My first attempt at blurring clouds and water

Last night I popped down the beach for what I hoped would be another glorious Whitstable sunset. Sadly, it wasn't great at all. Too much cloud over Sheppyey. But nevermind. I took this instead;

Taken with my D5500 and my new Sigma wide-angle lens, with a Tiffen ND 3.0 filter. It was at f/22 and 73 secs, and ISO 100. I don't think it's too bad!