http://www.swellmap.com/forecast-maps" rel="nofollow - http://www.swellmap.com/forecast-maps

Swell height, family, wives the purple  or dark blue

 note tides times and current directions...wind against tide can chop up quiet quick on change of tide... about 1:45pm low tide.

Then look at wind direction and speed,,

 Also as a general rule of thumb, the iso bars.. if the distance between is as wide as taranaki to east cape/ taupo to cape reinga...then the wind speed is a go,, espec in a 6m craft.

You will notice on Sunday, wind starts in the west then moves to the SW....on the east coast you are in the lea of land... ie the land is like a shelter from the wind. As you move further out from the land the chop gets bigger..

 W / SW/ NW works well to your advantage.. get into SSW and NNW and the land shelter gets less....

 Flat rock is on the SE end of Kawau...as the wind turns to the SW.. from land that is a long distance for chop to form from nearest land...

With out going tide upto about 2pm.. westerly / SW should ok.. once that tide changes, starts moving in from the Nth, about 20 mins after Wind in the SW that could chop up ..

So I would be looking at clearing Flat rock around then , or shortly after, head closer into lea of land.. Do a bit of proposecting 

 May find as clear the Sth end of whangaroa, will hit a bit chop which should decrease the closer you get to the estraty home.

 Go over the above on a map

https://webapp.navionics.com/?ticket=ST-1493511625rNKBQNGYg0-pXbHduqG#boating@7&key=%7Chf~Eo%7Bsi%60%40" rel="nofollow - https://webapp.navionics.com/?ticket=ST-1493511625rNKBQNGYg0-pXbHduqG#boating@7&key=%7Chf~Eo%7Bsi%60%40

 and you will see how the above works, and apply to circumstance of the next trip