On Sat, 21 Feb 2009 16:45:20 -0600, Jim Willemin
wrote:

Brian Whatcott wrote in
:

Dan Listermann wrote:
I want to build two docks, one permanent and a floating one. The
floating one will be supported by 15 gallon plastic drums. I can get
55 gallon, but for a 4 x 8 dock, I worry about center of gravity
issues.

The permanent one will be built of 55 gallon drums filled with dirt.
Any issues to look out for?


Might you consider using 55 gal drums instead of 15 gallon drums, and
part fill the big drums with 10 gallons of dirt of specific gravity 4
( = 4 times as dense as water...)

That would put the CofG lower than the 15 gal drums.....

Brian W


Where do you get dirt that dense? Most rock is around 2.5 to 2.7; green
foundry sand is around 3, and that is about as dense as you get without
going to something like pig iron.

There is something called ferroconcrete. Instead of rocks, it is made
with so called boiler punchings. No longer the metal from rivet holes,
it is now punchings from bolt holes. Popular for radiation shielding,
sailboat ballast, and crane counterweights.

Casady