It depends on what sort of data you are looking for.
WA is a big place so you will need to narrow it down a bit but a starting point should be
WA Marine to select the tide area you are looking for If you contact them they should have a database of tides going back over 100 nyears. I don't know what use that will be but they should be able to point you to where it can be accessed from.
Historical wave and swell heights are probably pretty useless to you as weather is dynamic and can't be predicted by just looking for patterns. If you are after say the maximum wave height for a location and date, then again the WA Marine mob should be able to help you out. Yes I'm an ex sandgroper. (Sandroper by birth - Queenslander by choice).
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