Over the last week I've been doing some head scratching, trying to figure out exactly how I wanted to install these new ribs and doublers while planning for sea fins. The instructions for completing this mod will not work if you intend to mount sea fins since all the rivets are standard RV-1410 domed head rivets.
In my last post I had some photos showing the first attempt to accomodate flush rivets, and how that just didn't quite work. This time I went ahead and counter sunk the ribs... but I did it with the stainless doubler clecoed in place. This way I was able to counter sink deep enough to get the rivets flush. The holes in the rib ended up being considerably larger than 1/8"... but with the counter sink continuing into the stainless, there was a nice even hole for the rivet to sit in.
The twist in todays task was incorporating some angle into the structure to attach the blind nuts for the sea fins to. When I was talking to Robin at MAM he mentioned another builder who had cut short little pieces of 1" angle and attached them to the stringers to give a good mounting point. While I was looking at this I figured if that would stiffen things up, then running one piece of angle from the top stringer to the bottom stringer would make it even stronger. Robin said that it didn't take very long at all after putting the sea fins on the factory demonstrator for the rivets to start smoking, so he recommended something here.
So I ended up with 1 1/2" angle, 1/8" thick. Cut it to fit from top to bottom to tie the two stringers together and back the tip rib. I drilled a couple of lightening holes between the stringers... no need to over do it here!
When I mounted the blind nuts for the sea fins, I only counter sunk one of the rivet holes in the angle... the other one I counter sunk in the rib. This gave me another point where I could tie the rib to the angle to keep everything very rigid.
I've taken a number of pictures of the process to try and make it clear what I've done since there are no instructions from the factory to get you here.
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