PDA

View Full Version : More on Fuel Tanks ...



Morgan's Cloud
07-06-2004, 01:45 PM
Sorry for the length of this but I wanted it to be as understandable as possible..another Donzi detail freak ..

With this 'favorite' topic coming to the surface again I thought it best not to hi-jack someone else's thread to share this info I learned last week.

It seems that someone around here is always (or always about to) replace a tank and this can only be because we hold onto these great little boats for so long or enthusiastically buy them even when they are by most standards considered 'old'.
So it goes without saying that there must be a great amount of experience/info on this topic.

As of two weeks ago I had not heard of the following ...
My fabricator is making 2 new tanks for the St T.
The front tank was foamed in place and even though I was hoping to get away with a new and improved mounting system there is no way to do it otherwise.
I began investigating the availability of two part foam kits here and there are only 2 different types on the shelf.

One dealer (the Clearcote agent) has gallon AND quart kits. The Evercoat agent has only quart kits..

The Clearcote quart kit sells for about $35 the Evercote kit sells for $104 :confused: Well that caught my eye .

Neither could explain the difference. All I can tell you is that the Evercoat kit has the words "closed cell urethane foam" on the labelling.

Well .... a little search on the web revealed that Clearcote does'nt have a web site but they have a contact for their US and worldwide distributor.

A quick introductory e-mail to Paul Smith was answered pronto and the questions ensued.

Anyway , this is what I found out.. the Evercoat product COULD be their own product re-packaged as they do this for many other suppliers in the industry. My supplier here has the " 2 pound " kit.. This must not be used for gas tank installations. I need the " 4 pound " kit .( Something which must be , and has been , ordered).
The 4 pound kit has a different density than the 2 pound and results in a much stronger tank installation. It is also much more resistant to oils and fuel ( and hopefully water) than the 2 pound stuff.

So there you have it. All the info around here on gas tank installation .. but I've yet to come across this . Because of where the front tank is on the St T I'll ever only have one shot at this , so it has to be done right !

And all those years I thought 'foam kits' were just ' foam kits'... :bonk:

Any thoughts ?

Steve

Forrest
07-06-2004, 02:21 PM
Hmmmm . . . I guess that means I had better not use that 7 or 8 cans of Great Stuff I've got laying aroud here. :p

MOP
07-06-2004, 03:36 PM
Foam even closed cell is no longer legal for new construction but is legal for replacement. It to me is still a very good method if done properly. The cavity should be sealed from the bottom only with a limber tube glassed to both the hull and bulkheads to allow water to pass under and not intrude into the cavity. The cavity must be provided with good ventilation and good access to all fittings. Good tank preparation is a must, one of the best prep jobs I have seen and have since duplicated is to use pumas to blast the tank and immediately apply zinc chromate. The idea is to keep in constant motion until full coated with zinc chromate not allowing the aluminum to form any corrosion (aluminum damn near corrodes in front of your eyes). Once a good coating of ZC is completed and thoroughly dried two coats of epoxy tar should then be applied and let to cure, as long as the coatings are not damaged in anyway the tank will not corrode from the outside. Outside corrosion accounts for nearly all tank failures.

Tony
07-06-2004, 07:55 PM
Good info, Steve. I will soon be looking for these materials and appreciate you sharing your research.

Phil, I plan on looking for a local (Mt. Clemens/Detroit) fabricator who will coat an aluminum tank for me. I will take my old tank with me to have an exact replica made.
Plan B would be to use RDS or Florida Marine Tanks, both recommended by several board members.

While the deck is off I will also take the measurements asked for in this old post:
http://www.donzi.net/forums/showthread.php?t=33756&highlight=gas+tank

If I farm the job out on the internet I will have a drawing made, and will post that somewhere as well.

Mr X
07-06-2004, 08:08 PM
I know of SEVERAL boat manufacturers that are foaming in tanks every day. I was not aware it was illegal.

mphatc
07-06-2004, 10:00 PM
I just went thru this . . .

My new tank was etched with an alumijnum etch by Dupont and treated with their primer after which I gave it three coats of a rock hard Epoxy primer from PPG . . . truck equipment supplier. This was left to cure in ther baking sun for 2 weeks, never allowed to get wet. You can't scratch this stuff!

