Replacement Tank Questions

JohnV8r · Post by **JohnV8r** » Feb 22nd, '07, 16:06

I have a couple of questions on replacement fuel tanks.

I took a copy of the line drawing of the fuel tank that Capt. Patrick provided from his work on Gerry Santiago's B31 to my best option here for a replacement tank quote. He asked me if I wanted to go any larger than the 78" inches of length, noting that the cost to build additional length into the tank would be nominal. I have not had an opportunity to go down to Shambala and make any measurements. However, my first question is what is maximum length on a replacement tank (length being the bow to stern measurement) that is generally considered feasible? I would like to have as much tankage as possible without creating any issues.

Second question: When replacing the fiberglass tank, what is the appropriate method for securing the new aluminum tank in place? Do I need to have tabs built on the aluminum tank that will overlap the stringers or can I simply get the tank in place and then glass it in place? Also, will I need to use foam to fill in the gaps on the bottom and sides of the tank? If foam should be used, what is the best method for channeling water below tank? PVC tubes?

Finally, it was recommended to me that the exterior of the new aluminum replacement tank be powder coated to make it more corrosion resistant. When I asked about coatings or linings on the interior of the tank, I was told it was not necessary. Any thoughts on powder coating exterior or the non-treatment of the interior of the tank?

As always, thanks in advance for the feedback.

JohnV8r

In Memory Walter K · Post by **In Memory Walter K** » Feb 24th, '07, 12:32

John-No answers? I'd like that info myself for my B-20. Walter

JohnV8r · Post by **JohnV8r** » Feb 24th, '07, 15:54

Walter,

I haven't heard a thing in response to my questions.

Obviously, the two most critical questions are how best to secure an aluminum tank and whether or not a coating on the interior of the tank is necessary.

If I get something offline, I'll post it.

Thums Up2 · Post by **Thums Up2** » Feb 24th, '07, 16:31

John,

I can't speak for the bertrams but my charter boat in CR had a new aluminum tank put in. It was done here in New Jersey before it left. They used metal straps and glued neoprene to the tank with 5200 where the straps crossed the tank. Also, they coated the tank with truck bed liner. I do know that it isn't much more to make a tank a little longer because we did the same. We add a foot and it was only like 25 bucks more.

lobsta1 · Post by **lobsta1** » Feb 24th, '07, 17:38

John,
two of us B33 owners had new SS tanks made at Nautic. I wanted Nautic Doug to put flanges on my tank so I could fasten yo the bulkhead. Doug said that was a strict NO-NO. The tank would suffer from "oil-canning" & subsequentl metal fatigue. He said to cover the bottom of the tank with undercoater. Put it on non absorbent material & secure the tank with metal padded straps. (Non-absorbent also).

Here is a link showing my install.
http://www.bertram33.com/forum/topic.as ... hichpage=1

Al

Harv · Post by **Harv** » Feb 25th, '07, 15:09

John,

I am in the same situation. I beleive I made a post a while ago about a product called Red Kote. It is an internal liner for metal fuel tanks. I am considering this as ethanol still seems to offer an etching problem for aluminum and this coating is impervious to all fuel additives. Originally saw the product listed on Ebay.

The procedure is to prep the tank and the liner, pour into the tank, cap all openings and then rotate the tank for complete adhesion. Seems like something I would want the tank builder to do as I feel it is easier at the factory than at a boat yard.

As for mountings, I beleive Patrick had mentioned using some type of film to coat the outside of the tank, place in the bilge and fill with the foam. Then pull the tank back out, discard the film and reset in place. This procedure would facilitate easy removal in the future for any reason that should arrise. Use pvc strips on the bottom of the tank to allow for breathing and the flow of bilge water. Most people here feel that the outside of the tank be coated with some sort of liner, whether it be coal tar or truckbed liner as has been used by others.

JohnV8r · Post by **JohnV8r** » Feb 26th, '07, 00:34

Hey Guys,

Thanks for the responses.

Harv - do you remember approximately when it was that Capt. Patrick posted about the foam procedure?

Thanks,

JohnV8r

CaptPatrick · Post by **CaptPatrick** » Feb 26th, '07, 05:33

John,

In the "Tips Section"....

Design and Installation of a Fuel Tank

Br,

Patrick

In Memory Walter K · Post by **In Memory Walter K** » Feb 26th, '07, 10:20

Patrick-What about powder coating? The fabricator offers it on my 50 gallon B-20 Bahia Mar replacement tank. Also, on a tank that sized, is 1/8" aluminum OK? Walter

CaptPatrick · Post by **CaptPatrick** » Feb 26th, '07, 12:10

Walter,

Not being a tank builder, I can't say about the thickness, it's probably OK...

Powder coat would be fine, try to specify Epoxy Power.

Br,

Patrick

JohnV8r · Post by **JohnV8r** » Feb 26th, '07, 13:04

Patrick - Thank you

Walter - The guy I met with that builds fuel tanks for a living told me he would not use anything less than 3/16" aluminum on a fuel tank. I hope that helps.

