Vertical lines/pattern on surface

Hi!
I have an issue where my prints overall gets good results, but the surface gets this weird pattern forming vertically on my prints.
I have tried slow down the prints to 20mm/s and travel to 70mm/s but it does fix the issue.

The problem is visible on the image on the side of the hull of the ship. Also on the cabin it’s visible, six prominent lines. It’s forming mostly on vertical surfaces, so if the surface is “leaning” i see less of the issue.

Does any one know why this happens and what to do to minimize this?

Thanks!
Viktor