Nina and Pinta Racing Home, 1493.
I think I've posted the top image before but this one is of better quality.
A photo of UK marine artist Geoff Hunt using a mahl stick: a support for the brush hand, padded at one end so as not to damage the canvas. A mahl stick is particularly handy for detail work... and for fending off stray animals who wander into the studio.
Here's a link to instructions for making your own mahl stick: kimcpell artblog
Geoff's work combines painstakingly accurate detail with dramatic compositions.