Originally Posted by caverdan
You need to do both an inside and outside patch. The inside patch holds the air in and keeps the outside patch from blowing off. That means you need to sand and prep the inside of the boat too. I'd take it to a shop if you haven't done this kind of patching before. Check the Sotar site to see what fabric and glue to use.
Soar not Sotar....I read it wrong the first time too
That makes it Hypalon, so that answers the material and adhesive choices.
Small leaks/holes and on the river fixes are obviously worth doing yourself, but for the more serious damage I feel like the extra cost of hiring a professional is worth the piece of mind. I had a whole thing written out about recommending some local Denver guys before realizing you are from Oregon. I'm sure there are good inflatable repair guys in your area, so maybe look one of them up.
That hole looks like its right on the border between DIY and having a professional do it. If there is any question in your mind, its worth at least taking it to one of those guys and asking what they think.