I went out to Outer Owers 2 weeks ago. Sea state was less than one and I managed the 11 miles from Littlehampton at a steady 31 knots.
About 4 miles off all you could see was a dark line on the horizon. About a mile off I could see the rough stuff but it was only in one small patch, less that half a mile long and 100 yds off the marker it was flat calm.
Just before I motored into the rough stuff my depth sounder was showing 34 feet. 20 yards later it was showing 208 !!!
Really bizarre !
Still, its easy to get round the top end and avoid it altogether (and the deep stuff!!)