Here's what I've come up with:
I had replaced the original rivets on my aka knuckle once or twice already using the same 3/16ths stainless steel rivets that Hobie used. By the second time however, I noticed the rivet holes were becoming larger, almost 1/4" in dia. Weather this was due to movement, corrosion, dissimilar metals or a combination of all three, the holes that the rivets go into were no longer 3/16th's they were getting bigger.
I found the jay-cee sales & rivet inc. online store and had a long conversation with one of their very helpful engineers. I explained exactly what I was trying to do ie:
A boat in salt water, movement in a round joint between two aluminium fittings, the total wall thickness of the aka and knuckle joint combined and the diameter of the aka etc. This is what he suggested I use. http://www.rivetsonline.com/rivets-en/b ... ivets.html
Specifically the 1/4" Gesipa Bulb-tite Blind aluminium rivets Part# RV6604-8-06
They're sold in packages of 100 @ $41.36, plus tax or about 51 cents ea. and must be installed using a pneumatic air hydraulic rivet gun.
This is what they look like compared to the original s.s. rivets on the right:
This was on a test piece of aluminium plate about the same thickness as a aka and knuckle joint combined:
Close up view of what it might look like inside the knuckle joint:
Installed on my aka:
I only did this a month ago to the one knuckle that was in the worst shape at that time. I've been out sailing 3 or 4 times since, but so far I'm not seeing any movement in the joint area at all.
For the time being I'm very satisfied with this arrangement. They're tight as heck and there's no more corrosion around the rivet from dissimilar metals. As the remaining s.s rivets become loose I plan on replacing them using these 1/4" aluminium rivets.