Tank Material

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wizard

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Joined
Nov 2, 2011
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Hello,
We are considering purchasing a trawler. We have attended a couple of Trawlerfests, etc, and are continuing to educate ourselves on the aspects of cruising. We plan to purchase a used boat in the $350K to $400K range, and have all but settled on Krogens, Selenes, Grand Banks and Nordhavns in the 39 to 46 foot range.
I have read a good bit about fuel tank material, and although black iron and steel have been used sucessfully for decades, I would prefer to void both, in favor of aluminium, FRP, etc.
I cannot seem to find a point when (and if) these brands made a switch to other than steel. And fuel tank material on particular boats on Yachtworld is rarely mentioned, even though I would think that would be helpful information to most buyers.
It would be helpful to know that (for example) Grand Banks switched to X fuel tank material in X year, so that we could focus our search from that point forward.
Any advice would be really appreciated.

Thanks,
Wizard
 
Black iron tanks last for decades. Keep them dry inside and out - that's all. Even if the tanks on the boat you find will need replacing, it's a nuisance but an easy fix. To me, that alone seems like a strange show-stopper, especially with your budget? Find the boat you want and deal with the tanks at survey.
 
Black iron is not really iron, it is simply a grade of steel. All the commonly used metals, stainless, aluminum and steel ("black" or not) make for acceptable tanks. All will corrode if not installed properly so for me, installation would be a bigger factor than material.
 
Wizard

Just go to the company's web site on the brand and contact them with your questions. They will tell you anything you need to know.

Good luck

Happy cruising

H. Foster
 
Hi Wizard,

Steve D'Antonio has posted a pretty good treatise on tank material titled "Tanks-Fuel, Water, and Holding". Unfortunately, I'm unable to locate a link to the article (hopefully somebody else can do so), which originally appeared in Passagemaker Magazine in September 2001. His website has a link to the article, but it leads me into a never-never land of Soundings Magazine.

And, despite a forum comment that bad fuel tanks are "...a nuisance but an easy fix...", it just ain't so. In my opinion, bad fuel tanks, whether discovered at survey or before, are a non-starter. Run, don't walk, off the boat.

Regards,

Pete
 
Pete your "opinion" is noted.
 
Wizard,
I have a 1990 model Grand Banks 46 Classic. It had steel/black iron tanks, and so did a 1991 same model that I looked at before we bought. I have since replaced the port side steel tank with three stacked aluminum tanks. So far, the starboard side tank is holding it's own.
Not sure when Grand Banks changed materials for their fuel tanks.
Hope that helps a little.
Chuck
 
Most production "trawlers" require engines to be removed before the fuel tanks can be fully accessed. A deal breaker for me too.

Need convincing ? Watch this Youtube of the bottom of a Grand Banks 42 being cut out to get tanks out. A pretty common method.
 
Slow Flight was fitted with stainless for fuel (4X150's) and water (2x150's and 1x100) All tanks are baffled, and have two 8" inspection plates each. It looks like a first class installation. I hope it is, because we plan to have the boat for a good many years.
 
With what I have heard, researched, and personally experienced with tanks, fuel or otherwise, especially in view of possible (? read probable), developments with bio-diesels etc in the future, I would go for the appropriate grade plastic/composite fuel tanks any day over any metal. For fuel, water, or holding tanks. But maybe that's just me..?
 
The >best< material for a fuel tank is monel , unfortunatly it is pricy and the first purchasers are not knowledgible enough to demand it , and the boat assembler will not supply a premium item unless forced to.

Most common materials can be made to work , bases mostly on the quality of the initial installation , and maint after.

For a refit multiple plastic tanks ,(so they can be drained and left empty), when extreme range is not required and a Quality gravity day tank would work for most folks.
 
Here is a little tip, no mater what the tank is made of, they will all condensate, so find the drain plug at the lowest point, put a piece of duct tape over the tank vent on the side of the boat, then stick the hose from a shop-vac in the fuel fill hole. Turn the vacuum on and you can remove the drain plug in the tank without spilling a drop. Install a fitting and length of clear hose in the tank drain hole, then turn the vac off. Watch while the bad stuff drains in a 5 gal bucket or two. Once you see clean fuel, turn the vacuum back on and put the plug back in the tank. You now have a clean tank. Note! This is for diesel only. Not gas!!!!!!!
 
Pretty sure the current train of thought is condensation is darn near a non problem.

My boss salvages boats and for years I always wondered how much condensation would actually form...out of dozens of tanks (empty to near full) laying around the yard....few had more than a teaspoon or two of water in them and some had been there for years.

Sure, some tanks are worse than others, some installs are worse than others and some climates are worse than others..so it can and does happen...but all in all the amount of condensate in the average tank is usually easily taken care of by a water separating filter.

I don't always agree with this guy but on this we do....

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

"Frequently we hear it said that the cause of water in fuel tanks is due to condensation. I have long doubted this assertion but the issue has come up so frequently that I was finally motivated to try prove to the point. The basis of my belief or assumption is that................."
 
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psneeld said:
Pretty sure the current train of thought is condensation is darn near a non problem.

