To paddle a board with a rudder fast you need to learn to use the rudder as little as possible. Every time you move the rudder you slow the board down unless its a quick tap that drops you into a bump. Rudders are a necessity on long 18 foot boards in Hawaiian waters but good paddlers like Aaron Napolean will tell you they hardly touch it on the 8 mile Hawaii Kai downwinder. When first getting on a ruddered board the tendency is to oversteer using the foot pedal too much. Paddle and board steering with a quick tap to the foot pedal works best for riding the bumps. On some boards you can steer them like prone paddleboards where you weight the rail on the opposite side you want to go to initiate the turn. Then when you catch the bump and step back on the board you can turn it like regular surfing on a longboard. This allows the board to flow with the ocean rather than make abrupt direction changes with the rudder that slow board down and could cause you to lose the bump you were trying to aim for. A lot of the rudder boards now have fore fins. This helps to smooth the arc of the turn and make the turns less abrupt. The photo above shows a custom Brian Bills fin setup where the back fin is actually nestled into a curve on the back of the fore fin for less drag. Boards without fore fins work well also where the bumps are big like on Maui and turning is more important that losing a little speed. Where the rudder is most valuable is paddling in a side or cross wind where you can steer the board into the wind and give your arms a break by not having to paddle on the lee side 100 strokes for 5 strokes on the windward side. Used properly the rudder can be a great asset once you get used to it. Like anything it takes practice.