Plastic fuel tanks

[Tjome]

I recently purchased a GB36 Classic from 1989 and we are very happy with the boat.

One of the advantages at the time of purchase was that the diesel tanks were replaced in 2017; the new tanks are made of plastic and manufactured by Tek-Tanks in England.

Now I am wondering if there are increased fire risks with having plastic tanks in the same engine room as the diesel engines (two Cummins 5.9)?

I feel some concern about this and would greatly appreciate comments and opinions!

/Tjome

 

[Comodave]

I would not be concerned if the tanks are certified. Certification includes built to specs, properly tested and labeled as such. Diesel is actually pretty difficult to catch on fire. Gas on the other hand is easy. I have put a road flare into diesel and it would not ignite. We were doing a fire extinguisher test for crew members and the local fire chief floated diesel in a pan of water. He tried matches and all the way up to the flare and couldn’t get it to ignite. I told him add an ounce of gas and then it went right up. The first candidate put the fire out. Then the diesel was easier to ignite since it was hot. But ambient diesel it tough to ignite. Spray diesel onto a hot turbo and it will ignite easily.

 

[Mambo42]

I have them as well and they are right next to the engines. The engines will reach about 80 degrees Celsius, while the diesel self ignite temperature is 210 degrees Celsius. So we are not even close to the self ignition temperature of diesel. The tanks are made for holding the diesel and are made for use in the engine room, so it will be perfectly fine.

 

[psneeld]

Replaced my steel tanks with plastic tanks and was never happier. No issues in over 15000 miles of cruising.

After replacing with plastic, fuel gauges and stabbing them for quantity became obsolete.... just look and at least on mine I could see the exact fuel state.

 

[Frosty]

I recently purchased a GB36 Classic from 1989 and we are very happy with the boat.

One of the advantages at the time of purchase was that the diesel tanks were replaced in 2017; the new tanks are made of plastic and manufactured by Tek-Tanks in England.

I feel some concern about this and would greatly appreciate comments and opinions!

/Tjome

Since you would like to be reassured all is good (so would I on my own boat), you might want to go to the Tek Tank website (link below) and look at their installation instructions/specs and compare them to your tanks. If something's not right, you can correct it, and if all is well, you'll feel good about it. I took a look and they have supporting documentation you can download.

Unrelated to diesel fuel or Tek Tanks brand, I have had to make adjustments to a plastic fuel tank installation in the past. The original installer had not followed the mfgr's installation instructions. Specifically that the (plastic) tanks were to be supported in a certain way, and that they required X% of space left for expansion between the tanks and any "corraling" structure.

The one thing I don't love about plastic tanks is that the smell of fuel permeates the walls (or at least can, on some tanks/fuels). Otherwise they have a number of advantages.

Tek Tank's website:

Plastic Tank & Bespoke Product Manufacturer | Tek-Tanks Ltd | The manufacture and supply of plastic tanks and custom plastic fabricated products.

Plastic Tank Manufacturer specialising in Bespoke Plastic Solutions for Leisure & Commercial Marine, Agriculture, Horticulture, Transport & other industries.

www.tek-tanks.com

 

[DDW]

Personally I'd prefer plastic tanks. There are a million or so light diesel trucks sold every year with plastic tanks, for decades now. And probably hundreds of millions of diesel cars.

If your engine room is hot enough to melt the plastic tanks, you've already got big enough problems to think about getting off.

 

[Tjome]

Since you would like to be reassured all is good (so would I on my own boat), you might want to go to the Tek Tank website (link below) and look at their installation instructions/specs and compare them to your tanks. If something's not right, you can correct it, and if all is well, you'll feel good about it. I took a look and they have supporting documentation you can download.

Unrelated to diesel fuel or Tek Tanks brand, I have had to make adjustments to a plastic fuel tank installation in the past. The original installer had not followed the mfgr's installation instructions. Specifically that the (plastic) tanks were to be supported in a certain way, and that they required X% of space left for expansion between the tanks and any "corraling" structure.

The one thing I don't love about plastic tanks is that the smell of fuel permeates the walls (or at least can, on some tanks/fuels). Otherwise they have a number of advantages.

Tek Tank's website:

Plastic Tank & Bespoke Product Manufacturer | Tek-Tanks Ltd | The manufacture and supply of plastic tanks and custom plastic fabricated products.

Plastic Tank Manufacturer specialising in Bespoke Plastic Solutions for Leisure & Commercial Marine, Agriculture, Horticulture, Transport & other industries.

www.tek-tanks.com

Thank you for the great feedback from several "trawlers" !

It’s true that I am quite concerned about the risks associated with plastic tanks.

