A mast, when needed and in use, is a workhorse of a boat, saving the crew the backbreaking work of rowing when it can. And, because it works so hard it deserves a nice, comfortable place to sit which is why we give them seats. Needless to say a mast doesn’t rest on the keel and get nailed down but needs to “marry” with the frame so as to remain firm but not twist or distort the frame when the wind is pushing. Here’s the fore-mast seat on the bench. When I got there it was shaped but needed the mast-hole chiseled out. It took a while but I think it came out pretty square, no?