How to re-attach fuel tank internal baffle

[model 10]

I guess that unless you have spent untold hours removing fuel tank sealant from surfaces, you could never know how tough it is. It's a **** job but somebody has to do it.

[Tayana42]

Is there a reason he couldn’t use safety foam baffling like Aero Tech uses in its flexible tanks instead of the solid baffles?

[AKA-None]

Originally Posted by Tayana42

Is there a reason he couldn’t use safety foam baffling like Aero Tech uses in its flexible tanks instead of the solid baffles?

This would be simpler and works well in fuel cells

[stainless guy]

In place repair if you were to weld

Steam clean as most welders will stray away from welding inside a fuel vessel

Not a diy job unfortunately the best place to find a proficient welder is a shop that does recertification or manufacture of highway tankers as they do this sort of thing all the time is there enough room in the tank to climb inside? 16x16 entrance and an area of about a cubic meter to work in is close to the minimum

You can help them by cleaning the areas that need welding with a die grinder and "non ferrrous" die grinder bit as they will not contaminate the basemetal, clean down to shiny metal. Fit the piece back in the location it needs to be in and call in the welder

If the panel has alot of flex add a couple of stiffeners in the form of 1.5" x .188" angle or square tube to help stop it from happening again

Mechanical fastening of baffles works but you would still need to weld tabs on the inside of the tank wall to fasten the baffle to, or some sort of adhesive.

All that said weigh what the repair will cost in a few different ways

-Steam cleaning will be required for any method Imo
- if someone were to call me for a job such as this I would say to allow minimum 10hrs to do everything
- maybe look at ripping out the other baffles and install bladder tanks inside the shell of the old tank?

[jimbunyard]

Originally Posted by stainless guy

...Mechanical fastening of baffles works but you would still need to weld tabs on the inside of the tank wall to fasten the baffle to, or some sort of adhesive...

Not trying to cut anyone out of a job or a sale, and anyone who can afford a Catana 47 might not need to worry about 'small costs', but the 'B' solution shown earlier offers a fix without gluing, cleaning, welding or ripping out and replacing tanks.

Based on a tank 2' D x 3' W x 4' L= 177 gal (that I could find the 47 has a 148 gal tank)

From Home Depot, 2 - 3/4" x 1/8" x 96" aluminum angle, 20.00 each, 10 - #10x24 stainless machine screws with locknuts, 10.00 total = 50.00 materials.

2 hours to cut, bend, drill and install the frames, 3 if I dick around,
3 X 40 (neither bonded, insured or otherwise official) = 120.00

Total less than 200.00, but easily a DIY project with a hacksaw, drill, 3/8" nutdriver or wrench and a Philips head screwdriver.

No gluing or welding is necessary as I'll try and explain one more time; avoiding those two options is specifically what I was getting at in my original and subsequent post.

[grahamb]

another thought......at one time I had a slight involvement with the Formula 1 industry...….there was a product that I could describe as 'scrim'......i.e. metal shavings such as a lathe produces.....the petrol tank was filled with this material (better than the rough description above) and eliminated surge.....and …..if the tank was ruptured...only allowed a small flame on the surface......maybe still around....(rather like a metal pot scouring pad material)

but...….the aluminium fins as used as part of air conditioning and refrigeration condensors/evaporators would seem to me to be ideal.....could be obtained from a heat exchanger manufacturer new and clean......are riddled with holes …. where the copper tubes would ordinarily go.....can be cut to size with scissors....to the exact internal tank size ….. and only an extremely small loss of fuel fill capacity would occur...……and should be cheap too...……..

[stainless guy]

The bitterness of poor quality will outlive the sweetness of price.

Also I did not comment on your suggestion because it is not a good one,
you know if you don't have nice things to say .. Bubba comes to mind

Not trying to sell but the right path is likely the most difficult

[grahamb]

found it...…….search...…..fuel tank explosion protection...…..you tube...…

[jimbunyard]

Originally Posted by stainless guy

The bitterness of poor quality will outlive the sweetness of price.

Also I did not comment on your suggestion because it is not a good one,
you know if you don't have nice things to say .. Bubba comes to mind

Not trying to sell but the right path is likely the most difficult

Price is nothing to do with it.

For my education, please explain why it's a bad idea. Oftentimes the simplest solution is the best, especially when the evidence for other solutions being less than ideal is evident.