My boss salvages boats and for years I always wondered how much condensation would actually form...out of dozens of tanks (empty to near full) laying around the yard....few had more than a teaspoon or two of water in them and some had been there for years.

Sure, some tanks are worse than others, some installs are worse than others and some climates are worse than others..so it can and does happen...but all in all the amount of condensate in the average tank is usually easily taken care of by a water separating filter.

I don't always agree with this guy but on this we do....

The Myth of Condensation in Fuel Tanks by David Pascoe: Boat Maintenance, Repairs and Troubleshooting

"Frequently we hear it said that the cause of water in fuel tanks is due to condensation. I have long doubted this assertion but the issue has come up so frequently that I was finally motivated to try prove to the point. The basis of my belief or assumption is that................."
Click to expand...

I agree psn. I commit the crime all the time of never having my tanks full, and here in Queensland with high temps and humidity, and yet quite cool night temps, in winter especially, if condensation was an issue, surely I'd get it. Yet I never get more than a tspfull of water out of the separator under the primary filter...and...my tanks drain from the bottom, not through a pick-up tube, so if there was water there, it would come through.
 
A drawback with 34-year-old aluminium tanks is crevice corrosion in the welds. I have had two slight leaks caused by this - water drops sit in any little hollows in welds on the bottom edges. Fortunately, I've been able to access both sites from the outside and peen over the weld with a ball-peen hammer, as advised by a very experienced engineer. Don't know what I'll do if it happens in a less accessible location where I can't get a swing at it - maybe epoxy putty? Composite or plastic tanks seem to be problem free...
 
We had to replace our fuel tanks shortly after buying our Willard 30 w "black iron" tanks. I did a lot of asking around and only one material was recommended much more than any other. Aluminum. We had aluminum tanks made and did the dirty R&R job along w installing a new engine. Had to take the old Perkins out anyway to get at the tanks.

If I had it to do over again I'd give plastic much more consideration.
 
30 year old rusted or corroded tanks on a trawler are a REALLY BAD DEAL. Unless the boat is really cheap and you really like it, run ,run, and run faster. Been there done that. Every metal tank I install is triple coated with coal tar epoxy and set on 1/2 inch rubber strips. I fully expect them to last 30 years. YMMV
 
A couple days of solo cutting (1 day with friend) with a recip saw and sliding in a couple new poly tanks on platforms that can be quickly built and painted out of common materials....how hard is that? You can customize and redo the engine room including paint and storage while the tanks are out.

While not the most fun job in the world...certainly within the abilities of almost any handyman...and for me I doubled my engine room storage space, made the side decks completely clear to be able to sit or lie down 360 degree access to my engine, the new poly tanks cost around $700 with fittings and are great because you can see the level and can easily be removed for cleaning any time you want.
 
It would have taken a week and an incredible number of blades to cut the 400 gallon side tanks out of my trawler. The 250 gallon tank under the floor midship required the complete dissassebly of the boat in that area. Both enterior walls and the sole had to be removed just to get to the top of the tank. We then cleaned it completely and cut it apart with a oxy/acetilyne torch. All of these tanks were 1/4 inch "black iron, aka just plain mild steel. The lower tank had a small leak that was repairable and the side tanks did not leak. No way could I not change them out and sleep well at night. I will not refit a boat just to redo my shortcuts later. I like poly tanks just fine but they dont come in the sizes I needed and are not baffled. I did not want to reduce my tankage, preferring to increase it, substantially if possible. All were replaced with custom built 5086 1/4 in aluminum to commercial specs and installed correctly. I cant imagine how much this would have cost in a boatyard, well over $50,000 if done my way I'm sure. But it is done correctly and will not need redoing in my, and probably the next owners lifetime. Tankage on most boats constitutes a major expense if they need work, no way around it. Poly tanks are a good stop gap measure. Patches and epoxy lining work to. Just not for me. While the engines were out of my 48 sportfisher I removed the fuel tanks "just to look" and found a small area on the 350 gallon mid tank about the size of a dime that was corroded about 1/8 inch deep. It was cut out and repaired. They had not previously leaked but had I not removed and looked at them they would have been leaking eventually. I also installed 12x12 clean out/inspection plates in every baffled section, all in all a total of 16 in two tanks. Now cleaning them is easy. I coated the tanks with coal tar epoxy and installed them on 1/2 thick rubber strips. I documented the process, with pics, just in case the next owner wants proof of the work done, in both cases. Non of this was easy or cheap. I knew when I bought the boats exactly what I was going to do so I was not surprised, it was just part of the deal. I strongly suggest anyone buying an older boat look at tank replacement as "probable" and proceed with that in mind.
 
