"Eisboch" wrote in message
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"Canuck57" wrote in message
news:wHdij.60275$EA5.19428@pd7urf2no...

wrote in message
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First, rivets are used on aircraft for the following reasons, not all of
value on a boat:

- low weight per attached foot of seam than welding
- cheap and manufacturing ease of use
- thermal expansion and flex
- can be drilled out for access/repair/inspection
- welding is more expensive per attached foot than rivets


Are other opinions welcome, yes.

I think aluminum welds are fine as long as they are reinforced or the
sheets are relatively thick. Thin sheet (seam) welding of aluminum is
prone to cracking when subjected to even a little flex as compared to
other metals. Maybe someone with knowledge of metallurgy can explain the
crystalline structure, etc. My opinion is based on experience in
industry.

BTW, I think flex is much more important in airplane wings than you give
it credit for. Next time you fly, note the location of a wing tip as the
airplane begins it's take-off run and watch it as you become airborne.
While flying in turbulence, watch the tip of the wing again. There's
quite a bit of wobbling around going on out there. Welded aluminum panels
wouldn't last long, nor would the wings if they were designed to be stiff
rather than being allowed to flex.

Eisboch

But my point being, do you want that much flex on a 17-19' boat?

I would think not. But on an aircraft, this is good. The wings are in
effect shock absorbers for up/down drafts and air density changes. But I
don't think this level of flex is needed nor desirable on a small boat.