chasing down a porpoising problem need suggestions

[MarshFlyer]

Once I got the plane in the air, my 12-foot Jimmy White flat bottom with a 350 direct drive wouldn't stop bouncing up and down. I tried adjusting the trim tab, but that didn't help. I noticed a slight .0625" rise about 15" in front of the transom when I checked the hull. I'm not sure if the weight at the back is too much or if that little rise is causing the issue. Has anyone else dealt with this or found a way to fix it?

 

[PropJunkie]

Your square-nose JW may hop if you place 50 to 100 pounds on the front deck,such as a loaded cooler or light person,particularly if the engine angle is off. The tab was adjusted by one of my friends,and the hull was adjusted and weight was shifted by the other. To make the ride smoother,check your engine angle and try some mods

 

[thepinnacle]

Once I got the plane in the air, my 12-foot Jimmy White flat bottom with a 350 direct drive wouldn't stop bouncing up and down. I tried adjusting the trim tab, but that didn't help. I noticed a slight .0625" rise about 15" in front of the transom when I checked the hull. I'm not sure if the weight at the back is too much or if that little rise is causing the issue. Has anyone else dealt with this or found a way to fix it?

Apart from the little .0625" rise near the transom, weight distribution may also be playing a part in throwing off the flow, try shifting some weight forward first and see if that smooths it out and if not explore other options from there

 

[trail bug 111]

Any update since May? The .0625" rise could be part of it, but if you're still chasing the bounce, you might try wedging a thin strip of aluminum or fiberglass under the slick bottom near the transom. A few folks with similar JW hulls had success with pieces around 1" wide and .060" thick. It's a cheap test and reversible if it doesn't help.