Surfing Waves

Aloha gang
I recently bought a 11’0 Island Glass board and it seems to have a lot of side to side wobble. Right now the board has a single fin on it but its a 2+1. Will adding side fins increase stability? Also, if it does. What size would you recommend? Single fin is a 10” nsp one that the guy had thrown in with the board.

I also used the search to no avail

How wide is it?

Is it wobbly when surfing or when sitting?

How many boards have you had before? What were they?

Easy remedy to your problem......... stop looking down at your feet.

But if you’re not doing that, then the next problem is you might be too far forward on the deck and the tail/fin is not engaged. So the tail is waggling.