1978 gb 32 fuel tanks

[Woody5]

Will the diesel fuel tanks on a 1978 GB 32 be trust worthy with a pressure test and a visual inspection or are the so old that they should be replaced at this time?

 

[Marco Flamingo]

I don’t think either test will tell you much. Certainly won’t tell you how soon a tank will fail. A visual test by installing inspection ports would allow one to actually clean out the tank and see the extent of the corrosion. Unless the tank bottom was absolutely perfect, I would line them as a matter of course. Our local business that does this charges about $2K per tank. I haven’t heard any stories about epoxy liners failing, but removing the engine(s) to access tanks and replace, cutting holes in the side of the boat, cutting tanks out and replacing them with a series of little tanks, seems to be more popular. Don’t know why. Search Trawler Forum for “Splash Zone” for info.

 

[Comodave]

I haven’t been in a GB32 but I assume it is a single engine so there should be room to easily cut up the old tanks and pit in new tanks. Not a terrible job but could be dirty. I would not pressure test that old of a tank because if it isn’t leaking now it likely will be after the test. Adding inspection ports to that old of a tank is probably throwing good money after bad. Visually check out the tanks as good as possible. If they look ok then live with them until they eventually leak. If they look bad then get a discount for the replacement cost.

 

[slowgoesit]

Not just the inside of the tanks you need to worry about, check out the top, especially near the fuel fill pipe. Teak decks of that vintage tended to leak either at the fill point, or from poorly maintained deck joints/fastener plugs.

 

[O C Diver]

Regarding a pressure test, a fuel tank for an inspected vessel is pressurized somewhere between 3 and 6 PSI. It's built to a significantly higher standard. This is done with water, not air. I had a new tank built for my charter boat and only pressurized it to about 2 PSI to check the welds with soapy water. While a visual inspection may relieve your concerns about pitting, it won't tell you anything about the welds.

I would get an estimate to replace the tanks if you can't do it yourself. Then decide whether to do it, coat them, or let sleeping dogs lie.

Ted

 

[CharlieO.]

You could do a pressure test, that'll tell you it holds pressure at that moment in time. Are you talking during pre-purchase inspection or post-purchase?

I cut out my old tanks and replaced with smaller plastic ones. No regrets, everything is new the deck fill, tanks, fuel lines and valves.

Having already been through this, on our next boat if still equipped with original tanks I will opt for cutting in access ports so I can clean and visually inspect the tanks from the inside. If it looks bad, I'll keep cutting and remove, if it looks good, I'll apply some sort of liner/sealer. My tanks were very solid and had one small drip on a weld seam on the low point on the bottom and one was rusted around the deck fill on top. I think they would have been a good candidate for repair in place.

If you do end up doing a pressure test, please follow up here. I'd be interested in the method and results.

 

[PM]

If they have not been repaired or replaced, they are ready to go. You are basically living on borrowed time.

pete

 

[mvweebles]

If they have not been repaired or replaced, they are ready to go. You are basically living on borrowed time.

pete

Why? If the decks have not leaked and fuel well tended, steel tanks should last almost indefinitely, no?

Peter

 

[jungpeter]

Why? If the decks have not leaked and fuel well tended, steel tanks should last almost indefinitely, no?

Peter

Hi Peter. We'll have to agree to disagree on the fuel tank longevity issue. In my experience(s), fuel tanks have a finite lifespan, with 20 years being a realistic life expectancy. Anything longer is a pipe dream, and if your boat's tankage exceeds that "use by" date, you're on borrowed time, no matter how well tended they may be. There are, of course, unicorns for first class OEM manufacture, installation, and one-owner diligent maintenance and care. Personally, I've never been able to afford a unicorn.

My opinion, of course, tempered by decades of boat ownership, and multiple tank replacements in various vessels along the way.

Regards,

Pete

 

[jungpeter]

Will the diesel fuel tanks on a 1978 GB 32 be trust worthy with a pressure test and a visual inspection or are the so old that they should be replaced at this time?

Hi Woody5. In-situ pressure testing of fuel tankage is not considered standard practice for quality assurance, or a norm for survey. Pre-delivery of replacement (or OEM) tankage is routinely performed, when you can actually FIND leaks and potentially repair them prior to installation. Once they're installed, you're stuck with visual inspection, particularly for a condition survey pre-purchase.

In my opinion, service life of all marine tankage for recreational powerboats is 20 years. Anything older is on borrowed time.

Regards,

Pete

 

[Comodave]

A lot depends on the installation. If it is under leaky teak decks, especially if the bedding on the filler isn’t maintained, then they can rust. If they are installed with hydroscopic materials and kept wet they can rust. If you let water sit inside them they can rust. But if they were well installed then they should go at least 20 years. 30 is on the outside of the envelope. Our last boat had steel tanks. They looked good but I was going to replace them as a preventative maintenance item, but my back went out. The boat was a 1987 model. The new owner said they started leaking within a year of me selling it to him, unfortunately. So in my experience 30 years and you are pushing it.

