Fiberglass Diesel Fuel Tank

[downunder]

Originally Posted by steamgoat

Seems to me a 62gall tank is awfull heavy for a 34 ft boat. My 38ft has a 50 gall tank and I am replacing it this winter,the new tank will be smaller. It would take me a long time to use 50gal, I would rather carry the extra in a couple of jerry jugs which may be required in far away places.
Just a thought, Bruce.

Seems more sensible to have the larger tank and not have to carry extra jerry cans lashed to the deck.

Remember the larger tank will have weight right where it is needed. does not have to be filled to the brim if cwerapacity is not needed. most crusing vessels have inadequate tankage and thereby are always chasing fuel.

[Sailmonkey]

We're also gearing up to build a figerglass fuel tank. The custom shape to increase capacity makes this a desirable route for me (that and it's not aluminium). I'm not breaking new ground, simply following in the footsteps of a fellow Allied Seawind II owner who's posted his tank build here

Voyager's New Diesel Tank

[Cheechako]

Remember the larger tank will have weight right where it is needed. does not have to be filled to the brim if cwerapacity is not needed. most crusing vessels have inadequate tankage and thereby are always chasing fuel.

Actually in the link given, the weight is NOT where you want it.... in the stern behind the engine..

Anyone know what he used for sealant on the fittings etc?

[Annie in WA]

O.K, here's the end of the story. After starting in on designing the fiberglass fuel tank we decided to walk 100 feet down the street and hired an experienced aluminum tank maker after thoroughly discussing his manufacturing technique. Here's why:

1. Time. It was taking time to figure out how the tank would be constructed, what fittings to buy and how they would attach to the tank, baffle design, mounting system in the boat so that the fiberglass tank would be strongly supported, etc.

2. Engine. The tank must be designed, built, and installed before the engine goes in. The engine is close to ready, the boat is hauled out, and it is almost Oct.

3. Difficult Project Management. My husband and I started working with a talented young fiberglasser who had never built a fuel tank. I'm a planner and my job is research and buying materials, my husband is handy and has a lot of skills although fiberglassing is not one of them. While this combination of three would seem to be ideal, the communication didn't work well when three people who had never built a fiberglass tank tried to actually do it together. See #1.

4. Money. When all is said and done, the aluminum tank will be less expensive by a couple of hundred dollars.

I'm honestly not sure what I've learned from this experience; I haven't quite sorted it out yet. I do know that the process of putting a new tank in the boat is a lot more complicated than I had thought. Perhaps, "look before you leap"?

[gjordan]

Annie, please keep us posted on how the new tank works out and how you do your mounting to avoid electrolisis? Also, if you dont mind telling us what the new tank cost? This has been a good thread.____Grant.

[DeepFrz]

If the tank is mounted so that water does not lie against the outside and you keep the insides clean, an aluminum tank will last a very long time. It is especially important to make sure that water is removed from the tank often, especially with the new diesel fuels containing alcohol. By the way, some of the new diesel attacks some epoxies as well.

[Roy M]

Sorry, but we're going to need some facts behind the statement that NEW diesels can affect SOME epoxies. Don't claim it unless you can prove it.

[DeepFrz]

I'm talking about bio-diesel. The last link lists a number of common coatings including Epoxy and states that epoxy has "low resistance to phenols and methanol". There are some new epoxy formulations that are, according to the manufacturers, suitable for bio-diesel tanks. The paper at the Americoat link below states:

• Most existing tank coatings based on standard epoxy
technology are also resistant to FAME
• Most existing tank coatings based on standard
epoxy technology are also
resistant to E5
• BUT : ethanol/fuel mixtures of >5% are problematic!
• Many failures of coating systems are to be expected in
the coming years
• The impact on this on the protective coatings market should
not be underestimated.
• Tank owners require the next generation solvent free phenolic
epoxy tank linings that are resistant to latest
gasoline blends from E5 to E100 and biodiesel.

http://info.ogp.org.uk/standards/11L...entation04.pdf
http://www.deq.state.or.us/lq/pubs/f...USTSystems.pdf
BoatUS: Seaworthy
GRP fuel tanks [Archive] - Yachting and Boating World Forums
http://www.nansulate.com/pdf/Biofuel...nal_052011.pdf

[David M]

Originally Posted by Annie in WA

O.K, here's the end of the story. After starting in on designing the fiberglass fuel tank we decided to walk 100 feet down the street and hired an experienced aluminum tank maker after thoroughly discussing his manufacturing technique. Here's why:

1. Time. It was taking time to figure out how the tank would be constructed, what fittings to buy and how they would attach to the tank, baffle design, mounting system in the boat so that the fiberglass tank would be strongly supported, etc.

2. Engine. The tank must be designed, built, and installed before the engine goes in. The engine is close to ready, the boat is hauled out, and it is almost Oct.

3. Difficult Project Management. My husband and I started working with a talented young fiberglasser who had never built a fuel tank. I'm a planner and my job is research and buying materials, my husband is handy and has a lot of skills although fiberglassing is not one of them. While this combination of three would seem to be ideal, the communication didn't work well when three people who had never built a fiberglass tank tried to actually do it together. See #1.

