Bold claims by heliocentrists, but are they actually true or scientific?
The ball-Earthers generally believe the Earth is approximately 12,756km in diameter. It is said the deepest oceans are a fraction of this, a mere 10km deep (a fraction of 0.000784).
So if we take a 1m diameter Earth-ball, and immerse it in water, the deepest oceans would correspond to about 0.78mm - pretty thin, but measurable. Now, if said Earth-ball were kept out of the water, slowly rotated once every 24 hours, those 0.78mm water "oceans" would drop from the Earth-ball by gravity long before they dried out (especially at the top of the Earth-ball and the sides, although it's possible a droplet or two would remain here and there ('though this would be quite unlike anything we observed in real life, so as to support the ball-Earth theory).
Conclusion: This bold claim made by heliocentrists is a scam, as real-world tests would demonstrate that the oceans don't remain in place around a ball-Earth.