Dune breaks if I remember right, they're to preserve the beach and stop it washing away over time edit, breakwater, not dune break https://en.wikipedia.org/wiki/Breakwater_(structure)
Ah right so most of the structure is under the water? Was wondering what a few pieces of wood could do against the sea
I don't think it extends too far down, a few meters at best, but yeah they'll go quite far out, like a few hundred meters It's the same sort of concept as in that first picture, the lighthouse atop the harbour walls is to protect the coast and break the wave action. If the breakwaters weren't on the beach, the beach would eventually wash away, then you've got waves going right up against the wall and eventually eroding that and the land away.
Gotcha, cheers Was thinking it might have been something from decades ago for boats or something but couldn't work out how it would have been used lol EDIT - They did the other week Spoiler
I think this one from your link is what the ones I posted would have looked like originally https://en.m.wikipedia.org/wiki/Groyne#/media/File:Bourngroynes.jpg When the storm hit the other week you could see bits of wood being flung up in the air with the waves, guessing from the groynes Spoiler