4. Money. When all is said and done, the aluminum tank will be less expensive by a couple of hundred dollars.

I'm honestly not sure what I've learned from this experience; I haven't quite sorted it out yet. I do know that the process of putting a new tank in the boat is a lot more complicated than I had thought. Perhaps, "look before you leap"?

The aluminum boat I operate has two 135 gallon tanks without baffles and neither has any corrosion whatsoever. If you learn what to do with aluminum and what never to do then corrosion is not a problem. Keep in mind that baffles will reduce your ability to thoroughly clean out the tank if that day ever occurs. People with aluminum corrosion problems are doing something wrong. It is even possible to thread stainless steel valves directly onto aluminum pipe nipples. I do this on the boat and it is not a problem. Corrosion problems with aluminum are overblown because of all the people who have done something wrong.

[Annie in WA]

In answer to Grant's question on how the aluminum tank has turned out:

The tank is built, tested out well, and is waiting to be installed. We put two inspection ports in the side to be able to clean out each chamber (one central baffle) if needed. Putting ports in the side is controversial and the aluminum mechanic recommended against it but there wasn't room to access them if they were put in the top and Steve D'Antonio, a boat inspector/yard manager that I respect highly, said ports in the side were o.k. The actual tank cost $1,200 without mounting. My estimate for fiberglass was $1,000. The tank will be mounted on marine plywood stringers encased in fiberglass with fiberglass strips adhered to the bottom of the tank with 5200. There will be tabs on the corners and a bulkhead on one side to hold it in place so there is air around it, yet it is secure and can't shift.

Mounting design has proven challenging in large part because floor and bulkheads are not square. This would have been the same with a fiberglass tank. The tank is a little smaller than the original (60 versus 62 gallons) since it was such a tight fit getting the original out through the companionway. Can't wait till we're done.

[minaret]

Originally Posted by Annie in WA

In answer to Grant's question on how the aluminum tank has turned out:

The tank is built, tested out well, and is waiting to be installed. We put two inspection ports in the side to be able to clean out each chamber (one central baffle) if needed. Putting ports in the side is controversial and the aluminum mechanic recommended against it but there wasn't room to access them if they were put in the top and Steve D'Antonio, a boat inspector/yard manager that I respect highly, said ports in the side were o.k. The actual tank cost $1,200 without mounting. My estimate for fiberglass was $1,000. The tank will be mounted on marine plywood stringers encased in fiberglass with fiberglass strips adhered to the bottom of the tank with 5200. There will be tabs on the corners and a bulkhead on one side to hold it in place so there is air around it, yet it is secure and can't shift.

Mounting design has proven challenging in large part because floor and bulkheads are not square. This would have been the same with a fiberglass tank. The tank is a little smaller than the original (60 versus 62 gallons) since it was such a tight fit getting the original out through the companionway. Can't wait till we're done.

You may be seeing some of the advantages of a glass tank here, especially an integral tank. Instead of installing on stringers and going to great lengths to make sure that the tank touches nothing and is well secured, in the process wasting much of the available space, you can use every square inch of available space and never have to worry about tank movement or degradation.

[Agape39]

Originally Posted by Annie in WA

In answer to Grant's question on how the aluminum tank has turned out:

The tank is built, tested out well, and is waiting to be installed. We put two inspection ports in the side to be able to clean out each chamber (one central baffle) if needed. Putting ports in the side is controversial and the aluminum mechanic recommended against it but there wasn't room to access them if they were put in the top and Steve D'Antonio, a boat inspector/yard manager that I respect highly, said ports in the side were o.k. The actual tank cost $1,200 without mounting. My estimate for fiberglass was $1,000. The tank will be mounted on marine plywood stringers encased in fiberglass with fiberglass strips adhered to the bottom of the tank with 5200. There will be tabs on the corners and a bulkhead on one side to hold it in place so there is air around it, yet it is secure and can't shift.

Mounting design has proven challenging in large part because floor and bulkheads are not square. This would have been the same with a fiberglass tank. The tank is a little smaller than the original (60 versus 62 gallons) since it was such a tight fit getting the original out through the companionway. Can't wait till we're done.

WOW $1200 for a 60 gal. tank! I just had one custom built out of 316 stainless for $600, material costs were $426..... You need better contacts, how thick was the material?

[minaret]

Originally Posted by Agape39

WOW $1200 for a 60 gal. tank! I just had one custom built out of 316 stainless for $600, material costs were $426..... You need better contacts, how thick was the material?

I believe aluminum costs more than stainless, particularly the labor to weld.

[DeepFrz]

It could also depend on whether the tank was built by a tank fabricator following all the requirements for a fuel tank or if it was just built by a local welder who knew nothing about building fuel tanks.

[CarlF]

The biggest risk with well made aluminum tanks is corrosion at the mounting points.

My tanks sit on small hard rubber pads that won't hold any moisture. Does your tank builder have experience with the 5200 to fiberglass strip method? It sounds like a clever idea but I've had my share of clever ideas not work.

If I ever had to replace my tank (not likely), I'd weld on aluminum stand-offs or tabs so that any corrosion at the mounts wouldn't be in the skin of the tank.

Carl