Correct way to install gas tank?
 

Should you use the pourable foam to "lock" in the tank? Or should it be set on plastic stips and 5200 to a deck between the stringers? I've heard the foam causes corrosion on aluminum because it doesn't allow air to flow around the tank if it ever gets moisture. But just setting the tank on some strips with 5200 and not filling the voids on the sides sounds like the tank could shift. Any info or experiences? Also anybody know of a tank builder in the jersey area?

Re: Correct way to install gas tank?
 

I'm not sure how often this subject comes up here , but over on the Donzi.net it's been hashed about a thousand times and it can get quite emotional sometimes. :rolleyes:

How was the original tank installed ? Sometimes it is possible to remove a foamed in tank and install it in a way that concerns you less as far as corrosion goes.
The key is , that no matter how it's installed it must be epoxy barrier coated in some way. That's nine tenths of the problem beaten.

Tanks that are foamed in are MOST UNLIKELY to ever come loose and fly around .. they also are supported evenly all around.These are two critical issues. If the original was foamed in and it is possible to now install the new one in a different way , even support ,particularly on the bottom of the tank is very important. I'm not a big fan of tanks with 'tabs' on them bolted to stringers etc Fiberglass likes to flex , metal does'nt.

If you resort to foaming back in just make sure they tank is epoxy barriercoated (a guy over on the Donzi net did a websearch and found an excellent epoxy tar material) and use foam with a 4lb density.
Steve

Re: Correct way to install gas tank?
 

The original was foamed in but not coated. Moisture got in and never dried causing the aluminum to pit up. The tank does not leak but has some pretty bad pitting. I guess I could epoxy coat the tank and foam it back in but the pitting has me a little scared. If a get a new one made I will coat it and put a support under it and then foam it in.

Re: Correct way to install gas tank?
 

I'm at the same point you are. The tank is .125 aluminum 150 gal., 7 1/2 feet long. My idea is to form four 1/4" thick 3" wide stainless steel strips to the same shape as the bottom of the tank, add 1/8" polypropolyene strips between the tank and the s/s strips, bond all of it together with 5200, and bolt the s/s strips to the stringers next to the tank. I don't see any good way of keeping foam from soaking up water over the years. I wonder if the hull needs the extra support of the foam and tank to keep that large area from flexing? I'd love to hear what you find out!!!!! :evilb:

Re: Correct way to install gas tank?
 

KAAMA, after thinking about it I came up with getting the tank Rhino Lined (like a truck bed). I will then pour some foam and set the tank. Once the foam rises I will pour more down the sides and cut off any excess. I figure this way you get the best of both worlds, water tight because of the Rhino and solid because of the foam. I'm also going to Rhino Line my floor once I put it back in, maybe red or yellow :D

Re: Correct way to install gas tank?
 

SP Sheetmetal in Toms River. They make great tanks and they are local. Follow thier instructions or take it to one of the shops they recommend. Like mine :evilb:

Re: Correct way to install gas tank?
 

Catagory, thats who I had in mind.

Re: Correct way to install gas tank?
 

S & P Sheet Metal? They still in business, and still building fuel tanks?
They're located on RT 37 near Fisher Blvd. right?

My Dad's machine shop (in Toms River) used to do a lot of business with them back in the 70's. I made many trips to pick up formed parts.

Re: Correct way to install gas tank?
 

One and the same. They have new owners since the 70's but they are still in the same place and still doing a nice job with fuel tanks. I use them exclusively.

Re: Correct way to install gas tank?
 

I think you're on the right track here !

I picked up some good advice from an 'old timer' before I did mine and he strongly advised to do multiple small pours .
The foam has a lifting capability of (I think) 6lbs per sq inch when firing off , so weight the tank down very firmly and do a couple of small pours underneath from different sides one at a time. Once they've gone off you can do the sides with no worry.

After I trimmed the top of the excess foam I heavily coated it with a flexible epoxy coating to prevent water absorbtion from the top. Because of it's location it will be many many years before water affects the bottom part of the foam.

