aluminum fuel tanks

[J.M.]

I'm having new fuel tanks made for my salty dog, has anyone had any experience with coating  them? I am having people suggest coating them with truck bed liner to protect  them from moisture being trapped which looks like why the old ones failed. The old ones had 2x2 cleats holding them in place, this is where most of the corrosion was happening. thanks for any advice. John

[David Oates]

John,

 

I have no experience with this, but it sounds like a good idea! I have often heard about corrosion where the tanks sit.

 

David O

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From: J.M. <nor...@gmail.com>
To: unifli...@googlegroups.com
Sent: Wed, June 20, 2012 4:34:40 PM
Subject: [UnifliteWorld] aluminum fuel tanks

I'm having new fuel tanks made for my salty dog, has anyone had any experience with coating  them? I am having people suggest coating them with truck bed liner to protect  them from moisture being trapped which looks like why the old ones failed. The old ones had 2x2 cleats holding them in place, this is where most of the corrosion was happening. thanks for any advice. John

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[e b]

how old were the tanks, if they were original and lasted 40 years do you think you really need to coat them.... good bedding compoud where the cleats were were should be enough to take care of preventing trapped moisture, they will last 60 years then..

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Date: Wed, 20 Jun 2012 16:34:35 -0700
From: nor...@gmail.com
To: unifli...@googlegroups.com

Subject: [UnifliteWorld] aluminum fuel tanks

I'm having new fuel tanks made for my salty dog, has anyone had any experience with coating  them? I am having people suggest coating them with truck bed liner to protect  them from moisture being trapped which looks like why the old ones failed. The old ones had 2x2 cleats holding them in place, this is where most of the corrosion was happening. thanks for any advice. John

[John Miller]

The tags on the tanks say they were built in 1997, and there are dime sized holes.Looks like the installer tried to shim them up with rubber hose but on the outside of both  you can see the corrosion is where the moisture is trapped. 

[Russell Davignon]

FYI

 

They used to try to protect the old black iron tanks by encasing them in fiber glass but all it did was trap water.  They also tried undercoating cars wirth some rubbber spray up North but the rubber eventually cracked and trapped water.  BOTH actually enchanced rust or corrosion. 

 Aluminum boats are NOT coated with anything topsides ( If the owner has half a brain paint  for looks is fine but then you have paint to maitain).  Any good aluminum boat owner leaves them as is and lets the aluminum develop its own protective oxidation layer. 

 

Whatever youu do remeber dissimilar metals wil casuse a battery reaction!!!!!!!   Russ

 

PS  If you want the real answer contact the Metal Boat Association and some one knowledgeable wll respond.

 

 

 

 

Be Holy or Die Trying"  St Stephen 33AD

"Be joyful always; Pray constantly; Give thanks in all circumstances, for this is God’s will for you in Christ.....Test everything. Hold on to what is good. 1 Thessalonians 5:16

"Since you cannot do good to all, you are to pay special attention to those who, by the accidents of time, or place, or circumstances, are brought into closer connection with you." St Augustine

From: J.M. <nor...@gmail.com>
To: unifli...@googlegroups.com

Sent: Wednesday, June 20, 2012 7:34 PM

Subject: [UnifliteWorld] aluminum fuel tanks

[John Miller]

thanks for all the info, my fear was if the coating did not stick to the aluminum it would cause  much more harm than good, and looking at the old tanks all the corrosion is where the insulation and the wood cleats(with no bedding compound) collected moisture.
also the tanks had the original bonding wires(40 years old, good guess!) probably had to do with the problem. thanks, John

[Jerry Legate]

Check out the link below.

 

http://www.yachtsurvey.com/fueltank.htm

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[John Ellison]

Excellent article......

___________________________________________________ 

"Hang in There"      "Dont be the guy in the station wagon......."

[John Strong]

I agree, that's a good web page.  David Pascoe has written some good stuff over the years.

I'm also a surveyor, and I look at a lot of fuel systems.  I think the most important item regarding installation of an aluminum fuel tank is air circulation.  If the tank is made of the right marine-grade aluminum alloy, it doesn't need painting if it has good circulation under and around it.  Whatever is used to support the tank off its shelf must be non-absorbent and present no risk of galvanic action.  Note that David says don't use rubber because it contains carbon-black, but there are closed-cell (non-absorbent) foam products that will work. 

I had a '72 Salty Dog that I re-tanked, and I found strips of closed-cell foam, with pressure-sensitive adhesive on both sides, at a supplier in the commercial glass business. 

http://www.atlassupply.com/

The strip product is used to fuse two layers of glass together at the edges in the production of thermal insulated windows.  It's neat stuff, and not too expensive.  It's about 1" wide and 1/2" thick, with adhesive on both sides.  I positioned strips of it across each tank bottom, directly under the baffles inside the tank.  The tanks fit tightly under the cockpit deck on the Salty dog; I secured them using pieces of 3x3" aluminum angle screwed to the undersides of the cockpit deck.  Don't put a strip of wood around the base of the tank to secure it - that will trap moisture!  If your old tanks were installed in '97, that's only 15 years - those tanks were installed wrong.

You said you're having tanks made - remember that federal law requires the tanks to be built by a shop that knows how to pressure-test and properly label the tanks.  And, because they're a very tight fit, it's easier to install the tanks if they don't have welded spuds for attaching the fill and vent hoses.  Have them built with threaded fittings welded flush  with the tank tops and then install stainless steel nipples after the tanks are in place.  I had my tanks built by Coastline Equipment in Bellingham, WA - they built the original tanks for Uniflite, and they still have the drawings on file.  They weren't too expensive, and they fit like a glove.  I'm in Seattle, so I picked the tanks up at the factory.

http://coastline-tanks.com/ 

And, also remember that the feed lines from the tanks to the engines must contain check valves at the tanks - again, required by law, as well as ABYC standards, to prevent a siphon in the event of a leak.  And, the law also requires a very specific type of fuel hose that must be labeled," USCG A-1"  Don't scrimp on fittings or hose - replace everything all the way to the engines while replacing the tanks, including fill and vent hoses.  

There's more to consider if you want the installation to comply with ABYC standards, which hardly existed when Uniflite was in business.  If you have more questions or concerns, maybe I can help.  This user group is a good place to discuss this stuff, since everybody who loves these tough old boats can benefit by knowing how to safely update them.

John Strong

stron...@yachtexpert.com

1981 37' Coastal Cruiser "SURPRISE"

[Den]

On Wednesday, June 20, 2012 4:34:35 PM UTC-7, J.M. wrote:

I'm having new fuel tanks made for my salty dog, has anyone had any experience with coating  them?

 

   Yes I have used POR 15 to coat the inside of 2 200, and 2 100 gallon tanks. The cost of replacing them was astronomical. I removed them, cut several large ports in the tpo, and scrubbed out 1 to 1/4 inch of gunk with diesel, then soap and water. I tool them around the corner to a sandblaster, and let them have at it. Got them back all nice and shiny inside and out. Time to wash out residual sand, and dry. POR 15 requires etching with their prep. Then application. Second app has to be before drying, as NOTHING sticks to it after setup. There were pinholes that are nit there anymore. Tanks are sitting on 1/2 X 4" rubber strips..I transferred 180 gallons of saved / scrubbed fuel into the worst tank (starboard) and dry as popcorn for 2 years, so far. Project can be viewed at densnet.net. Sorry this turned into such a long dissertation, I am over 70, and talk too much.
Den 48YF
.