Glenn,

FWIW: The Diesel tanks on Viking Star are 42 years old 1/4 steel and
are just fine. I scrapped down surface rust and repainted them this
last Spring, so I was all over them :-)

So, Steel does work well, as long as you keep water off of them.

( A dock mate with a 15-20year old CHB is looking to replace his
tanks. Engine room vents are set up to allow sea water ready access
to the top of the tanks.....)

One thing that I attribute to the good shape of my tanks is the fuel
pickup is at the bottom of the tanks, and the tanks are kind of wedge
shaped... At least in my mind, this has prevented standing water
from sitting in the bottoms of the tanks.

I have seen people talk about putting in a small 'well' or sump in
the bottom of tanks, and have the dip tube go into that well. That
way, and water in the tank will make its way into the well and at
least most of it will be drawn out.

-al-



On Thu, 16 Oct 2003 20:56:19 -0400, Glenn Ashmore
wrote:

I am beginning to wonder if locally built aluminum tanks are a good
idea. Every shop around here is tooled up for 6061 but marine tanks
need to be 5000 series. I will have to supply my own 5086 and TIG
welding rod and the best price I can find is in New Orleans. $130 a
4x10 sheet plus about $100 shipping. Still, a lot better than $300 a
sheet in Atlanta but not as good as $65/sheet for 1018 mild steel locally.

If I go with aluminum I think I will have to machine my own fittings.
There are very few sources of 5000 series aluminum fittings and the
selection is limited. It will be fairly simple to mill and tap some
NPTF fittings from 1" round for welding onto the tank.

I would like to hear some discussion of mild steel vs aluminum. Total
cost of mild steel tanks is about half that of aluminum but weighs about
twice as much. In this case a pair of custom 40 gallon would cost $600
in aluminum with some effort on my part to get the alloy vs $320 for
mild steel and weigh 72 pounds vs 125 for steel. From what I hear, a
well painted and installed steel tank will last just as long as
aluminum. Longer if the aluminum is not properly installed.