[Chris Burkard]

Twin inboard planning hulls generally have small rudders. The rudders will have little affect at idle and vertually no affect in reverse. The easiest way to dock a twin engine inboard is to center the rudders and use the clutch controls to manuver around the dock. Outboards and I/Os generally can be turned for trust vectoring when docking, but on an inboard you can not thrust vector, you can only deflect thrust using the rudders and only in forward. When an inboard is put in reverse, the rudder is going to have almost no effect.

Installing larger that standard rudders may cause a loss in speed, but more importantly cause steering issues at high speed. The rudder hydraulics where designed with certain working pressures. Enlarging the rudders will certainly increase working pressures and could lead to a hydraulic failure or could lead to an inabililty to turn the wheel at all at high speeds. Most Tiaras do not have power steering. Increasing loads by increasing rudder size may call for a complete redesign of the steering hydraulics and may necessitate the addition of power steering. Larger rudders could also cause over banking in hard turning situations. The IPS Tiaras have computer controlled steering that limits how far the IPS drives can turn depending on your speed so you cannot put the vessel into and unsafe hard turn. Manual hydraulic steering cannot have multiple steering ratios based on speed. Either of these situations could be dangerous. Manufacturers including Tiara do a fair amount of research and development when designing the running gear. While items like props can be tweaked to a specific users typical loading, rudders on planning speed vessels typically should only be redesigned by licencensed Marine Architects that take into account everything in the steering system including hydraulics, rudder design, steering tie bars, steering pump and lines.

I'm not saying a rudder system could not be improved upon, just that it should be designed by proffesionals familiar with flow dynamics, hydraulic designs and steering systems.