darts wrote:...one of my clevis pins failed, causing the mast to fall. When this happen, the tabernacle plate that is attached to the boat/cuddy ripped clean off, busting off all rivets that connected it to the boat/lower mast.
You could call this outcome almost ideal. Rivets are easy to replace and should be the weak link.
darts wrote:In addition, the tabernacle plate that connects to the mast itself is still connected, but it looks like it lost one of its rivets/pins during the fall as well, and now must be replaced.
From your story it is no clear whether the tabernacle itself is damaged (e.g. bent) or simply had the rivet shear off.
If you bend / twist a tabernacle hinge, you can get a new one from DR Marine (google for contact). They stock DaySailer-specific parts.
darts wrote:.. how and where I can find replacement rivets to repair it, and how to do this??? or how much it would probably cost to have this professionally done? Is there a way I can do this myself? If so, how does one put rivets on the holding???
If you just need rivets, I'd almost say that you should get by with properly sized aluminum pop rivets from your hardware store. When the mast is in place, the load should not be on the rivets. So they shouldn't need to be much stronger than needed to hold the tabernacle and mast foot in place when you raise/lower the mast. That's way less force than you have when the shrouds fail and the whole long level acts at the end of the mast on those poor rivets.
For a pop or blind rivet, there are two dimensions you need: the combined thickness of the material that the rivet needs to "grip". That decides whether it's a short, medium or long one (dimensions on the package). The other is the diameter of the hole. Probably 3/16" but you want a more or less exact fit.
You put the two pieces together, stick the rivet in, and it will have a bit of stiff wire sticking out. The rivet gun (also a HW store item) will grip the wire, pull it out, and in the process expand the invisible end of the rivet. When that is tight enough, the wire will snap.
If they have a choice, go for the "better" rivet gun (stronger design, longer handles). There's no telling when you'll need to do another rivet job on your boat (or a friend's boat) and you can even dream up projects after you see how easy it is.
I don't think you'd want stainless steel rivets. Having the rivet as a "weak" link is a design feature, in my view. Otherwise the damage to the mast foot/tabernacle is likely greater next time. No rivet will hold a mast up when the stay comes undone - the lever arm is too long.
For the same reason, I think you can get away with an open end rivet and one that uses an aluminum mandrel (that bit of stiff wire). While supposedly a bit weaker, matching mandrel material to rivet body cuts down on corrosion issues. Not insignificant on a boat, perhaps a bit less if you sail fresh water only.
That said, this is the kind of project where you dip your toes in (mostly lukewarm water, so to speak) when it comes to boat repairs. Not much to this one, no need to hire a professional, and it won't take you much longer than the trip to the store.
Good luck.