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Do the original 31 fuel tanks have fiberglass lift rings built into them on the aft end? It's a gas powered 1977 bahia mar. Trying to determine if the fuel tank is original or not - it's 222 gallons, fuel pickup for engines is in the rear of the tank, has a fiberglass "twist" on the rear top edge that appears to be a lift ring, and the current owner (owned her for 4 years) does not know if tank is original or not. She's in fantastic shape - very well taken care of - which leads me to wonder if the owner prior to the current one replaced the tank (the cockpit decking is glass over wood core, but the supporting structure underneath looks almost brand new - sealed mahogany). I should have taken a picture yesterday.

I have a feeling it is original, but with 5.7% ethanol here I'm not sure how well it would do.

They do have a lift ring. From the description it sounds original.

Farside,
If it has the fiberglass eye lift ring it's an original tank, another way to see if it's original is a printed tag glassed over on the top of the tank near the fuel line pick-ups.
Tag might be painted over, the tag has the date of manufacture, capacity, and some say not for use with methnol blend fuels. The 222 gallon tanks were not made until after 1971-1972, and the original deck supports were Phillipine mahogany thru bolted to the tops of the 4 stringers.
Another way to tell if it's original is if the fuel shut off valves have small thin thumb style valves with a round fluted valve top made out of brass with flare fittings it's original. Check to see if the fuel lines are alcohol resistant A-1 USCG rated hoses, if not the tank is more than likely original and they need to be changed for new resistant lines.

Pete

Tony and Pete:

Thanks for the information. That confirms my suspicion - it does seem to be original (fuel lines too). I did not see a tag, painted over or otherwise, but I did see a location where a square tag may have been removed from (paint looked different if you know what I mean) near the fuel pickup lines.

I take that 5.7 ethanol is still bad for the original tanks, it just slows down the degradation due to the lower concentration?

Thanks,
John

Mine originally had copper lines. Changed those when we repowered.

The tag is probably gone. Mine came off during the two years she was open due to the repower.

Ethanol will eventually kill the tank.

Many years proceeding mandatory E-10, as winter approached us here in NYC our gas stations and fuel docks changed over to a Winter Blend, better known as "Oxygenated Fuel". Fuel pumps were marked" Oxygenated Blend, may contain up to 10% Ethanol".

I ran for many winters on this stuff....my tank did survive through many years with some amount of Ethanol in the tank. What may have been the saving grace for me...I never expected to stay in real late...so as I used the boat I kept topping it off. So even if the dock was pumping a full 10% Ethanol, it was being diluted by the fuel in my tank. Then again many boats didn't run late in the season so I'm not sure how much of this blend the fuel docks were taking to begin with.

I got my first full dose of pure E-10 into an emtpy tank as I ran in from a great day of fishing just to get enough fuel to go back out and fish some more...I ran in with boat performing flawlessly, took on 30-40 gallons and could not get back out of the harbor as one motor just started sputtering...it was that quick....but I got back to dock and was still able to run to some degree for the next two seasons.


So to answer your question, I don't know. Sorry...My thought is if boat is in such great shape...buy it with money budgeted towards a new tank and install. If you start to have a problem switch it out...if you don't I'm sure you'll have a way to spend the allotted funds.

Someone here on the board says he has been running E-10 for a couple years on his original glass tank without a problem. Capt Dick Dean comes to mind...but I could be wrong.

every tank I have seen has the glass twist lifting ring, and everyone broke long before the tank came free

sim, Raybo, Tony, and eveyone else:

Thanks all for the information. Very useful to me.

I am approaching it with the intent to replace the tank. Curious, since it's a Bahia Mar model when they remove the cockpit to replace the tank does that mean the whole cockpit as in up to the helm? I did not see an seams aft of the engine covers.

I've seen quite a few pictures on some 31's (bahia's and others) where the cockpit looks to be 3 pieces (length wise) - Is this the cheaper approach to replacing the tank than taking the complete cockpit out? I would imagine the the support beams under the cockpit decking that run width-wise would have to be reworked completely. Or am I over thinking this?