Im looking at pedestal seat mounts for my boat. The ones I like are Springfield Plug ins with a 9" tall post by 2 3/8" wide. These will be used for my driver and passanger seat while underway and then moved to fishing spots in the boat. Thing thats got me confused here is it says they are rated for speeds of less than 5 mph??? Seriously with a 2 3/8" wide post?