Replacing Fiberglass Fuel Tanks

[BradV]

Hi everyone I'm taking on the project of replacing my fiberglass fuel tanks in our 1972 Hatteras 43 DC. Sourcing ethanol free fuel has become to much of a pain and we have decided to make the switch. I have a few questions for the community and any input is greatly appreciated.

Any ideas on how to pump the gas out? We rigged a car inline fuel pump with a hose going in the fuel tank and the out into gas cans. This however was taking forever. Does anyone else have an idea that isn't extremely expensive but would get the job done quicker?

Also we have been told the easiest way to remove the tanks from the boat is to cut them. We were planning on filling the tanks with water (once all the gas has been removed) to get the highly flammable fumes out and then cutting the tanks with an air tool. Someone recommended a pneumatic saw of sorts so no electricity would be used preventing a spark. Any other ideas or precautions we should be taking?

Finally has anyone replaced their tanks and if so who did they use to make them? Im on a budget so I was thinking of going smaller than the current 200gal tanks (total of 400gal) as we don't travel very far just from Chicago,Il to Holland,Mi. I was thinking anywhere between 100galls to 150gallons each would work for us. Any used tank ideas or is it better to get new custom tanks? I'm hoping to keep the cost of the tanks around $2000 if that is even possible.


Thanks in advance for everyone's help and input!


Here are some pictures of what we have finished so far.

 

[TROUBLE]

have you thought about using the aft holding tank?

Art

 

[Timeout]

How 'bout just going for a boat ride

 

[smoothmove]

Just to be sure.... Is this "Castaways?" If not the coincidence is nothing short of remarkable.
Eric

 

[bobk]

Have you considered taking off the top and re-glassing the inside with an appropriate resin? I know a guy who did this and two years later it was still holding up OK.

Bobk

 

[rwetherington]

I would do SS tanks if i where going to replace them. Make sure everything is bonded correctly and tha you come up with a way secure the tanks not just a strap across them. Remember this that your engines and not going to like the change or to the new fuel. So be prepared to spend money on them in about a year.

 

[gbharrington]

Non ethanol "recreational"gas is becoming easier and easier to find. The work and expense of replacing the tanks just doesn't seem worth it. I suggest that you seriously reconsider.

 

[rwappleton]

I considered a boat that needed tanks before we bought our Diesel.

This is a great time to move the beds to a center Queen and place the tanks under the bed like the newer models. You can do the project using smaller (and less expensive) tanks either in the original locations or center. There are several options of materials that will handle the crummy gas. The big factor for me was getting the tanks in without slicing up the boat. there are bladders available that you can build a box for. They will custom build them but are more pricey than tanks.

I too was going to rinse the tanks with alcohol then fill them half full with water. The alcohol will mix with the water. Also lots of ventilation.

If the tanks are allowed to set open for a week or so fumes should not be a problem. My plan was manually cutting small holes in the top of the tanks with a air powered saw (harbor freight) and let them set for two weeks.

My budget was 3000 and it looked like I was going to be 400 under budget with a finish carpenter doing the finish work.

Good luck with your project and keep us advised of the progress!

Russ

 

[SeaEric]

Why not cut the tops out of the FG tanks and fit the new tanks inside? You could perhaps foam them in there.

 

[TROUBLE]

that sounds like a great idea

 

[rwappleton]

That was one of my bladder options and will work well. Also slightly smaller tanks inside the originals will work. The top is cut off and the baffling cut out also.

 

[SeaEric]

From a functional standpoint, bladders would be good as they don't have any air in them to form condensation. No condensation with ethanol fuel would be a good thing (sorta like box wine is technically a good idea).. I just don't much like the idea of gasoline in a bladder.

 

[RT46]

how about putting dry ice in the tank once you drain the tank?
as the dry ice melts it will displace the air required for combustion.
Ive never done this but im told it works, make sure you have air to breathe if you do this.

be very careful when cutting and removing a gas tank, even static electricity can cause an explosion if the fuel air mixture is just right.

A whole marina burned down in Freeport NY about a year or two ago when the yard was removing and gas tank from a boat. Two workers were seriously burned in the incident.

Also, make sure you only use ignition protected pumps to remove the gas and store it in approved containers.

 

[saltshaker]

I did this many years ago in a 36ft Trojan. Those tanks were galvanized steel so we needed to be very certain nothing would spark when we cut them. The galvanized coating was shedding so my tanks needed to come out. I bought an inexpensive fuel transfer pump and a couple of plastic 55 gal drums. We pumped the gas out through a filter to clean it the best we could. This helped getting rid of it as the marina took it from me and used it for some of their yard equipment that was a bit more forgiving of poor fuel. After that i ran water and dish soap through then a few times until they seemed clean. I then hooked up a bilge blower to the tank fill to exchange the air in the tank. I let this run most of the day. Worked well for me and we had no issues. My new tanks were made out of aluminum. We choose aluminum for a few reasons. At the time we couldn't build a stainless tank large enough and get a CG certificate for them. Stainless is more rigid and there was a limit to what size each tank could be. My brother in-law builds fuel trucks and he preferred working with aluminum. We built cradles for the tanks and lined them with neoprene to avoid any possibility of water being trapped between the tank bottom and the floor. The tank fills and vents were welded aluminum pipe. We also used aluminum chain for the safeties on the fill caps. Aluminum is a great tank material but all it takes is on screw or chain of dissimilar metal to corrode a hole in the tank.

You have good access to your tanks and may be able to repair them or use them to hold a bladder like others have mentioned. I like the idea of moving the tanks and building a new queen bed. There are a lot of options and issues to deal with that are specific to ethanol and fiberglass compatibility. Talk to someone who is familiar with this and has done several tank refits. They should be able to guide you. There are a few here that have done it, hopefully they'll chime in.

 

[rwappleton]

Bladder technology has changed dramatically over the past several years (read safer and cheaper). Installation has to be careful as chafing in the box or retainer will cause problems. Bladders have been in aircraft since the 60's were used in Corvette's in the seventy's and used in several places today.

 

[BradV]

We got the tanks freed and the gas pumped out.

 

[BradV]

 

[saltshaker]

Now would be a great time to replace those copper lines running along the hull. I'm guessing you can't get to them so easily when the tanks are in place. I'd check the exhaust tubing to make sure there aren't any thin or porous spots.

 

[jim rosenthal]

Now would be a great time to replace those copper lines running along the hull. I'm guessing you can't get to them so easily when the tanks are in place. I'd check the exhaust tubing to make sure there aren't any thin or porous spots.

Those are the steering lines, I think. I agree. This is a "while you're in there" that is well worth doing. Hynautic sells a high-pressure nylon tubing that might work well for this.

 

[gbharrington]

Now is also a good time to repack your rudder shafts as you can actually get to them.