Someone posted about this product on the Trailer Sailor board. Basically there is a vertical shaft that supports an overhead horizontal shaft. (The shafts are called spines.) A shade folds out from the overhead spine. The shade looks like a cross between a bat and half an umbrella. When opened, it is 54 inches wide by 34 inches deep. It provides enough shade for a seated individual. It was originally made as a fishing accessory. Links: http://www.pro-techt.com/ Review: http://www.tackletour.com/reviewprotechtmantis.html On the plus side: Said to set up and take down quickly. It will swivel and fold down flat. With two shades on an M-15, you could have one up and fold the other to prevent interference with the boom or main sheet. Can be removed and used elsewhere, like over a lawn chair on the back of a garden tractor. On the minus side: Costly. $120 to $180 each. Plus $30+ for each mounting base. I am not sure where or how to mount it on a M-15. A bigger boat might have a hand rail or rod holder available. No such luck here. Tod has mentioned using a golf umbrella. Which would provide shade and cost a lot less. The only drawback is you have to hold the umbrella. Does anyone have a clever idea for an adjustable golf umbrella mount? Or know of a suitable shade product?