Right on! Get that sucker out on the water!

Sorry I missed this party, but I'd like add a few things.

First, there is only one place on a H16 where an alu rivet is acceptable, on the post '95 jib traveler car adj block in the corner casting, which your '81 doesn't have. That's it! The loads on your mast base while raising the rig will shear the rivets. I've seen it happen alot. Also the alu rivets will work and bend, and eventually your mast base will become loose. Stainless or Monel will fix it right! Get a few extras to have in your spare parts kit. Get a Hobie catalog and call a dealer or cross reference the rivets for size. Learn to love stainless rivets, they hold your entire boat together.

Of course with 5200 gluing that sucker on you might never have that problem...which brings me to my second point. Just use silicone to seal it! A part as vulnerable to breakage as a solo-stepped H16 mast base shouldn't be 'permanently' adhered. You'll probably be changing it again at some point and breaking the 5200 is a lot of trouble sometimes.

There's a block off plate inside of the mast that you can access once the base is off. Goop that entire plug with a good layer of silicone and you'll be good. And really, I don't even goop up the base with anything, it's not necessary, but you can if you want to.

Hook up with your local fleet and sail on!

J