Hi DennisG01, As you can see from this photo there is a large nut that is welded to the bottom of the plate. The pylon when attached to the boat screws into the plate and this nut. When the pylon is not attached to the boat, there is the bolt hole that leads directly into the bilge /hull. As part of the pylon set up, the pylon was designed to be removed when not in use, there is a nylon plug that screws into the bolt hole to keep water from washing into the bilge. I think the theory is that the pylon is not designed to do anything other than pull tubers or skiers, it is not strong enough to be used to pull another boat or even tie up to. I am the second owner of the boat, the previous owner used the boat on a fresh water lake, where they did pull tubers around. They never removed the pylon, as a result the pylon became impossible to remove. I will be using the boat in salt water, and do not see myself pulling tubers or skiers. I do like the option of putting the pylon on if needed.
Thanks for the quick reply on that. This is the part I was worried about. This is the reason you had an issue. If that nut's threads aren't PERFECTLY aligned to the plate's threads, then that slight mismatch causes binding on the pylon's threads. It would be better NOT to weld the new nut onto the plate... or even better, grind out the threads on the plate, then use the original nut PLUS a second nut as a lock nut. This is called (don't laugh) "double nutting". The first nut pulls the pylon tight to the plate and the tightening of the second nut will bind against the first one (essentially slightly stretching the threads creating a "lock" so it doesn't undo itself).