Bass Strait and Swell Direction

Looking at the bathymetry maps on Navionics leads me to ask how can there really but difference in swell direction for the entire Bass Strait? Basically anywhere East of Portland.

Why I think this is because of the Bass Strait Ridge (dont think its called that but know it has a name as ive read about it before), the clearly defined curved part where the water depth goes from roughly on average 1300m to the Bass strait waters that average around 70 meters. That depth seems to be fairly consistent before becoming shallow not too far from the coast line.

Ive been wondering for a while now and it came too mind when Craig posted a article back in May regarding bathymetry and period. Ill cut n paste the key part to my question (Cheers Craig)

"Swells start to feel the ocean floor at a depth equal to half their wavelength, and this wavelength can be calculated by taking the swell period, squaring it and multiplying by 1.56.
Wavelength = 1.56*period^2
So for a 10 second swell it only starts to feel the ocean bottom at a depth of 78 metres.
When looking at a 16 second swell though, it starts to feel the ocean floor at 200 metres.
And a 20 second swell will start feeling the ocean floor at an incredible depth of 312 metres.

I read that and think that the answer is right there, that a due West swell or a due South swell of any significane will be steered back to a SW direction.

Heres the link again too the bathymetry maps and have a geeze for yourself, love to hear some feed back and as usual, i hope my question is understandable.

https://webapp.navionics.com/#boating/settings@6&key=hxqqFwivlZ

Cheers