:: :: Take the end cap off the boom and then you can get a
:: :: wrench on both the nut and the bolt. Just did this a
:: :: couple of weeks ago. If you need another end cap let me
:: :: know, I have a good used one.
::
:: Good idea - how did you do it? I confess I don't know
:: how the end cap is held in place.

probably with pop rivets or a couple of screws around the perimiter. You might ned to take the boom off the boat if the attachments are old and frozen. Where are you located? If in the bay area I may be able to help with the right tools and lots of FREE advice. lol