Re: Correct way to install gas tank?
 

That Rhino lining coating the tank seems to be a good idea! I'm gonna call around (wellcraft, outerlimits, etc.) to see if my strap idea is still usable. :evilb:

Re: Correct way to install gas tank?
 

I removed all the wood stringers and bulkheads and transom. The foam allowed water to get to all the wood and rotted them. One section of stringer was 3/4"X 12"X 8' and it weighed 50 lbs from all the water weight. The gas tank was set on 1/4" X 2" X 12" HDPE and glued to the hull. The stringers were custom fitted to the gas tank with wood blocks screwed to the stringers to hold the tank in place.

Once water gets into a foamed in compartment it will never dry out. I'll never use foam in a boat.

Re: Correct way to install gas tank?
 

The way we install most tanks is.

The tank gets epoxy coated by the tank builder and has bolting tabs welded to the tank to fit to the stringers.

The bottom of the tank is built to fit and be supported as evenly as possible on the inside of the hull.

Use strips of neoprene rubber gluded to the tank with the correct mastic, NOT 5200. Make sure the strips are placed in such a way not to trap water and use the mastic to around the edge of the strips to create a bevel so no water gets trapped on the hard edge.

Make sure the tank is resting flush (no rocking, no hard spots). Drill and tru blot the mounting tabs to the stringers.

If the hull shape allows you can place some PVC from the front bulkhead to the rear bulkhead limber holes under the tank and make sure it's sealed at the bulkheads to allow water to run from one compartment to another under the tank.

It's a cost effective and secure way to go. If done correctly you shouldn't have any water issues. If I can find them I can post some pictures.

It's late and been a long day. I hope this makes some sense and helps.

Re: Correct way to install gas tank?
 

I called Wellcraft and talked to an engineer. He said my stainless strap idea would put way too much stress on the tank. He said to foam it in, and to keep it from being pushed up while pouring, have a board in the front and back clamped to the stringers holding it down. Fountain is also foaming the tanks in. Catagory 5's way w/the rubber seems good- no foam to soak up water. What kind of adhesive (mastic) do you suggest? Cat 5, I'd love to see those pics if they are handy! :evilb:

Re: Correct way to install gas tank?
 

Yes,
that response from Wellcraft does'nt surprise me at all...even support is critical.

The problem we are now experiencing , I believe , stems from the fact that the tanks were never properly coated for the long run rather than actually being foamed in. Admittedly , wet foam can be a PITA for stringers that may have been glassed over in a questionable way , but it was'nt in my case (luckily).

It would be good to see some pics to clearly understand what Cat5 is referring to.

Re: Correct way to install gas tank?
 

I'll dig them up tomorrow and post them late tomorrow night.

Re: Correct way to install gas tank?
 

I am one of the Donzi Nets emotional tank guys, there a arguments in several directions. Most of the noise about the tanks was about un-coated tanks that only lasted 20-30 years. My new tank was Chromated to death and had two coats of Epoxy tar and yes foamed which makes it part of the boat. I wish I had had the fore thought about Rhino Liner which was brought up on the D board and here, I have in and on my truck that would be the ultimate coating.

Phil

Re: Correct way to install gas tank?
 

Use 4lbs foam it is way supirior to the 2lbs used by most manufacturers.

Re: Correct way to install gas tank?
 

Thanks Cat5 I'm looking forward to those pics!! :evilb:

Re: Correct way to install gas tank?
 

sorry thought i had some better pics but hope these help.

We did not order this tank so I was not happy with the fit you might notice the shims on the one side. This was the only way we could get the tank to sit and be evenly supported.

Re: Correct way to install gas tank?
 

Some other tank install types but the rubber on the bottom is all the same idea. Even if you foam in the tank you should use the rubber. The foam does not really support the tank's weight.

Re: Correct way to install gas tank?
 

another one tank that is strapped in place but again the rubber is done in the same way.


Befor and after

Re: Correct way to install gas tank?
 

Thanks for the pics Cat5. I see what you were saying. :evilb: