I like to practice slinging with floating golfballs and noticed they usually curve hard left when skipping them slinging right handed. It is a bit counter intuitive with the way it spins so I assume there is some sort of magnus effect but couldn't find any info online. The info online was usually about skipping flat stones and back/front spin like the dam buster.  Stones usually go straight or bounce erratically. Anyone have any ideas or successes curving stone skips?

Wow, I love slinging at skips as the mighty "Kerlangggg" when the stone or ball hits is its own reward.
As to the effort of floating a skip out as a target ...... reeeessspppeeeeeecttt.
😁👍

https://youtu.be/EoP_bsdeotI?si=drCQsLrB5H6yBKdf
I tried filming some of my throws with different spin axis to see what is going on; it's hard to tell with my phone camera, but I have some ideas. I think with side spin the golf ball curves the same as it would in air just with greater effect. With gyro spin I think the ball is "sinking" into the water and the spin helps it climb out of the water (which might be why faster throws dont curve as much? They would skip normally?).With a relatively slow throw you can get one or two skips perpendicular to the throw. Backspin helps skips and frontspin stops skips, I assume it is the magnus effect in the water but could be something else. If the ball is not completely submerged would there be a magnus for force?

good luck figuring this out. there is probably torque from the water impacts and precession. some shots had sidespin and magnus drift before impact. it simply could be something like magnus for water on every impact