Hi Paul ! I made quite a few bow Sanders just like the ones that the guys have pictures. They work well!
But about 20 years ago I desided I needed a motorized one, So a friend of mine made one for me from my rough design drawings. It uses the 1/2"sanding belt .The belt is 120 inches in diameter
I don't know how to post photos so I'll try to describe it. It sits on the floor on a metal base, the mounting post is about 6ft long and it has an 1/2hp motor. We carved about 100+ Brant and 50 full size Canada Geese over the years,and this sander was a great help.
I'll try to figure out how to post a photo, not that anyone would want to make one but just for general information.
Paul Rutgers saw it in action when he visited my Scull boat and decoy shop a number of years ago before my health problem He might have taken a photo that he could post.
Paul, I even might be interested in selling it now. Bob Hayden