JohnV8r

PHILRAJOTTE · Post by **PHILRAJOTTE** » Feb 26th, '07, 13:39

YES I WOULD RECCOMMEND TABS FOR SECURING THE TANK TO THE STRINGERS THE TANK THICKNESS SHOULD BE 3/16 NOT 3/8

JohnV8r · Post by **JohnV8r** » Feb 26th, '07, 14:44

Thanks for the correction on the thickness. That was a typo on my part. I have edited my original post.

BillinFI · Post by **BillinFI** » Feb 26th, '07, 21:31

I've just ordered new tanks for my 25. I met at my boat with the salesman from Luthers in RI and he took an old tank back to the factory. Luthers is the major tank builder around here - all the yards recommend them - so I went with them. They'll be putting tabs along the inside edge where the tanks sit along the centerline stringer for holding them in place. He strongly recommended staying away from foaming in the tanks. He did say to epoxy coat the tanks and recommended the Interlux product but I'll use Awlgrip primer, 545, with the aluminum process. He was honest in saying good practice yesterday is now often known as poor practice today and good practice today may prove to be poor practice as well. At least he was honest!
Bill

JohnV8r · Post by **JohnV8r** » Feb 26th, '07, 21:41

I've now read all the information I could find. Al, thanks for the link to the thread on your replacement tank installation on your B33. That thread had links to a ton of great information that helped me decide that I will use Capt. Patrick's foam method for installation.

For everyone's edification, there were links to David Pascoe's thoughts on installation of aluminum tanks, and the Coast Guard's Boating Safety Circular #79 (use of metallic fuel tanks). I read both of those articles and Capt. Patrick's Fuel Tank Design & Installation from the building tips section on the old site.

Here is a quick summary of what I found to be the most interesting points from all three sources:

1. The Coast Guard commissioned a study on aluminum fuel tank failures and found that 92% of aluminum fuel tank failure was from corrosion caused by improper installation.

Improper installation of aluminum fuel tanks could lead to corrosion related failure after only a few years of service.

The main installation issue was installing an untreated or improperly treated aluminum fuel tank in the bilge area or in a manner that would cause the aluminum to be in constant contact with water.

2. Another significant leading cause of aluminum fuel tank failure was improper wall thickness of the aluminum.

Some manufacturers used aluminum with a wall thickness of 0.090", which caused failures due to fatigue cracking at baffle wields. There was speculation that fatigue cracking may have been misdiagnosed as corrosion related failure.

Doubling the wall thickness of aluminum increases the time required for corrosion to perforiate an aluminum tank by a factor of eight.

Using aluminum with a wall thickness of .125" (1/8") significantly reduced the number of corrosion related failures as well as the number of fatigue related failures at the baffle welds. So Walter, you should be way ahead of the game with powder coated 1/8" aluminum on your tank.

3. Another significant source of aluminum fuel tank failure was abrasion.

I found this discussion to be rather enlightening from the standpoint that it seemed to directly contradict David Pascoe's recommended installation methodology. This was because the use of plywood platforms with plastic strips create abrasion points that could destroy a tanks outer treatment, thus leading to crevise corrosion.

By contrast, Capt. Patrick's foam method would not create any abrasion points on the tank. The most critical issue would seem to be making sure you got the foam completely filled in so there are no voids that could collect water. However, even if you have a void, if the tank were properly treated with an exterior coating it would seem you would have years of protection from crevise corrosion. Furthermore, if you follow Capt. Patrick's installation methodology completely and use visquene so you can lift the tank out, you would be able to identify any significant voids when you lifted the tank out. They could then be filled in before you finished the installation.

There was also some discussion of stainless steel tanks that focused on stress corrosion cracking and failure at weld areas.

Capt. Patrick's installation method is linked in his reply above. Here are the links to the other two sources of information mentioned:

http://www.uscgboating.org/recalls/pdfs/BSC79.pdf

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

Based on what I learned, I will have my new aluminum tank powder coated and use Capt. Patrick's foam installation method. I also found great information about how to use/install foam for Capt. Patrick's installation method on the US Composites website. Here is a link to that information on their website:

http://www.shopmaninc.com/faq_foam.html#1

I hope this helps some other people.

JohnV8r

Carl · Post by **Carl** » Feb 27th, '07, 08:22

A few points I can add,

If you do tab, it should only be to restrict movement as the tank should be supported from underneath.

Powdercoat, as with anything if not done properly you may have poor adhesion and/or cracking which can lead to areas that will hold moisture resulting in a situation worse then leaving bare. Bare aluminum immediately builds an oxide layer providing SOME protection.

Rubber and Aluminum should not be in direct contact, it WILL cause corrosion.

I went from a 160-170 gal tank to 220, yes not much more of an expense, but I have found the boat performs quite different, most notable at low cruise with less then a 1/2 tank. All the weight is now aft and makes the planing at low speeds difficult. Point of reference, try to remember when you have had a few big guys sitting on the transom when getting on plane...you will go but you notice the performance a bit sluggish. Put more fuel in and the weight gets distributed better or run harder to flatten out boat and weight again becomes more evenly distributed, tabs may be a benefit now too.

