"Dan Listermann" wrote in message
...
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?

The 55 gallon drums filled with dirt may float because of the air trapped in
the dirt. If soaked after positioning and filling, they still won't weigh
much. Concrete blocks are something like 30-40% thier (in air) weight when
submerged.
You can "jet" pilings in with a trash pump. Last time I rented one was a
couple years ago and it cost me $25/day. In a day you can jet around a
bazillion pilings. Four of us non-professional jetted in 40 pilings in a
couple of hours.