Where I live on the mid north coast, there has been a petition to have an ocean bath installed somewhere. I was wondering what effect this might have on the coastlines, with regard to erosion, and wave creation (wedges, sand accumulation?).
Whereabouts? Hard to gauge without a precise location.
If they're near the sand zone then they'll create erosion. I've seen plenty of photos of Cronulla before they put the baths in between South and North Cronulla and the sand would occasionally extend out much further. It can't happen now because of the backwash off the concrete wall. I guess that's only anecdotal but it matches what we know about fixed objects in the intertidal zone.
Like Ben said, would help to know where exactly you're referring to.