I was outside the heads, Port Stephens, in my 16' plate hull tinny once when I saw one like that first pic heading up from down south. Pulled the anchor and high tailed it back towards the back end of the bay where I live. I got half way back when it hit. Thought i'd anchor up and hunch down (open centre console boat) and ride it out, then go home. The wind was so bad that it almost lifted my boat clear of the water at one stage and was very close to flipping it over (and it's a heavy 3mm plate hull boat). My only choice was to start it up and head into the wind (luckily in the direction i needed to go) and just keep slowly moving towards home. The rain was so heavy I couldn't see past the bow of the boat, and was totally relying on GPS to keep me off the rocks at the time. After 20 minutes of very scary stuff, the wind dropped, the sun came out.. you'd have never even known there had just been a storm.
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Yes I am an agent of Satan, but my duties are largely ceremonial.