The float serve in beach volleyball is pretty common. You can add some power behind your float serve by doing a jump float serve.
What that is is it's a mini-approach. It's not a full approach like the jump serve, which uses top spin. You toss the ball in front of you and you take a small approach and a hop and then you do the float serve contact.
With a jump float serve, unlike the jump serve, you usually use two hands to toss the ball up. When you contact the ball for the jump float serve, it's a firm hand, wide open, firm wrist.
You want to create a pop on the ball. And that creates that float motion. When you add the jump to the float serve, it just makes it that much harder to pass.
I prefer the jump serve to the jump float. The jump serve has a higher toss and allows me to come in, take a bigger approach and hit the ball harder.
But many people have found the jump float serve to be effective as well. And that's how you jump float serve in beach volleyball.