Brian Whatcott wrote in
:

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.

Hehe...look: someone paying attention! If I said "fill the drum to
leave 15 gal worth of buoyancy", would that be better?

:-)

Brian W


Yup.

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

"Richard Casady" wrote

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

Wouldn't the embedded iron and steel be likely to corrode, possibly causing
the surrounding concrete to fracture, if the ferroconcrete mixture were
exposed to continuous submersion, especially in a salt water environment?

Just curious.

Alex

On Mon, 23 Feb 2009 20:26:05 -0800, "Alex"
wrote:

Wouldn't the embedded iron and steel be likely to corrode, possibly causing
the surrounding concrete to fracture, if the ferroconcrete mixture were
exposed to continuous submersion, especially in a salt water environment?

On Tue, 24 Feb 2009 15:53:22 GMT, (Richard
Casady) wrote:

On Mon, 23 Feb 2009 20:26:05 -0800, "Alex"
wrote:

Wouldn't the embedded iron and steel be likely to corrode, possibly causing
the surrounding concrete to fracture, if the ferroconcrete mixture were
exposed to continuous submersion, especially in a salt water environment?

There is a lot of steel inside a lot of wet concrete, and it doesn't
seem to matter. What will swell and spall a crater in a street, is a
bit of coal. Always makes a rust stain as well.

Casady