Lake Balaton local transport

Hi, I'll be staying in a cottage near Balatonfured for about 10 days in
July. How good is the public transport from Balatonfured to other cities
on the lake? Is it possible to go on a day trip from Balatonfured to
Siofok, for example, using only public transport?

Google found me lots of links for hotels, attractions, activities, etc
for locations all around the lake, but inter-city transport logistics
seem to be hard to find (in English, anyway.) Trying to do this without
a car.

TIA for any help.