One of my buddies sometimes runs three riggers on his 16' Double Eagle. From what I have seen he pulls it off by using side plane pancake weights on the side riggers and not a lot of tight turns to keep the gear away from the center transom mounted rigger. It seems to me if the current in JDF is nasty he limits it to two riggers.
I only run two riggers on my model 2200 Glasply and If I want a third I put a line out the back on a trip planer or stack lines on the riggers. I stack a lot less than I use to. To lazy, and to much hassle I guess. The trip planer line was doing well this year for Ho's with a spoon and no flasher.
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The Feds did not give us our once every 4 years, late Sockeye opening, so less need for a lot of lines.