I have contacted Tek-Tanks, and they advise against placing plastic tanks in the engine room. According to Tek-Tanks' specifications, plastic tanks can withstand 140 degrees Celsius for two minutes before melting. They refer to a standard regarding this. Tek-Tanks recommends building in the plastic tanks so that there is a protective bulkhead between the tanks and the engine room. I have spoken with boat inspectors in Sweden, and they see no problem with having plastic tanks in the engine room.

That said, I am a bit confused about what is actually safe.

/Thomas

 

[Mambo42]

Thank you for the great feedback from several "trawlers" !

It’s true that I am quite concerned about the risks associated with plastic tanks.
According to Tek-Tanks' specifications, plastic tanks can withstand 140 degrees Celsius for two minutes before melting.

That said, I am a bit confused about what is actually safe.

/Thomas

And when exactly is it going to get 140 degrees Celsius in your engine room ? My engine room does not get above 35 degrees Celsius anymore, after I installed some heavy duty ventilators. Before I had those it was 65 degrees Celsius in my engine room, that was basically with no ventilation, still not anywhere near 140 degrees.

If I gets to 140 degrees Celsius in your engine room you have a much bigger problem, you have a fire onboard and if your boat is made of GRP that is also the time you need to abandon ship. Once GRP burns there is no holding back, your boat is finished. The fuel tanks would be the last thing I would worry about at that time.

 

[High Wire]

Just for perspective, 100C is the boiling point of water 212 F. So 140 C is well above that. The only practical way to get there is dry diesel exhaust or fire. If you’re still worried you might put a fire retardant barrier between the tanks and engines.

 

[Bud]

I would not put plastic fuel tanks in an engine room without protective bulkheads. I would be afraid of some kind of exhaust leak event or a puncture. The expansion and contraction would also be a concern for me.

Bud

 

[Comodave]

I can’t imagine an engine room getting over 140C or 284F. If it does then you have waaay too little ventilation going on. We had a center console with plastic fuel tank and it did permeate a bit of gas smell but not much and was never a problem in the 7 years we had it. Not sure diesel would do that because it seems that gas is more of a solvent than diesel. I could be wrong though.

 

[Bud]

We have a 26ft Glacier Bay Cat with two plastic tanks built in under the deck, one in each hull. They are in their own designed space seperate from everything else with seperate access, protected from the engines which are outboards. It to will permeate a bit of a gas smell.

Bud

 

[psneeld]

Mitigate any risks of abrasion, exhaust leaks, loose objects violently hitting them, adequately ventilate/cool the engine room, etc...etc..

I can't vouch for your tanks, but most installed plastic tanks here in the US I wouldn't give a second thought to their safety and if not particularly large ones actually prefer them.

Can't state any specific safety issues or statistic I have read about plastic diesel tanks. Been around for a long while in many different kinds of boats with no notable higher rate of problems, especially when compared to poorly installed aluminum tanks that have a scary failure rate.

A quick Google search revealed this as a general opinion of them....

"

How safe are plastic diesel tanks in boats?​

Plastic diesel tanks in boats are generally considered safe when they are properly constructed and certified. Here are some key points to consider:

• Certification: Plastic tanks must be certified to meet safety standards, ensuring they are built to specifications and properly tested.
• Fire Resistance: Plastic tanks are designed to withstand fire, with a fire resistance of at least 21/2 minutes, which is crucial for safety.
• Corrosion Resistance: HDPE tanks are resistant to corrosion, which is a significant advantage over aluminum tanks.
  https://www.bing.com/ck/a?!&&p=d803...WludW0tdGhlLXByb3MtYW5kLWNvbnMtZGViYXRl&ntb=1
  
  
• Durability: Plastic tanks are known for their durability and can outlast aluminum tanks in many cases. https://www.bing.com/ck/a?!&&p=d803...WludW0tdGhlLXByb3MtYW5kLWNvbnMtZGViYXRl&ntb=1
• Customization: While plastic tanks are less customizable than aluminum tanks, they are still available in various sizes and shapes to fit different boat designs.
  https://www.bing.com/ck/a?!&&p=d803...WludW0tdGhlLXByb3MtYW5kLWNvbnMtZGViYXRl&ntb=1
  It's important to ensure that the plastic tank is installed correctly and maintained properly to avoid any potential issues. Regular inspections and maintenance are recommended to ensure the tank remains safe and reliable.
  
  3 sources.

 

[Bud]

Mitigate any risks of abrasion, exhaust leaks, loose objects violently hitting them, adequately ventilate/cool the engine room, etc...etc..

I can't vouch for your tanks, but most installed plastic tanks here in the US I wouldn't give a second thought to their safety and if not particularly large ones actually prefer them.

