One of the clear advantages of trimarans is that they are generally more suitable to outboard motor power than cats. Compared to inboard motors outboards are lighter and cheaper and it's easy to get the prop clear of the water when you're sailing.
On the downside they don't provide very good steering control in tight spaces, especially in reverse. Some trimaran owners get around this by creating a link between the outboard and the rudder.
That works fine if the rudder is beside the outboard on the main hull.
For trimarans with the rudders on the floats it's a bit more complicated, and more so if the design calls for the motor be able to be deployed and retracted without leaving the cockpit.
For the R42 we experimented with some geometry to see if we could effectively link the outboard and rudders using cables without inhibiting the tilt action for the outboard. The cables go slack when the outboard is raised, but can be pulled in close to the beam using bungee chords.
The combined Newsletter for Grainger Designs and Rocket Factory Trimarans
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