Steve,

I've seen tanks made the way you suggested, but with the tank top oversize
so it extended an additional inch-plus on either side. This was for
suspending the tank by the lip. With all the pounding that a boat goes
through, I feel concern that the top weldment would be prone to fatigue and
cracking. OTOH, I do know lots of people do it this way (1/8" sides/bottom,
3/16" top). What do you think?

Brian


"Stephen Baker" wrote in message
...
Brian D says:

Add
baffles, I think 20" to 30" apart? Stephen? What's the spec here?

No spec listed, but 30" or so is reasonable. The other thing to make sure
of
with baffles is that the size of the holes does not exceed 25-30% of the
cross-section area.
On alu tanks, I would recommend as little plug-welding as possible, say
limited
to the top surface. (i.e. build the tank without the top, then insert
baffles,
then close) Each plug becomes a hard point, albeit small.

Steve

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.

Ron White wrote:

I had my aluminum gasoline tanks built by Ezell Industries one of the
three
marine tank builders in Perry Fl. I let them decide where the baffles
were
( a wise move) also they provided the tank fitting and valves which
some of
need to be al. rather than ss or brass. One thing to consider also is the
pickup tubes, they made these with nylon? tubing swaged onto the al
tank top
fittings. Some other people I talked to were not up to speed on the
issue of
not using metal pickup tubes as they are subject to vibration and
fatigue.
Wouldn't want the pickup to break!!! I was very happy with Ezell and the
good work they did.
Then Painting, which I did. This system is my standard and I use it on
any
alum. thing I make for boats.
1, clean with acid ectching solution ( like, Ditzler DX533)
2 prime with dupont Variprime 615S self etching primer.
3 finish with several coats of 2 part epoxy primer.
For exposed alum. things, add about three finish coats of a urethane
enhanced enamel like Limco 1234.
All of the products are availble from automotive distributers I think the
key is using the variprime as is bonds to aluminum like nothing else I
know
of..



Either aluminum or steel will probably outlast both you and me. I've
seen diesel tanks for equipment on trucks made from steel that have
never been painted that were over 30 years old. I'm thinking about
making mine out of steel, but I plan on some type of coating inside and
out, just not sure what brand yet. Weight is no problem for me with a
steel boat and no plans for racing, just cruising. I would think that
would be a major deciding factor for you. Can you stand the weight.
Cost is always a major deciding factor for me. I have to build on the
cheap. I would think you would have more resources available. Is $300
or $400 a deciding factor? What about a poly tank? I'm sure you've
priced those, about the same as aluminum, but they're ready built.

Good Luck,

Donald

--
I'm building a Steel Robert's 434. You can sneak a peek if you wish by
clicking on me link below.
http://bellsouthpwp.net/d/o/donrayp/
'USA, Home of the best
politicians money can buy'

Brian says:

I've seen tanks made the way you suggested, but with the tank top oversize
so it extended an additional inch-plus on either side. This was for
suspending the tank by the lip. With all the pounding that a boat goes
through, I feel concern that the top weldment would be prone to fatigue and
cracking.
OTOH, I do know lots of people do it this way (1/8" sides/bottom,
3/16" top). What do you think?


I'm not exactly fond of that method. As you say, too risky. If you want to
hang something make up a bracket properly sized, and then all you have to
replace is the bracket if it fails. THat's the same reason why my stereo
system is component rather than "boom-box" style. I don't have to replace
everything coz the turntable dies (yes, I'm that old ;-))

I love things that work, and can be depended on. That includes gravity. If
gravity will hold something in place when static, then a simple strap to take
care of the dynamic situation is all you need. And it's cheap!

Steve

Donald Phillips wrote:

Either aluminum or steel will probably outlast both you and me. I've
seen diesel tanks for equipment on trucks made from steel that have
never been painted that were over 30 years old. I'm thinking about
making mine out of steel, but I plan on some type of coating inside and
out, just not sure what brand yet. Weight is no problem for me with a
steel boat and no plans for racing, just cruising. I would think that
would be a major deciding factor for you. Can you stand the weight.
Cost is always a major deciding factor for me. I have to build on the
cheap. I would think you would have more resources available. Is $300
or $400 a deciding factor? What about a poly tank? I'm sure you've
priced those, about the same as aluminum, but they're ready built.

I don't think interior coatings on diesel tanks are a good idea. Diesel
is not going to attack the metal and is a pretty good corrosion
preventive. Any coating carries the possibility of flaking off and
finding its way into the filters.

$300 would not be a deciding factor but now that I am on the down hill
side of the project I find Everett Dirksen's comment about "A billion
here, a billion there, pretty soon we are talking real money."
particularly relevent. :-)

I checked every maker of poly tanks but could not find a shape that
would work without wasting a lot of space or leaving the COG of the fuel
way to high and getting molds made for custom tanks is way to expensive.

I considered building my own out of glass/epoxy but I don't like the
risk. I built two water tanks and found it took a lot of effort to get
really solid laminations in the corners. If there is even one pin hole
there will be some weeping. I can live with a little fresh water
weeping but not diesel.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Did you check Ronco for a tank? They make more stock shapes than anyone I
know, and are very easy to work with. http://www.ronco-plastics.com/.

I'd stick with regular steel for the tanks if you can't find one at Ronco. I
have a pair that are 17 yrs. old and fine. You are right about the inside,
the diesel is a good anticorrosion treatment, as long as you keep the water
out. The outside should be painted with a good coating of some kind, and the
bottom should be supported so that air can circulate under it. Obviously,
you've got to keep the water off the top of the tank as well. Be sure to
have the maker put a sump with a dip tube from the top in the tank so you
can suck out any water that might end up in there.