After calculating the volume around the tank accurately, the tank was foamed in place with three separate pours . . I mixed accurately using large mixing buckets from my automotive paint supplier and stirred each mixture with an electric drill stirrer. When done the finished foam expanded to fill the voids as calculated.

Get this accurately and you shouldn't have to trim the foam after pouring and expansion. The foam will only absorb water where it has to be trimmed or cut.

Mario

Rootsy
07-06-2004, 11:28 PM
OOOOOOOOOOOOOOK phil,

you preach FOAM IN THE TANK IT IS THE ONLY WAY but now you say it isn't legal for new installation? if that is so then even replacements SHOULD NOT be foamed in... apparently someone with some engineering knowledge says it is NOT the right way... so what is it... yay or nay? :confused: :confused: :confused: :confused: :confused: :confused: :confused: :confused:

we have enough folks doing this deal that they need to have the truth... this is a serious enough issue that it needs to be THE BEST way... period... all i am saying...

me personally... i would NOT use foam... i am of the pearson / allard / wind / veth camp... but that is just mho :yes:

JR - missing a tooth or two

MOP
07-07-2004, 03:34 AM
I know of SEVERAL boat manufacturers that are foaming in tanks every day. I was not aware it was illegal.

FOAM FOAM FOAM!

Back when the tank issue was being beat around it was said to be illegal by another member, but apparently it must have been erroneous. I being away from that end of the business for a few years believed it.
To me it is still the best method available only topped by built in fiber glass, it adds rigidity to the boat and the best securing anyone could possibly want.
Since the tank issue I get contacted quite a bit on tank installations. In our hard pushed boats I feel it is fool hardy to not to foam the tanks. We have all seen a few wrecked boats, those with foamed in tanks "the tanks stay put" most other strapped and cribbed ones tear away. Several times I have lifted a deck to find a strapped tank adrift, even just foaming the sides a big improvement.
What happened back during the tank issue was commaraderie over ruled proven practice and common sense!

Oh crap I in the dog house again!

MEAN OLD PHIL

rayjay
07-07-2004, 05:37 AM
Okay, I went back and read through the gas tank threads (which is putting it mildly, LOL) which as a relative newbie to rigging boats I am interested in learning all I can. How are tanks rigged in offshore race boats? They must take an incredible pounding, but I'm sure "time" is not one of the critical factors except for how many hours of pounding they will take and not for how many years they will last.

rayjay

Morgan's Cloud
07-07-2004, 10:18 AM
Ahh , Just can't get too much info on this subject .. and you really take it to heart even more if you're about to do a tank replacement :biggrin:

What I wanted to do here was just share the info about different densities of foam and their uses .
Interestingly the Clearcote product (the 2 pound density) has a litany of uses on the side of the package but NO mention of use for fuel tank install ! That does'nt preclude the buyer from believing that it would'nt be just fine for the job though.

I admit .. if there was another way to do the front tank (other than foam it in) I would.However, it does seem that foaming in gives tremendous installation security but compounds corrosion problems.
Anyhow that's why they will be well prepped and coated BEFORE foaming in (all top secret of course).

Phil ... tell me about this "epoxy tar" ... Is it at all similar to the aerosol cans of auto undercoating spray (black tarry stuff)
that you find in hardware/auto shops ?

Steve

MOP
07-07-2004, 10:44 AM
Most any marina will have Epoxy tar on hand or do a search and order some, it is what should be used. I think undercoating is to soft and will over time break down.

Phil

Morgan's Cloud
07-07-2004, 11:41 AM
Man .. this is getting scary ...

I'm begining to think that a sailboat with NO engine is the way to go ! :boat:

Phil .. Is "gluvit" kinda like what you're talking about ?

Steve

MOP
07-07-2004, 04:54 PM
Scot there is a regulation against coating "Ferrous Metal tanks" aluminum is a non ferrous metal. There is also a section stating the foam type. I gleaned the facts from speaking to two tank manufacturers one told me where to do the search, at least this helps to clear up the issues a bit. These are the most current USCG regulations.

Phil

http://frwebgate3.access.gpo.gov/cgi-bin/waisgate.cgi?WAISdocID=2381891258+25+0+0&WAISaction=retrieve

gcarter
07-07-2004, 04:57 PM
DIESEL is the answer!! :jestera: :biggrin: :biggrin: :smile:

George....well, thanks Phil, we can't argue senselessly anymore!!