> << However, I have not yet installed more hardware on the boom, and I
> probably won't until I get a pop-rivet gun, which, given the
> construction of the boat, might be a good thing to get... >>
>
> Kent,
>
> Why not just use sheet metal screws? It seems to me they are stronger and
a
>
> lot less hassle than rivets. Am I wrong? That happened once before.
>
> Geoff
> P-15 Lollipop
> N. Lake Tahoe, NV
>
Hi webgang,
I recently asked for rules of thumb re: using screws in booms and masts on
Brion Toss', Master Rigger, rigging forum and got the following info:
If the wall thickness is less than 1/8" SS (stainless steel) rivets are
preferred to drilled and tapped machine screws. There simply isn't enough
wall thickness to hold the screw if it's any thinner. This is the minimum
for a screw under shearing load; for a tensile load you'd need a much
thicker wall.
I have always been told that a sheet metal screw through a boom or mast
doesn't have enough threads to hold in the long run. Typically, the threads
on a sheet metal screw are coarser than on a machine screw. However, if
you're going thru the boom/mast into another part (like a boom plug) then
it's okay to use sheet metal screw, if they're properly bedded to prevent
galvanic corrosion. Even still, drilled and tapped machine screws are
preferred.
For both the SS rivet and SS machine screw, it's important to use something
like tefgel or 3M101 as a galvanic insulator to prevent the aluminum (the
less noble metal) from disintegrating over time.
Best,
Judy B