonly known as negative drive angle. This drive angle will push the bow of the hull in to the water increasing drag but also increasing the effect of the rudder. Too much negative angle will make the hull bite in corners. Too much bite may cause a spin out.
Raising Strut/Stinger Height
An increase in the height of the outrive will move the prop away from the water. The prop will run more shallow. This may increase output drive RPM from a reduction of load.
A decrease in height of the outdrive will run the prop deeper in the water. A deeper prop will increase the load on the motor.
Strut Adjustments – Hydro Hulls
For a Hydro style hull the effects are different. Positive Drive Angle will push the rear in to the water proportional to the prop thrust. Negative Drive Angle will push the rear of the hull in to the air proportional to the prop thrust
Raising Strut Height
An increase in height of the strut(prop line closer to hull bottom) on a hydro style hull will lower the rear of the hull in to the water. A strut that is too high may allow the hull to run too deep.
A decrease in the height of the strut (prop line further from hull bottom) will force the hull higher out of the water. This will decrease hull drag. Over doing this will cause the rear of the hull to hop along.
Trim tabs should only be found on Mono Hulls. Adjusting the trim tabs down will push the front of the hull deeper in the water. This may increase turning capability or rough water handling. If over done, at high speed the hull may spin out.
When the trim tabs are neutral or adjusted up, they do not touch the water and do not significantly affect the boats handling characteristics. The only time they are used is when they are to be adjusted downwards.
Turn fins should be mounted absolutely perpendicular to the hull bottom where they are located. They may be adjusted by the angle. Rotating the turn fin so that it lies deepest in the water will provide the greatest effect. Raising or twisting the turn fin away from the hull will slowly take the turn fin out of the depth of water. This will decrease the effect they have on turning capability. Keep in mind turn fins are the pivot point on a hull to allow it to turn.
It is common that the rudder can be adjusted by the angle. As a reference point, when the rudder is perfectly straight up and down, this will be our neutral point. When the rudder is tucked in towards the hull, this will effect the ride attitude during turns only. During a turn with the rudder tucked in towards the hull, the hull will lower or have a greater amount of force pulling it in to the water. This will increase drag and allow the hull to corner. If the rudder is rotated away from the hull it will do the exact opposite. This will tend to push the rear of the hull up. If taken too far, the prop will unload during a turn.