rule of thumb for rivets?

Is there a "rule of thumb" for blind riveting two dissimilar materials like stainless to aluminum? For example, riveting a stainless mast hinge or block hanger to an aluminum mast or boom. Would I use an aluminum or stainless rivet?

Monel

yup - monel...though stainless will work fine. Goop up the rivet and hole with 5200 before setting it...it won't necessarily stop the electrolysis but it will keep water from pooling between the materials.

Just dont rivet aluminum to carbon, and dont use aluminum rivets in carbon.

Too far apart on the electron swapping scale.

You might find it helpful to use something like Calpico tape under the hardware to curb the corrosion between the mast and fitting. And glue/seal in rivet caps before you set the rivet if you want to make sure it's water tight.

Not sure I understand that "glue/seal in rivet caps before you set the rivet"

Care to elaborate?

This is a rivet cap or casing. Most rivets used on beach cats are 3/16" monel rivets. A common use is to attach tangs and other fittings on hollow extrusions (masts). To keep water from going through the mandrel hole on the rivet, most manufactures/ repair guys etc. use rivet caps. It's a little more reliable than a dab of silicone. These go under the hardware and require that you use a 13/64" drill rather than a 3/16". The rivets then go into these caps. I always dab silicone on them before putting them in. Another benefit is that there is aluminum contacting your aluminum mast, and the cap, not the mast will act as the sacrificial anode--sort of.

Hope that helps.

You would want to use a stainless steel rivet, and the reason for that is the cathode to anode ratio. Since aluminum is the anode when mated with stainless, a small aluminum rivet compared to a much larger piece of stainless will make the aluminum rivet corrode fast.

http://www.ocean.udel.edu/seagrant/publications/corrosion.html

Thanks for the explanation. I would have thought the opposite though for another reason. In other words, one would want the formed, blind side of the rivet to be the same as the material being riveted. I'm attaching a stainless block hanger to an aluminum boom. The galvanic action would be nil at the attachment or grip point if both the aluminum rivet and boom are the same material. Wouldn't the grip point of the fastener be the most critical area rather than the head of the rivet?

You might also try tef-gel to coat the rivet/ alum. joint.

See earlier discussion about rivets and dissimilar materials.

http://www.catsailor.com/forums/showflat...true#Post142319