Having bought new oars for my S17 I thought I would try different spacing for the buttons. Collars recommended 1'11'' from the end of the oar. Very uncomfortable to row at that. As the beam is 6 foot 2'11' would bring the oars close together. I tried it out on the lake today and ended up with 2'5'' as a reasonable compromise. Suits my rowing style at least. I forgot to say they are 8'6'' oars.