Reply With QuoteI would cut them out and put side tanks in for sure. But, that is just my opinion.
I just bought a 1974 Frahs 17' flatbottom that I am stripping down and rebuilding. It has twin fiberglass side gas tanks that don't leak, but..... What is the general opinion, should I use them or cut them out and replace them with aluminum tanks?
Thanks
I would cut them out and put side tanks in for sure. But, that is just my opinion.
Funny you should ask. I was just reviewing a piece I wrote a few months back on that very subject. Here's the issue: Ethanol. As everyone knows by now, gasoline has a alcohol in it and more is coming. There have been some serious problems with fiberglass tanks in boats due to the alcohol attacking the laminate and resulting in the tanks leaking. All of the tanks that have had a problem were installed 20 or more years ago. Your tanks are over 30 years old. If they have had gas standing in them for long periods of time then they are probably not long for this world. Since you are rebuilding, I would replace them now while the boat is being taken apart. If you don't do it now, then it will cost you a lot more to do it later. However, if you don't want to, you could give them a pressure test to see if they have a problem. If they can hold 3 psi without leaking then they may be allright. The problem is that the damage done is in the actual fiberglass laminate and you simply can't tell until they start leaking. Here's a link to a report on Ethanol and fiberglass tanks on the Boat US web site. http://my.boatus.com/forum/forum_pos...TID=56486&PN=1
I have a 1974 Spectra with fiberglass tanks that are still in good shape. For how long is unknown. They will be changed out next winter regardless of their condition. The pressure check is a very good idea.
i have some imco stainless tanks i need to get rid of they have a few small dents they are polished stainless $300
I'm running Av-Gas and leave my tanks empty over the winter. My fiber glassed tanks aren't leaking, are only 7 years old or so, and holding fuel fine. Since I'm running Av-Gas, I believe that I am free from having to worry about the gas eating into the fiberglass. Anyone with some knowledge guide accordingly. I don't want to go sawing tanks out of my boat if I don't have to. I like the pressure test, I'll have to try that.
Just don't get crazy with the pressure test. One time I was checking a motocycle tank and my brain got in the way, I forgot to turn the pressure down from around 110psi and when I hooked it up it wasn't pretty.
Yeah watch it with the pressure test. 3PSI MAX No more. Take it to a marine repair place, they should ahve the equipment to do it. Actually you should get your tank and fuel system pressure tested annually anyway.
As for the AV gas, if you leave the tanks empty you should be ok. The to most critical components here are fuel and time, and time is the most important. When fuel is allowed to sit in the tanks for long periods of time, (I'm talking months here) then it goes to work on the glass. If you run the fuel through the engine and leave the tanks empty you should not have a problem. Most of the boats that have the problem are boats that are laid up fot the winter with full tanks. This gives the alcohol time to separate (phase separation if you remember your high school chemistry) and all kinds of chemical reactions have time to take place. Here's a couple of excerpts of stuff I have written on Alcohol and Gas:
Frankly, I feel like the voice crying in the wilderness. I have been telling boat owners and builders for 20 years not to build fiberglass tanks for gasoline. Very few listened. Now there is all this hue and cry. ABYC has also for years recommended that if you build tanks in fiberglass to use resins that are fuel resistant. In fact, gasoline is a solvent and dissolves some resins used in fiberglass without any ethanol present.
Until now there has been no specific research on the effect of alcohol in whatever concentration on tanks except for the research project I did on cross linked polyethylene tanks. That was done because we had seen a lot of problems with fuel hoses and had changed the fuel hose formulation to be resistant. So we were concerned about plastic tanks. But, there were many documented cases over the years of problems due to phase separation with aluminum tanks, (I think we published a consumer alert in 1975 and several thereafter) but the problems with fiberglass were mostly anecdotal because fiberglass was used mostly (probably 99%) for diesel. On the alcohol in aluminum issue, there have been several published recalls. However, we had in our files documented cases of failure of fiberglass gas tanks, maybe 2 or 3. Not a lot, mind you, but enough to make me cautious. Then in recent years people began reporting these. They were all in older boats so the CG had no jurisdiction because the limit is 10 years. So BoatUS took the initiative and put out the word. I thank them for this.
But there was no "the Coast Guard knew this was going to happen" going on here. No smoking gun.
It was strictly a matter of my own judgement and that of others that it wasn't a good idea, but many other well known and reliable people with experience in tank manufacture did not agree.
