So I made the player able to walk on water

 

(Runs every tick)

if(world.getBlockState(player.getPosition().down()).getBlock() == Blocks.water){
		if(player.motionY < 0){
			player.posY += -player.motionY;
			player.motionY = 0.09;
			player.fallDistance = 0;
			((EntityPlayerMP)player ).playerNetServerHandler.sendPacket(new S12PacketEntityVelocity(player));
		}

	}

 

But the player is very slow and can't jump. How do I fix this?

player.onGround = true;

Ok the player is now sinking about halfway into the water, but is moving a little faster. Any more solutions?

 

if(world.getBlockState(player.getPosition().down()).getBlock() == Blocks.water){
		if(!world.isRemote){
			if(player.motionY < 0){
				player.onGround = true;
				player.posY += -player.motionY;
				player.motionY = 0.09;
				player.fallDistance = 0;
				((EntityPlayerMP)player ).playerNetServerHandler.sendPacket(new S12PacketEntityVelocity(player));

			}
		}

	}

Since there is no easy support from minecraft to walk over water, I would suggest to either detect a jump/movement or use keybindings, and apply the correct speed, rotation, velocity, positions to the player.

 

To make it 'smooth' you could use a flying mechanism (e.g. fly at the same level as water). Though think carefully about what should happen if a player hits for example a water fall (a non horizontal waterline)