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Reply to: H18 - Torn Jib Clew

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[quote=Edchris177][quote]The only kind of rivets I've seen used on a beachcat were pop rivets.[/quote]
Pop rivets are very common on Cats, usually because many of the attachments are "blind". That is, there is no access to one side of the connection. You simply cannot get a bucking bar inside the mast, or most parts of the hull.
Pop rivets are hollow, they work by pulling a pin through the hollow rivet. The pin has a small knob at the end that expands the shank of the rivet as it is pulled through.
Normal rivets are solid shank, & are supported by an anvil(bucking bar) on one side, then peend by hammer or pneumatic tool on the other. The first blow or two serve to swell the shaft, making for a tight, waterproof connection that strongly resists the two pieces ability to rotate. The final blows form a head, so it cannot pull out. 
They are stronger & more fatigue resistant than pop rivets, hence their wide use in boatbuilding, bridges & aircraft.
If you look at the clews on Nacra sails, you will see they are all solid shank rivets, which have greater resistance to shear than pop rivets. In this case they have a small divot in the end. A small round end bar is inserted in the divot & struck, (most likely a pneumatic gun was used that contained the small nub, thereby rendering the process simple & quick, literally one pull of the trigger)resulting in the center peened end you see in the photo. You can see there is not much material on the backside, two decades of corrosion, & the little ring tends to fail first, allowing the plates to separate.
Normal rivets have the entire end flattened, it is a stronger end, but doesn't look as good, especially if some monkey just wails on it with a hammer. The other reason center peened was probably used is the end result is an almost flush fit, perhaps more desirable than the end that would normally protrude, leading to chafing of material & maybe flesh.
I don't have a better photo, but this shows the small ring left on the backside of the rivet. If your sails were done this way, give a close look to the head & clew plates. I have one ib that shows most of them ready to fail.
[img]http://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=88958&g2_serialNumber=3[/img][/quote]

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