Rivets or welds on aluminum?

[sal's Dad]

Originally Posted by FAST FRED

DON'T LEAVE THE GROUND!!! most modern jets have loads of glued surfaces and joints.FF

Yes, and when the manufacturer has hundreds of engineers dedicated to these joints, extensive lab testing, controlled factory environments and procedures, decades of real-world experience, and a regular and rigorous inspection regimen, confidence is justified.

However, using "off-the-shelf" products, minimal personal and anecdotal testing, backyard environment and skill-sets, and very low production runs (think: 1) caution is appropriate. Particularly in an evironment every bit as risky as flying. When I am out with my family in colder water conditions, a major seam failure below the waterline would mean near-certain death.

Again, if anyone has real information or experience, please share it!

Sal's Dad

[Guest625101138]

Originally Posted by FAST FRED

"I would not want to go to sea in a glued boat but should be OK for non critical bits."


DON'T LEAVE THE GROUND!!! most modern jets have loads of glued surfaces and joints.

FF

Fred
Vastly different situations - your analogy is poor.

Planes are built to rigorous standards. The longest flight for any passenger jet is about 15 hours - nearest airport usually less than a couple of hours away. They are generally in a dry, low corrosive environment. The only real load the hull experiences is during take off and landing. And some thermal cycling once a flight.

By comparison boats are typically built to much less rigorous standards - certainly most leisure craft. They are continuously exposed to the most corrosive environment. They could be on a voyage for many months with the nearest land weeks away. They could be exposed to high stress cyclic loading for days on end.

I fly most weeks but each take off I still wonder if it will be the last - so maybe I am a pessimist. I fly for my paid work. These are the things I think about because I have seen the way cracks are controlled in plane structures. Irrespective I still would have much greater concern setting out to cross an ocean in an aluminium boat relying solely on glue for its structural integrity.

Rick W.

[naturewaterboy]

I have used a 3M epoxy several years ago to glue aluminum together - not for a boat, but for some electronics. I remember testing several epoxies to see which was stronger. I prepped the surfaces by rough sanding (prob 80 grit) and acetone wash. The 3M beat the other epoxies, I remember. I recall that I had to damn near chisel the pieces apart.

Epoxy does lose strength with temperature - same as epoxy resin in a fiberglass hull. at 160 deg. F (easy to get on a dark surface in the sun) I think epoxy has about 1/3 or 1/2 it's strength -don't remember for certain off hand, but it is really substantial loss.

I remember this from composite aircraft construction - that's why composite airplanes are usually painted white, and a good reason to have a white fiberglass boat. Of course boats can be water cooled - but the top deck isn't unless you crash thru some waves....

just my rambling thoughts...

[naturewaterboy]

Oh, the 3M epoxy was an industrial product. 3M makes dozens of different epoxies.

[fdutrey]

Here's a interesting article on the Lotus Elise's chassis.

http://www.sandsmuseum.com/cars/elis...al/asauto.html

[PAR]

14 gauge or thinner material it's best to rivet, 12 gauge or thicker, weld. My Kestrel design for an aluminum ketch used 12 gauge for this reason.