 

[mvweebles]

All I can say is my tanks are original 1970 and developed a small leak 2 years ago due to leaking decks. Most of the tank looked fine. In absence of water, I don't know why a tank would leak.....ever (hyperbole, but you get the idea).

Definitely inspect tanks as they are a frequent problem area. But in the absence of problems, they have a very long life span.

Peter

 

[SteveK]

IMO the age does not determine failure. It is water eroding the tank at the top or from inside. For that to happen prevention was not practiced by previous owners.

 

[jungpeter]

IMO the age does not determine failure. It is water eroding the tank at the top or from inside. For that to happen prevention was not practiced by previous owners.

Hi SteveK. Right you are, to a degree! Referring back to the original poster's (OP) question, it is unlikely he has ANY knowledge of the previous owner(s) proclivities to actively maintain the fuel tanks aboard the boat in question. So unless he's REAL lucky and stumbles upon that unicorn of both a vessel with tankage "properly" installed by the OEM (and IMHO a 1978 GB32 ain't one of 'em), and a single owner that recognizes that likelihood and mitigates that fatal flaw by aggressively and continuously monitoring and inspecting his tankage (including adding multiple inspection ports, routine use of same, and diligent mitigation of likely deck leaks) from birth, the OP is only left with intuition and visual external inspection regarding the health of a now 44-year fuel tank.

Again, IMHO, such tankage is REAL suspect. Age, and all that implies (multiple owners, poor initial install, etc.) moves the likelihood of failure well toward the 100% side of this equation.

Regards,

Pete

 

[Xlantic]

My tanks are almost 50 years old and do not leak. They are clean and show no sign of rust either at the top of the tanks (a common trouble-spot from deck leaks, particularly around the fill pipe) nor anywhere else, including the base where it rests on wooden supports.

Six years ago I sold my previous boat, a 1979 GB 42 (over 37 years old at the time of sale) and the tanks were fine as well.

In the GB 42 I installed inspection ports but they were of limited value given the extensive baffling in the tanks.

Besides leaks from the deck and prolonged moisture at the base it is important that there is no water inside the tanks. For this you need a tap at the lowest point in the tanks and periodically take a sample. I did not have such a tap in the previous GB42 but I do in the current GB50.

 

[Woody5]

To prevent diesel tank problems is the correct action to keep tanks as full as possible all the time?

 

[SteveK]

To prevent diesel tank problems is the correct action to keep tanks as full as possible all the time?

That is an often quoted and also a supposed myth. The GB tanks I had drew from the very bottom on the outside (no longer allowed I understand). Since they were bottom draw any water would go into the Racor filter.
There are threads on additives, some just to eliminate what would grow in water, and some to eliminate it.
There is also fuel polishing.
The newer tanks with intake from the top with a tube to near bottom and may not draw up all sediment and water, but the newer tanks may not be steel either.

 

[tomdove]

I have the same boat, a 1977 GB 32 and have gone the rounds with fuel tanks.
A bit of history first: The boat had a major restoration in 2001 that included a new American Diesel and new fuel tanks. I presume from that the old tanks needed replacement because it is not a trivial job. The restorer replaced the single 100 gallon tanks with two 50 gallon ones on each side, piped together. I think this was because he had to cut out the original tanks to remove them and couldn't fit a single large tank back in.

It was a good arrangement with proper valves and all, BUT he neglected to put a spacer layer underneath the new tanks to separate them from the plywood base and allow air to circulate. I was warned about this by the surveyor but foolishly put off correcting it, as it was not an easy fix.

The result was that poultice corrosion built on the bottom of one tank and it leaked. A small and invisible deck leak near the filler allowed water to accumulate on the plywood under the tanks. Last summer was ruined by having to pull the boat, clean the bilge and replace the starboard two tanks (with a proper spacer underneath). Kent Narrows Yacht Yard did the job well but it took over two months simply to get the replacement tanks made. The total cost with labor, haulout and tanks was about $4K as I recall. It was a tight fit even with the 50 gallon tanks and putting in a single 100 gallon tank would have been impossible.

The port side tanks are fine and I cannot find any deck leaks that might cause the same problem.

So the short answer is: The 1978 tanks on your boat are either bad or will be in a short time. If you are negotiating, allow $8K at least for replacing them on both sides and allow a couple of months to get the job done. It's beyond DIY for most of us.

Sorry to bring bad news but that's how I see it.