Can't state any specific safety issues or statistic I have read about plastic diesel tanks. Been around for a long while in many different kinds of boats with no notable higher rate of problems, especially when compared to poorly installed aluminum tanks that have a scary failure rate.

A quick Google search revealed this as a general opinion of them....

"

How safe are plastic diesel tanks in boats?​

Plastic diesel tanks in boats are generally considered safe when they are properly constructed and certified. Here are some key points to consider:

• Certification: Plastic tanks must be certified to meet safety standards, ensuring they are built to specifications and properly tested.
• Fire Resistance: Plastic tanks are designed to withstand fire, with a fire resistance of at least 21/2 minutes, which is crucial for safety.
• Corrosion Resistance: HDPE tanks are resistant to corrosion, which is a significant advantage over aluminum tanks.
  https://www.bing.com/ck/a?!&&p=d803...WludW0tdGhlLXByb3MtYW5kLWNvbnMtZGViYXRl&ntb=1
  
  
• Durability: Plastic tanks are known for their durability and can outlast aluminum tanks in many cases. https://www.bing.com/ck/a?!&&p=d803...WludW0tdGhlLXByb3MtYW5kLWNvbnMtZGViYXRl&ntb=1
• Customization: While plastic tanks are less customizable than aluminum tanks, they are still available in various sizes and shapes to fit different boat designs.
  https://www.bing.com/ck/a?!&&p=d803...WludW0tdGhlLXByb3MtYW5kLWNvbnMtZGViYXRl&ntb=1
  It's important to ensure that the plastic tank is installed correctly and maintained properly to avoid any potential issues. Regular inspections and maintenance are recommended to ensure the tank remains safe and reliable.
  
  3 sources.

Plastic tanks are fine as long as they are protected from the engines, engine exhaust, and machinery appropriately. It is basic "common sense". The extreme up and down temps of an engine room would promote more expansion and contraction and reduce the life of the tank. I do not know of any manufacturers that put plastic tanks for diesel fuel in the engine room.
Bud

 

[psneeld]

I wasn't very worried with all the plastic fuel tanks underneath and plastics used uder the hood of cars and trucks where nearby exhaust and road tempz in places are as or hotter than most engine rooms I have been in.

I at most would put a foil covered, fireproof sound insulation on something between the tanks snd engines if very close.

 

[DDW]

All things on a boat are a compromise - including tank material - and all risks are relative. An aluminum or steel tank has the risk of corroding through a leaking its contents into the engine room. That is not a theoretical risk as even a cursory search of this site will prove. And it is usually an unseen hazard until failure. A plastic tank has the risk of melting or perhaps wearing through. This risk is largely testable and observable. Look for rubbing points, hold your hand on the tank nearest the exhaust.

Both metal and plastic have risks. Metal is not risk free. I'd rather have the plastic, as installed in literally billions of cars and trucks.

 

[Tjome]

Thank you so much for all your comments and tips!

Several of your remarks have encouraged me to take some action to protect the plastic tanks from exposure to high heat.

I realize that I need to review the air intake and exhaust in the engine compartment and make sure that air is properly ventilated, both for the space with the plastic tanks and for the engines.

Thank you all for your feedback!

/Thomas

 

[Capt Pappy]

We went thru a big ordeal with Sportsman in 2023 regarding the plastic fuel tank in our 23' center console. The fuel gauge stopped working (the always seem to do) and when I opened the filler cap, there was immense pressure let loose. Thus, we brought the boat in and the dealership said because we filled the fuel tank with jerry cans the tank became overfilled and over-pressurized causing the plastic tank to expand.

After convincing us the expanded fuel tank was of no danger and putting in a new sending unit, not had any issues or pressure build-up, but admittedly have not filled her with the cans but rather at the marina with the typical hose.

At some point in time, they changed the fuel filler system to some pressurized system from the old over spill method to appease the EPA I assume.

But I imagine, the older trawlers have the 'over-spill' valve system and not this pressurized function, so I doubt any of this applies here?

and if you can view the plastic tank, then of course that is your best fuel gauge -- in all the boats I owned, none of the fuel gauges worked so well --- even ran out of gas in a 27' Baja right in the middle of the Houston ship channel about 40 years ago. A barge was headed staright for us. I jumped into the water with a line to the bow to try and swim us to safety, when thankfully a gentleman driving by in a skiff thru us a line and towed us out of harms way.

 

[jgwinks]

With liquid fuels it's not the liquid that burns but the vapor it creates in evaporation. Gasoline evaporates at a very low temperature so there's nearly always enough flammable vapor present to burn or even explode. Diesel evaporates at a very high temperature so there's almost never enough vapor present to burn. If your engine room gets that hot you will probably be treading water already.