"Glenn Ashmore" wrote in message
news:EoRjb.78877$sp2.14422@lakeread04...

Donald Phillips wrote:

Either aluminum or steel will probably outlast both you and me. I've
seen diesel tanks for equipment on trucks made from steel that have
never been painted that were over 30 years old. I'm thinking about
making mine out of steel, but I plan on some type of coating inside and
out, just not sure what brand yet. Weight is no problem for me with a
steel boat and no plans for racing, just cruising. I would think that
would be a major deciding factor for you. Can you stand the weight.
Cost is always a major deciding factor for me. I have to build on the
cheap. I would think you would have more resources available. Is $300
or $400 a deciding factor? What about a poly tank? I'm sure you've
priced those, about the same as aluminum, but they're ready built.

I don't think interior coatings on diesel tanks are a good idea. Diesel
is not going to attack the metal and is a pretty good corrosion
preventive. Any coating carries the possibility of flaking off and
finding its way into the filters.

$300 would not be a deciding factor but now that I am on the down hill
side of the project I find Everett Dirksen's comment about "A billion
here, a billion there, pretty soon we are talking real money."
particularly relevent. :-)

I checked every maker of poly tanks but could not find a shape that
would work without wasting a lot of space or leaving the COG of the fuel
way to high and getting molds made for custom tanks is way to expensive.

I considered building my own out of glass/epoxy but I don't like the
risk. I built two water tanks and found it took a lot of effort to get
really solid laminations in the corners. If there is even one pin hole
there will be some weeping. I can live with a little fresh water
weeping but not diesel.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Keith wrote:
Did you check Ronco for a tank? They make more stock shapes than anyone I
know, and are very easy to work with. http://www.ronco-plastics.com/.

My holding tanks are Roncos. No question that Ronco has the best
selection and best quality but the last time I checked they only build
water and holding tanks. HDPE is fine for water and holding but not for
diesel. They do use cross linked PE in their industrial chemical line
but for some reason they don't want to use it in their marine line.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

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.

OK, Check with Ezell Industies Perry Fl. they made my tanks with 5052 H2 and
they were beautifuily done. Mine were 100 gallon but the prices you
mentioned should no problem not that money makes any difference. phone 850
578-2558 Dave Miller
Try also Rds Mfg also in Perry 850 584-6898
no personal experience with Rds but they make for some nice boats I have
been on.
Get some pro help here and move on to some good stuff like sanding and
grinding. I do hope you take take my advise on priming first with self
etching primer! The dupont Variprime has chromates as well, good for you
too.

--
Ron White
my boatbuilding web site is:
www.concentric.net/~knotreel

Steve, or an aluminum expert:

In general bends are better than welds (in aluminum) since you don't have
the heat treatment hardening of the tank in the area of bends, but do in the
area of welds. What if the aforementioned lips on the side, the sides, and
bottom, were all made from one sheet that was bent to make the shape. The
end caps would be welded on, as would the lid, but the welded-on lid would
not be carrying the weight. Is there any issue with bends becoming weak?

Brian


"Stephen Baker" wrote in message
...
Brian says:

I've seen tanks made the way you suggested, but with the tank top
oversize
so it extended an additional inch-plus on either side. This was for
suspending the tank by the lip. With all the pounding that a boat goes
through, I feel concern that the top weldment would be prone to fatigue
and
cracking.
OTOH, I do know lots of people do it this way (1/8" sides/bottom,
3/16" top). What do you think?


I'm not exactly fond of that method. As you say, too risky. If you want
to
hang something make up a bracket properly sized, and then all you have to
replace is the bracket if it fails. THat's the same reason why my stereo
system is component rather than "boom-box" style. I don't have to replace
everything coz the turntable dies (yes, I'm that old ;-))

I love things that work, and can be depended on. That includes gravity.
If
gravity will hold something in place when static, then a simple strap to
take
care of the dynamic situation is all you need. And it's cheap!

Steve

My theory is that the least amount of welding the better. It weakens
the material much less and is a whole lot less expensive.

Brian D wrote:
Steve, or an aluminum expert:

In general bends are better than welds (in aluminum) since you don't have
the heat treatment hardening of the tank in the area of bends, but do in the
area of welds. What if the aforementioned lips on the side, the sides, and
bottom, were all made from one sheet that was bent to make the shape. The
end caps would be welded on, as would the lid, but the welded-on lid would
not be carrying the weight. Is there any issue with bends becoming weak?

Brian


"Stephen Baker" wrote in message
...

Brian says:


I've seen tanks made the way you suggested, but with the tank top

oversize

so it extended an additional inch-plus on either side. This was for
suspending the tank by the lip. With all the pounding that a boat goes
through, I feel concern that the top weldment would be prone to fatigue

and

cracking.
OTOH, I do know lots of people do it this way (1/8" sides/bottom,
3/16" top). What do you think?


I'm not exactly fond of that method. As you say, too risky. If you want

to

hang something make up a bracket properly sized, and then all you have to
replace is the bracket if it fails. THat's the same reason why my stereo
system is component rather than "boom-box" style. I don't have to replace
everything coz the turntable dies (yes, I'm that old ;-))

I love things that work, and can be depended on. That includes gravity.

If

gravity will hold something in place when static, then a simple strap to

take

care of the dynamic situation is all you need. And it's cheap!

Steve




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com