-- Tom Dove

 

[dutch-barge]

Hi Peter. We'll have to agree to disagree on the fuel tank longevity issue. In my experience(s), fuel tanks have a finite lifespan, with 20 years being a realistic life expectancy. Anything longer is a pipe dream, and if your boat's tankage exceeds that "use by" date, you're on borrowed time, no matter how well tended they may be. There are, of course, unicorns for first class OEM manufacture, installation, and one-owner diligent maintenance and care. Personally, I've never been able to afford a unicorn.

My opinion, of course, tempered by decades of boat ownership, and multiple tank replacements in various vessels along the way.

Regards,

Pete

So my 70 year old fuel tanks, on my 93 yr old steel boat have lived over 3 life times???

 

[jungpeter]

So my 70 year old fuel tanks, on my 93 yr old steel boat have lived over 3 life times???

Yup. There are outliers in any data set. Lucky you.

Regards,

Pete

 

[dutch-barge]

Yup. There are outliers in any data set. Lucky you.

Regards,

Pete

Sorry Pete, not an outlier, I know of many "old". barges/boats who have our age or older and still have the original tanks in them.

Dutch Barge Association. ( barges.org)

 

[mvweebles]

Yup. There are outliers in any data set. Lucky you.



Regards,



Pete

Why would a tank that is properly installed and maintained (meaning no standing surface water) rust out? The average age of registered cars in the US is 12.2 years, all of which have steel gas tanks. Are they 90-months from needing replacement? My camper van is built on a 2000 Ford E150 chassis. Am I on borrowed time?

Just curious about your very definitive statement.

Peter

 

[Tator]

Current boat 44 years on tanks and looking good. Previous boat now has 50 years and doing fine. Just my experience.

Tator

 

[jungpeter]

Oh my. I can see where THIS thread is headed. Right down the wormhole of "which anchor is best", "two engines vs. one", etc. usually accompanied by strongly held opinions based on personal anecdotes, with a sample size of one.

In the context of the original posting, where Woody5 posed the question of the likelihood of 44-year old GB32 fuel tanks being sound, each of my several responses along the way were provided solely as a note of caution to Woody5 that there are LOTS of reasons why that answer is most likely "no".

Along the way in this discussion, I postulated that properly designed, properly installed, and properly maintained by every owner from launch marine fuel tankage can and does last many, many years. Take away any of those provisions, and the lifespan becomes ever shorter. How short? How short's a rope? What's YOUR tolerance for risk?

Personally, as I do not have a functioning crystal ball, my take on fuel tanks for the sorts of recreational powerboats that I evaluate for my own use leads me to view tankage of all kinds with considerable jaundice and suspicion, given NONE of the boats I've owned and operated over decades has had that triad of design, installation, or maintenance that pushes the "use by" date past my 20-year rule of thumb. Has that rule of thumb precluded me from ownership of older boats? No, not in the slightest It HAS precluded me from buying boats that have suspect tankage, and I've learned enough through the years to recognize the same.

As with most things in this lifestyle, there are no absolutes or universal truisms; ALL boats are a compromise, your mileage may vary, and you pays your money and makes your choice.

Not sure I have much more to offer.

Regards,

Pete

 

[jungpeter]

Why would a tank that is properly installed and maintained (meaning no standing surface water) rust out? The average age of registered cars in the US is 12.2 years, all of which have steel gas tanks. Are they 90-months from needing replacement? My camper van is built on a 2000 Ford E150 chassis. Am I on borrowed time?

Just curious about your very definitive statement.

Peter

Hi Peter. Sticking to a boating thread...

Regarding your perception of a "...definitive statement" (presumably about my rule of thumb of a 20-year life for marine tankage), I'll attempt to be brief here. In my opinion, there are three markers of longevity for tankage: original design, installation, and maintenance. If any of that triad is compromised, the useful life of the tankage goes down. So:

Design: Sound design principles, particularly in volume production, include items such as volume, shape, material, fabrication techniques, and pre-installation quality assurance. Poor material choice, fabrication compromises, poor QA, lack of inspection ports, baffle choices, etc. can doom the tankage to an early failure. Jamming the tankage against the deck, thus precluding routine inspection, or stuffing it under furniture and behind bulkheads or outboard of the engines in a twin installation, etc. can doom the tankage.

Installation: Tankage location within the hull, bedding, ventilation, access to the tankage for inspection and maintenance, valving, etc. are all issues the original boat builder must accommodate in their manufacturing process. Many powerboat manufacturers hide tankage behind sound deadening, precluding access to inspection ports, even if the tank manufacturer provided them in the first place. And in general, my major rant-NO production boat manufacturer provides for post-delivery repair or replacement of tankage (or engines, for that matter) via soft patches in the overhead.

