Hi Scott,
I was not trying to be elusive in my post, but simply pointing out that if your boat is set up this way, then you will burn out some of the smaller torque servos like the 645MG. The solution is of course to install something with the power to handle the loads with 1:1 levers. Simple.
I use a slightly different set up in my boat where the servo arm does in fact travel more than the rudder arm. The gear ratio around amidships in this set up is of course 1:1 but as the rudder angle increases, the gear radio improves and helps the servo work easier. Out at full lock, the gear ratio grows to about 1.2:1. Here is a link to an illustration of what a full size boats steering system is set up like using this system. Not sure if this is the reason I still have the same 645MG in my boat that it was built with but it may be.
Hope this helps...
http://www.google.com/imgres?imgurl=htt ... CD4Q9QEwAA