When Bright Water was anchored in the Pacific Mexico open-ocean bays of Puerto Vallarta and Tenacatita, there were several days where the wind died and we wallowed in the swell, rolling from side to side, sometimes violently.
So we bought a set of four Davis Rocker-Stoppers at a marine garage sale in Seattle. We didn’t pay much and we didn’t really think we’d need them.
But when the seasonally extraordinary winds caused the swell to wrap around into the anchorage at Isla Coronados, we got the plastic cones out of the lazerette.
Davis wants you to rig them off the rail, and many people rig them off the end of the boom, but we used the whiskerpole and rigged them as far from Bright Water’s centerline as possible. It’s all about leverage. Also, the topping lift pulley wouldn’t have been fair if we used the boom and I was worried the line would chafe through. Using the spinnaker halyard to lift the end of the whiskerpole was better, I think. We rigged fore and aft guys to keep everything quiet.
We used a 10# weight belt on the bottom end of the rope, which was more than enough weight. The effect was instant and awesome. Even though Davis recommends 8 cones per side = 16 cones for a boat our size, we think four rigged this way is adequate. Bigger ocean swells may eventually prove us wrong.
You can see the sardine school in the lower right corner.
Edit: A little math. The drag force caused by pulling the cones through the water is proportional to the square of the speed, and the speed of the cones (for a given amount of rocking) is proportional to the length of the whiskerpole. In addition, the damping effect of the force caused by dragging the cones through the water is proportional to the length of the whiskerpole. So, making the whiskerpole twice as long makes the cones 2x2x2=8 times more effective. It’s Science!