Maintenance: If the design or installation of tankage is poor, maintenance is either absent or unlikely. And absent routine maintenance, including periodic sump drainage (oops, few boats even HAVE drainable sumps), removal of ports for internal cleaning and/or inspection (oops, few boats even HAVE tank hatches), external inspection of water intrusion via deck leaks (oops, most tankage installations preclude ANY external inspection capability) damage from such as water in the fuel can occur, with no knowledge aforethought. Just because you can't see it, doesn't mean your tankage isn't going back to Mother Nature.

So, how did I distill this information into my "20-year life" statement? I will be the very first to admit I've not been on every boat built. I've not worked for every manufacturer. I'm not a trained and educated naval architect. There's LOTS of things I am not. However, I have been in this "boating gig" as an owner, builder, operator, maintainer, inspector, designer, for decades, and my family as well, going back generations. I have distilled those experiences to make my own conclusion(s). They are strictly my own, and should other's personal experiences provide other paradigms, KUHL.

I know this short drivel is in no way definitive. There is no way to quantify life expectancy of marine tankage. Aircraft manufacturers come pretty close on aircraft parts with some very complicated failure analyses and replacement guidelines, and even CAT has put forth end-of-life expectancies of their diesel engines via gallons of fuel consumed. So your guess is as good as mine, my crystal ball is as good as the next guys, and your mileage may vary.

Regards,

Pete

ps-not to stir this pot further, but in my opinion, much of the postings on this forum requesting guidance on subjective topics (what kind of a boat should I buy, which anchor is best, two engines vs one, how long do fuel tanks last etc.) result in anecdotal postings to the contrary of whatever is postulated, mostly for affirmation of choices already made.

 

[Tator]

Can't disagree with any of your comments on installation, design and maintenance. I guess I've been lucky that all three of my boats spanning the past 30 years have for the most part met all of your criteria. The one lacking on all three was a drainable sump. I do dip my tanks on a yearly basis with a paste used for home heating tanks that will indicate the presence of water and will also show me any crud on the bottom of the tank-a drainable sump would be better. I do fill my tanks from a source that keeps a 300+fishing fleet going year around and have never had any indication of water on the paste or in my Racors.

I personally find first hand experiences in similar operating conditions helpful in making decisions and is why I offer mine. I have a good friend who operates a 100+ year fishing boat out of my port in Alaska and, you've got me curious, will ask him if he knows if his tanks have ever been replaced. BTW what does KUHL stand for?

Tator

 

[mvweebles]

I too agree with much of what Jungpeter states. I disagreed with the conclusion of 20-years. I had a friend who replaced a fuel tank on a Cal 31 sailboat. Wrong aluminum alloy and he placed it on a rubber pad that trapped water. It corroded through in a bit over a year.

TF gets a lot of newbies asking what they should look out for. Invariably, a chorus of fuel tank cautions. Not because the steel itself is faulty, and on a GB original install is typically fine, but the issue is water intrusion due to teak decks or leaking o-rings on the deck fuel fill. They are tough to diagnose during a survey but as long as the tanks have been kept away from stray water, they can last for decades.

Anymore, taking on bad fuel is becoming a myth, at least in the US. Not saying it can't happen, just saying bad fuel tanks are a major environmental problem with huge fines and regular inspection. Points of water egress along the supply chain have been largely remediated.

Peter

 

[Xlantic]

I am also in agreement with Jungpeter in terms of the drivers of tank failure. But I don't see how he then concludes that tanks have a 20 year life: it can be as little as one year (Peter's example above) or 50 years (and hopefully many more) in my case and others posted here.

One needs to look at the specifics of each case and that is what what the OP needs to do, possibly aided by our collective experience.

 

[GB32Patience]

GB32 Fuel Tank

Just a few quick notes as I have 1978 GB32 and cut out my port tank last spring and replaced with a plastic Moeller.
- Cutting out the tank is a bear and yes, messy, but doable... lots of saw blades, don't forget ear protection..., its LOUD.....main issue is that these tanks have internal baffles that break the tank into 6 internal spaces and they hold the tank together when you think it should come apart.... more cutting....
- Cutting an inspection hatch, only allows access to one of the internal baffled spaces. Taking that approach, you would need 6 inspection hatches.
- When all is said and done, my tank was very much intact, with no apparent rust spots.
- The original reason of replacing and cutting out the tank was that any fuel that went into the tank, came out filthy... 45 years of gunk... the bottom of the tank literally looked like 1" inch of moss, or peat bog..... not sure how that could have been cleaned out with all the baffles..
- When and if you replace your tank, make sure you calculate the weight, location and distribution. Your current steel tank is probably in the range of 150-200 Lbs. I put in a physically smaller plastic tank (approx. 40 Lbs) and between the lighter tank and less fuel, am now working on a bit of a trim issue. Will be solved with additional fuel or water tankage but I should have paid a little more attention to this topic.
Good luck!