Don't mention things like non-rigidity of baffles or frames, or them moving around wearing holes in the tank sides because if done properly those things can't happen. (Just for fun I left one potential, and unanswerable, negative out)

A baffle system completely assembled in the tank and not attached to any exterior walls is easily imagined, and would likely be cheaper than (or if it's easier on delicate ears, less expensive than) welding in new baffles or installing new tanks, be they rigid or flexible, or filling the tank with some kind of 'slosh resistant' material (believe this is a diesel tank--what happens when biocontaminants invade? [not being facetious]). That leaves glue, since I'm a natural sceptic, I'd worry about the longevity of a bond made on a previously filled tank. But glue at least has the advantage, along with the frame or removeable baffle idea, of being easily accomplished, verified and modified if necessary.


Wondering who Bubba actually is, if I understand your drift correctly.

[Pete7]

How much work is actually involved in removing the fuel tank? because then you can take it somewhere and get it done properly. As Thinwater said, if one weld has gone I would want the others inspected before putting it back and filling it with diesel.

Pete

[Jetx]

Thanks to everyone for the excellent and thoughtful suggestions. Very much appreciated!

The tank can't be removed without cutting it in pieces or cutting through the deck. There's also no access to sides or bottom of tank, so I'm resigned to doing what I can through the the roughly 12" x 18" top inspection port.

Another owner reports having accomplished this exact same repair using nothing but g-flex (and having it hold for many years + thousands of miles). Based on that report, and discussion above, I'm going to try epoxying angle to the inside wall, bolt the baffle to that, and then use angle+bolts to join where the two baffles meet.

Thanks again.

[BatEng]

Jetx,
I was going to expand on the fuel tank sealing method and let you know that stuff, when applied correctly, is very strong and flexible. (I suspect that Ecos and I have done some similar work in past lives). Sounds like you are moving forward with the G-Flex option. I will just say, regardless of the epoxy or sealant, preparation of the surface is the key to a long lasting bond. Clean using the manufactures suggested solvent, make sure the surface is roughed up a little bit so it can bite and don't overwork or rush the curing process.
If you do decide the aircraft fuel sealant is the way to go. I suggest getting the 2 hr work time stuff since you have never used it before. it takes longer to cure (up to 72 hours depending on heat and humidity) but you will have plenty of time to get it worked correctly and smooth edges to help keep fuel from getting underneath overtime. Also, make sure you get an adhesion promoter. it really helps bond the sealant to the surface.
Good Luck

[Cadence]

Shame on me. Liquid Nails, doesn't sound salty but I've had it bond to aluminum for over 30 years. I would check on exposer to diesel but that might be on the tube or a web site.

[utopf]

This tank has probably been fixed by now, so my comment might not be terribly useful but I am giving my two bits for other readers who may be reading the thread.
The aluminum diesel tank on my 1982 Saturna 33 last summer slowly started leaking into the bilge - I believe it was caused by "Poultice corrosion". After a fair amount of research which lead me to other blogs, I see that aluminum tanks are NOT being installed in modern boats any more because they are susceptible to Poultice and other corrosion: Marginal Maritime Advice: Poultice Corrosion
My tank is quite oddly shaped and is 50% located under the dinette. This is all I could expose after removing some cabin sole and two athwardship stringers. I am attaching some pictures of dealing with my problem - including a close-up of corrosion pits in the inside of the bottom of the tank. Anyway, first, I pumped out about 110 litres of diesel through the dipstick opening. Then I cut up the top of half the tank and associated baffles with a 4 1/2" angle grinder with metal cutting discs - a very tough job - the aluminum was 1/8" thick....By the way, the baffles in my tank would never have come loose - they were extremely well welded in place - even with plug welds to the top plate !
Based on calculations with the dimensions of the tank it held 150 litres (theoretically), which is way more for what I need for my coastal cruising in BC. (My 3 cylinder Yanmar burns about 2.5l /hr for 5.2 knots at 2200rpm).
Therefore I have decided to place a new 85 litre tank inside the old tank. We can always take some Jerry cans onboard for an extended trip..... Unfortunately, none of the tanks listed in the catalogues by MOELLER or SAINTmarine - none big enough will fit inside. I am now investigating if I can get a custom made plastic tank by TekTank (https://www.tek-tanks.com/order-process)- they are located in the UK.
If shipping from the UK turns out to be too expensive and/or takes too long, I will build my own out of plywood coated with fiberglass and (inside) epoxy. I will let you know what I ended up with...........
I read that a lot of people are shying away from fiberglass tanks because fiberglass is being attacked by the ethanol added which is now standard 10% in GASOLINE. As much I can see, any diesel fuel does not (and probably will not in the future) contain ethanol. Epoxy is definitely resistant to ethanol. Expensive and reputable power boats such as Fleming, Bertram etc and Beneteau have built-in fiberglass tanks for diesel.

Anyway my advice to the original poster on this blog would have been to gut the existing aluminum tank and do what I plan to do, because ALL aluminum tanks leak/fail sooner or later .