kulas44 said:
It would have taken a week and an incredible number of blades to cut the 400 gallon side tanks out of my trawler. The 250 gallon tank under the floor midship required the complete dissassebly of the boat in that area. Both enterior walls and the sole had to be removed just to get to the top of the tank. We then cleaned it completely and cut it apart with a oxy/acetilyne torch. All of these tanks were 1/4 inch "black iron, aka just plain mild steel. The lower tank had a small leak that was repairable and the side tanks did not leak. No way could I not change them out and sleep well at night. I will not refit a boat just to redo my shortcuts later. I like poly tanks just fine but they dont come in the sizes I needed and are not baffled. I did not want to reduce my tankage, preferring to increase it, substantially if possible. All were replaced with custom built 5086 1/4 in aluminum to commercial specs and installed correctly. I cant imagine how much this would have cost in a boatyard, well over $50,000 if done my way I'm sure. But it is done correctly and will not need redoing in my, and probably the next owners lifetime. Tankage on most boats constitutes a major expense if they need work, no way around it. Poly tanks are a good stop gap measure. Patches and epoxy lining work to. Just not for me. While the engines were out of my 48 sportfisher I removed the fuel tanks "just to look" and found a small area on the 350 gallon mid tank about the size of a dime that was corroded about 1/8 inch deep. It was cut out and repaired. They had not previously leaked but had I not removed and looked at them they would have been leaking eventually. I also installed 12x12 clean out/inspection plates in every baffled section, all in all a total of 16 in two tanks. Now cleaning them is easy. I coated the tanks with coal tar epoxy and installed them on 1/2 thick rubber strips. I documented the process, with pics, just in case the next owner wants proof of the work done, in both cases. Non of this was easy or cheap. I knew when I bought the boats exactly what I was going to do so I was not surprised, it was just part of the deal. I strongly suggest anyone buying an older boat look at tank replacement as "probable" and proceed with that in mind.
Click to expand...

We need a "Like" button !
 
Boatpoker, try the "Thanks" button , not public, but gets to the right place.
 
Every boat and situation usually is a little different...that's why I made my posts ...to show SOME of the people it may be no big deal for some boats or their situation...but tank removal or replacement IS NOT NECESSARILY THIS -

post #18 - "30 year old rusted or corroded tanks on a trawler are a REALLY BAD DEAL. Unless the boat is really cheap and you really like it, run ,run, and run faster"
 
psneeld said:
Every boat and situation usually is a little different...that's why I made my posts ...to show SOME of the people it may be no big deal for some boats or their situation...but tank removal or replacement IS NOT NECESSARILY THIS -

post #18 - "30 year old rusted or corroded tanks on a trawler are a REALLY BAD DEAL. Unless the boat is really cheap and you really like it, run ,run, and run faster"
Click to expand...

I agree. A big project perhaps, but no bigger than many other possibilities on a used boat esp if you are a do-it-yourselfer.
 
That is correct, just assess the situation and if tank removal is problematic, look elswhere. Even if there are no leaks now, most older metal tanks eventually will leak. If you can "fix" the problem yourself to your satisfaction, or have a yard do it for a price that you are ok with then dont consider it a deal breaker.
 
It's funny...this discussion is exactly why I have little love for many production boats.

Skipperdudes philosophy is aligned with mine..."If you can't repair it maybe it shouldn't be on a boat"....

I'm not that much of a purist...but when I eyeball a boat...I look for inaccessible systems or difficulties in removing large objects like gensets, engines, tanks, etc....

Every repair I make, I usually leave it easier to repair or troubleshoot the next time.

So kulas44 please don't feel like I'm slamming your concept as I might walk from a boat with inaccessible tanks, even if they were in good shape. I'm just saying that every boat and owner has a different set of priorities....and my situation made removing my tanks a priority yet just another one on a long list of projects.

Heck, some of my boating friends don't even need fuel tanks in their boat...they would just get e to tow them to/from their slips if it were allowed...:eek:
 
The PO replaced the black iron tanks on my 1985 KK42 with aluminum tanks. He did the re and re work himself but had an outfit in Bellingham build the tanks. The PO maintains boats for a living and the work looked very well done, but I guess time will tell, as with all things. He also put in a fuel polishing system. This is what it looks like now.
image-280551342.jpg

I should say that cutting out a tanks is a tricky process. I had an above ground oil tank removed. The fellow who did the work used a heavy duty grinder to cut it apart. He had a major fire going on inside the tank. Glad I wasn't doing it! Not what you want to have on a boat!


image-10280472.jpg



Jim, Sent from my iPad using Trawler
 
Last edited:
boatpoker,

A lot of guys post;

"+1 :thumb:"
 
JDCAVE said:
The PO replaced the black iron tanks on my 1985 KK42 with aluminum tanks. He did the re and re work himself but had an outfit in Bellingham build the tanks. The PO maintains boats for a living and the work looked very well done, but I guess time will tell, as with all things. He also put in a fuel polishing system. This is what it looks like now.


I should say that cutting out a tanks is a tricky process. I had an above ground oil tank removed. The fellow who did the work used a heavy duty grinder to cut it apart. He had a major fire going on inside the tank. Glad I wasn't doing it! Not what you want to have on a boat!






Jim, Sent from my iPad using Trawler
Click to expand...

That's why I used a recip saw...no sparks, no appreciable heat...may have taken longer than a grinder, but with minimal ventilation, the saw was perfectly safe as the was no atomized fuel and it was at or below room temp.
 
What's the downside to plastic? Other that the obvious soldering iron or welder's torch.

So far all I've heard is no baffles.
 
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