Has anyone replaced their captain's chair pedestal with an aftermarket one? I seem to always be uncomfortable in mine. It's too low and even with the bolster folded up I always find myself propping myself up when driving the boat. The adjustments just don't seem to work correctly.....
Many have done this. I just did mine last year. You've got an older boat, so the best way for us to help you is to post pics of what's existing, with as many identifying things of the current seat assembly in those pics as possible. If you've got a 6-bolt pattern to the seat post, there's a dead simple method to figure out your hole spacing, since it'll be spaced evenly and therefore easy to measure. If you've got a different one, pics will help to direct you on what and where to measure.
Getting the OEM bolts out will be your toughest challenge, and may require you to learn some new (but easy) skills, tapping and threading holes, like
@Ronnie mentioned. Getting the height you want will be the next biggest challenge, but that'll be simply checking out specs and going with what you determine you'll want.
Do you like the bolster? I found it to take up way too much space, but I have a different seat than you do. If you're not a fan, then removing it should be a matter of 4-6 bolts, and then using cushions or something else to determine what you want the max seat height of the new setup to be, and if you think you might want to raise/lower it, figure out what your minimum is that you want. Again,
@Ronnie brings up a great point about a fixed pedestal. It should end up being cheaper than an adjustable post, but you've gotta decide that, and let us know your decision and what you're looking to do.
First, pics. ALWAYS pics. Way easier to edit them to show you on YOUR setup what we're trying to say, or see what YOU are referring to.