And actually if you check back you will find that fuel distributors not the petroleum suppliers, have been putting alcohol in gas since the 1970's, usually in amounts of about 5%. So alcohol has been in our gas for a long, long time. (remember Gasohol?) The effects are long term. It takes many years for the alcohol to have an effect. But fiberglass, as we have learned from the blistering problems, is not impervious. It is a semi-permeable membrane and liquids will migrate through it, especially if there are voids and resin starved areas. Well if water can migrate through FRP and cause blistering then alcohol most certainly can.
Let me try to clear up some of this. In my position in the Coast Guard Office of Boating Safety for 20 some years, I was the fuel systems go to guy. As such I sat on ABYC's Fuel and Venitilation Committee, SAE committees, and worked closely with fuel tank, hose and fittings manufacturers and the EPA. Obviously alcohol in the fuel was one of the problems we dealt with.
Alcohol has been in gasoline as an additive for a long time, more than 30 years. Initially it was added as an Oxygenate, that is a chemical that adds oxygen to the fuel and therefore makes it burn cleaner reducing smog. However, it was realized within a short time that this caused problems with boats. First of all it was the fuel hose. Alcohol leeched the parafins that make the hose soft enough to be flexible, out of the hose. The Coast Guard, ABYC, SAE and NFPA with the hose manufacturers got together and created a new SAE standard for fuel hose that was alcohol resistant. Problem solved.
The next problem that became very evident was that alcohol when suspended in gasoline for long periods of time (winter storage) separates out and attracts water. So you get a layer of water and alcohol that are in the bottom of the tank along with various acids that form. In aluminum tanks this eats holes through the bottom of the tank. The recommendation is don't store your boat with fuel that has alcohol in it (almost impossible these days) or use additives called stabilizers and co-inhibitors that prevent the phase separation. The alternative is to store the tank dry, but this is difficult to do.
Along came the EPA and California Air Resources Board (CARB), who mandated the use of oxygenates in fuels. Various ones are used but at the time MTBE seemed the best alternative. In California, CARB mandated the use of MTBE long before the rest of the country began using it. To shorten this, it didn't take long to discover that MTBE was insidious. It could leak out of almost anything you put it in and was leeching into the ground water and was a carcinogen. Also in Alaska where it was used almost year round because of the climate, there were reports of the vapors causing severe headaches and other medical problems.
With all the various additives in the fuel, people began reporting problems with carburetors and fuel system gaskets to the engine manufacturers. Apparently these did not affect fuel injection systems and were particularly evident in Florida, where boats when stored got very hot and fuel vaporized inside hoses and carburetors.
Well, CARB changed their mind in 2001 (I think, could have been 2002) and banned MTBE and the EPA picked up the beat a little later. Now good ole ethanol is the main oxygenate used around the country.
Then about a year and half ago BOAT/US began getting reports of fiberglass fuel tanks failing. Now it's been known for a long time that fiberglass tanks are common on diesel boats but not on gasoline because of problems with gas. Gasoline is a wonderful solvent and will dissolve most anything if left to soak long enough (no I don't recommend you use gasoline as a cleaning solvent) One of the things it works on is polyester resins. Not all. Some are more resistant than others. Epoxy resins are very resistant. But for years I told people who inquired about fiberglass gas tanks simply NO. Don't do it unless you can be absolutely sure that the resin is gasoline resistant. ( I've seen fiberglass tanks that dissolved after six months)
Add alcohol to the mix and now you really have a solvent and with the phase seperation problems and the forming of acids in the fuel it all works on the fiberglass.
The reports are all on very old tanks. Tanks that are ten or more years old, in fact the average is around twenty years old. There has been plenty of time for the fuel to work on the laminate.
Fiberglass is a semi-permeable membrane. In other words liquid will eventually work its way through a glass laminate especially if there is dry laminate or voids, or pockets of uncatalized resins. This is what causes blistering. Well, it also is the reason gasoline can eventually destroy a fiberglass tank.
So you only need to worry about this if you have an old boat with fiberglass gasoline tanks. Most boats have polyethylene plastic or aluminum tanks. It's about 50 50. All evidence to date indicates that plastic tanks are not affected. However, the EPA is going to mandate a much lower rate of permeation from plastic tanks. (gasoline vapor migrates through plastic tanks in very tiny amounts that is currently limited by Federal Regulation but the EPA thinks it is too much) This will result in a change to the compound for the plastic tanks so who knows what will result. A few boats out there have steel tanks or even stainless steel, but they are few and far between. They are not affected by the alcohol problem, but have their own problems.
Sorry fo the long post. I hope this answers your questions.
My dad worked for terry frahs for years and still has his frahs he built while working there , it has had racing fuel in the fiberglass tanks now for 40 years with still not the first problem. cutting up one of these very rare boats would be a big mistake in my opinion because terry was a very smart individual and he knew how to build it right the first time
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