Just a few tidbits to share

Raybo Marine NY · Post by **Raybo Marine NY** » Feb 27th, '07, 09:50

coating and installing a tank is one of those things you can ask 6 people and get 6 different answers.

No offense to anyone intended- but just because someone put thier OPINION on a website does not make it gospel. I am more referencing Pascoe's site that has somehow become a bible for the misinformed.

Absorb all your information, and make a decision based on your findings.

this line that BillinFI quoted says it best:

"good practice yesterday is now often known as poor practice today and good practice today may prove to be poor practice as well"

you remove coated tanks living in a foam free enviroment that have failed in less then 5 years, and you see perfectly good 10+ year old tanks sitting in foam uncoated.

Carl · Post by **Carl** » Feb 27th, '07, 10:58

Raybo, you are 100% correct, ask a dozen people a question and get 13 different answers.

That is what I find great about this site, you get all the answers, theories information and misinformation and then get to make up your own mind. State something incorrect here and someone with more knowledge will rebutt your info and may even tell you why, what is better then that. IF they don't tell you why you can at least go look for the info yourself and can't look back a year or two later and say... I didn't know or I never heard that.

Matt29 · Post by **Matt29** » Apr 26th, '07, 11:20

Can anyone elaborate on the comment by 'Sim' about Rubber and Aluminum resulting in corrosion when in contact? Many of the local tank builders around by me powder coat the tanks and then put rubber strips on the bottom of the tank. I was intending on using 5200 to apply the rubber strips. Is the corrosion concern invalid if the aluminum is powder coated or should I coat with the Devtar5A over the powder coat and then apply the rubber? As always, the input of this board is greatly appreciated.

Thanks,
Matt

John C · Post by **John C** » Apr 26th, '07, 18:01

rubber has carbon in it which will eat through the tank. Use neopreme strips under the tank

Harv · Post by **Harv** » Apr 26th, '07, 19:35

However, my first question is what is maximum length on a replacement tank (length being the bow to stern measurement) that is generally considered feasible? I would like to have as much tankage as possible without creating any issues.

John,

I lifted the deck 2 weeks ago and took rough measurements of my 170 gal tank.
The length of my tank is 78 inches.
The width is 34 inches.
The height is 21 inches.

From what I could tell, I could probably gain 3 more inches in length and stop just in front of the bilge pump mount. I could also increase the height of the tank by almost 2 1/2 or 3 inches.

The line drawing for Gerry Santiago's tank (approx. 230 gals) measure
78 in length
33 in width and
24 in height

I have opted to go with Richard Kidd's (High Tide Marine is selling these same tanks) new fiberglass design (also rated at approx 230 gals). That design measures
78 1/2 in length
33 1/4 in width and
22 1/2 in height

There is some slight difference in measurements at the bottom of the 2 tanks, but other than that they are pretty close in external dimensions.

The reason I opted for fiberglas is because .........
Fire Resistant Class I Resin
100% Ethanol resistant
Improved resistance to hydrocarbon solvents and oxidizing media
Deforming point over 280Âº
Fiberglass Baffles
Five year guarantee

No external coating or strips needed to be placed to space the tank from the hull. All fittings are in the original stock locations. No welds or corrosion to worry about. It's about twice the price of aluminum, but hopefully this is the new "forever" tank.
You can view the information at High Tide's webpage

http://www.hightidemarine.cc/fuel-tanks.htm

I am choosing Richard Kidd over High Tide because Richard is a site sponsor.

thereheis · Post by **thereheis** » Apr 27th, '07, 21:04

hey harv what kind of price are they gettin on the 230 gal. tank ???

phil

Harv · Post by **Harv** » May 3rd, '07, 22:00

Asking price was $4800 plus $300 shipping to my location. Since I work for one of the big carriers, I looked into our employee pricing and will only be paying $120 to ship from Miami to Long Island, NY. The measurements look good for a perfect drop in. The only thing I might have to do is change the backing for my fighting chair and cut down the bolts by about 1/2 to 1 inch. Right now there is a 2 inch thick piece of wood which I will probably replace with 1/2 inch aluminum.

Doug Crowther · Post by **Doug Crowther** » May 8th, '07, 09:18

Harv,
Even a 1/2 inch aluminium backing plate sounds obscene. I didn't have much room @ all on my 1977. The backing plat that came with the Murray Bros chair wasn't even 3/8 thick and there is absolutely no flex.

Harv · Post by **Harv** » May 8th, '07, 21:42

Doug,

I was just going by the amount of clearence I anticipate on having. If you say 3/8 will sufice then that is what I will use. The shipping price was very deceptive. For $120 I would need Richard to drop off the tank at the terminal near him, and I would have to transport it from my terminal to the boatyard. Looks like I will have the competition carry the tank from Richard to my boatyard. Boy is this some way for a company to treat their employees or what? Sheeeeesh!!

bertram31.com

Replacement Tank Questions

Replacement Tank Questions

TANK REPLACMENT

Tanks

no rubber

fuel tank

Who is online