pulled up the deck..

[finx]

I finally got to the gas tank. I had to rip up the deck and hand dig out the gas tank through the foam.

After replacing the stringers do I have to encase the gas tank in foam? I would like access to it later on in case of repairs or modification.

Will not filling the gas tank area with foam and creating an accessible hatch be an issue if it was previously foamed and nailed shut? Thanks!

 

[tpenfield]

Re: pulled up the deck..

Aluminum tank??? IF so and, If the old foam was wet, you should check the tank for pits and corrosion. If you foam in the tank upon re-installation, it is sides and bottom only, the top needs to stay clean.

Lots of folks do not foam their tank in upon re-installation, opting for other means of securing the tank. Foam is best for securing the tank and adding structural strength to the boat. However, it can be problematic, if the foam gets wet.

 

[finx]

Re: pulled up the deck..

I cant tell if its aluminum or stainless steel. I cant tell. Could you in a picture? Its very light.

There was gas EVERYWHERE. I was getting lightheaded taking the foam out there was so much gas. There is a leak but I couldnt tell form where. Stringers were soaked in fuel. I smell like a gas station.

Thats why I got to thinking about when I'm done leave it an open hatch for repairs just in case.

 

[jigngrub]

Re: pulled up the deck..

A fuel cell below an enclosed/inaccessible deck is a very poor design, I'm sure you can come up with something much better'

An access hatch over a containment box with security tiedowns would be the way to go I would think.

 

[finx]

Re: pulled up the deck..

great minds think alike! That's exactly the route I was going to take.

Can I put a garden hose in my tank and fill it up without causing damage? I would like to see where the leak is. Hopefully its at a hose. The tank looks like it's still in good shape. Looks can be deceiving though.

 

[JDA1975]

Re: pulled up the deck..

have the tank pressure tested, it would find the leak if there is one and assure you that it still meets specs before reinstalling. It shouldn't cost much to have done if you don't have the equipment to do it yourself!

 

[finx]

Re: pulled up the deck..

I was reading and other people used 3-5psi to test their tank. I dont want to ruin my tank by blowing out the welds as this tank will cost me 200-300 to replace. I'm a boater on a budget.

I will fit my tank with the correct fittings to put pressure in it. Maybe I'll hook up a bicycle pump to it and do it by hand. Any precautions I should know about? There is no gas in it. The gas that leaked out was 10 years old. I tried setting a small piece on fire away from the boat to see if its still flammable and its not.

 

[jigngrub]

Re: pulled up the deck..

have the tank pressure tested, it would find the leak if there is one and assure you that it still meets specs before reinstalling. It shouldn't cost much to have done if you don't have the equipment to do it yourself!

+1 on the pressure test.

 

[JDA1975]

Re: pulled up the deck..

there should be a plate on your tank, will list capacity, date of manufacture, etc, and should also state "pressure tested to X PSI in accordance with some law digits" pressure test to that PSI, or if you cant find a plate run 3 PSI. as long as you dont overdo the pressure you shouldn't blow your weld, if you do then thats the problems we were looking for before reinstalling. be sure to leave it pressurized overnight, it should maintain its pressure over an extended test, if it bleeds off, you either did not connect it right or it has a leak

 

[finx]

Re: pulled up the deck..

Awesome, thanks! This is why I love this forum. I'll stop by auto zone and get some hoses with metal screw wraps to get it to seal.

This got me thinking. Could I also create another storage compartment outlined in blue? How much structural support does foam give? Could I just double the amount of plywood used in that area and keep that hatch open as well for storage?

 

[tpenfield]

Re: pulled up the deck..

I was reading and other people used 3-5psi to test their tank. I dont want to ruin my tank by blowing out the welds as this tank will cost me 200-300 to replace. I'm a boater on a budget.

I will fit my tank with the correct fittings to put pressure in it. Maybe I'll hook up a bicycle pump to it and do it by hand. Any precautions I should know about? There is no gas in it. The gas that leaked out was 10 years old. I tried setting a small piece on fire away from the boat to see if its still flammable and its not.

The odds are strongly in favor of their being a leak, based on the gas found in the foam, etc. The tank is most likely aluminum, as Stainless is not allowed for gas on boats (for some reason ???), but more probably, stainless would be wicked expensive.

I just had a new 85 gallon tank made for my boat . . . $1,000 . . . but if you can find an 'off-the-shelf' tank that will fit, then you should be a whole lot less.

Before you pressure test it . . . do a couple rinses and purge with a strong detergent to get rid of the fumes, and the related explosive hazard.

Usually, aluminum tanks, once they start to grow holes, there is no telling how many more are in process. So, it is best to start with a new one.

 

[finx]

Re: pulled up the deck..

do aluminum tanks typically start to erode from the inside out or the outside in?

 

[tpenfield]

Re: pulled up the deck..

do aluminum tanks typically start to erode from the inside out or the outside in?

Both directions . . . then they 'meet in the middle'. The issue is when water stays in constant contact with the aluminum, corrosion sets in. This can happen on either side of the surface.

There is a fair amount of documentation/articles on the web about aluminum tanks, installation procedures, etc. It sounds like your tank may not have been installed properly, however, tanks are only going to last 15-20 years . . . thereafter it is pot luck.

 

[Georgesalmon]

Re: pulled up the deck..

As above. Also when you pressure test mix up some dish detergent and water in a spray bottle and spray everything, all the welds, seams, fittings etc. Don't go over 3psi, if a tank full of air blows even at 3psi you'll remember it for the rest of your life. As they say, "been there, done that"

 

[finx]

Re: pulled up the deck..

I decided to clean it off and rinse out the insides with water before I did a pressure test. I found a small hole which would explain the insides of the boat filled with fuel. I tapped my screwdriver on it and it poked through easier then butter. I guess I have to bite the bullet and buy a new tank. Unless I can make one myself. Is there a reason I have to use Aluminum and not steel or maybe stainless? I could weld my own!

 

[TruckDrivingFool]

Re: pulled up the deck..

Why aluminium? I'm going to guess weight savings.

 

[Georgesalmon]

Re: pulled up the deck..

You should really buy one. Yes you could make one, but the reason they cost so much is not the materials and labor. Its the liability insurance gas tank manufacturers pay. When gas tanks leak people could die.

 

[rickryder]

Re: pulled up the deck..

Try craigs list and find a good used one

 

[finx]

Re: pulled up the deck..

Thats a good point. This might not be an area where I want to experiment and learn how to weld.

that being said, If I buy a new gas tank, it wont be the exact same measurements. I can try to get it close but I wont get exact.

Does it matter if it sits a little higher or lower in the hull?

What about if the hose feeding fuel to the engine sits a bit lower or higher. Does that matter?

It doesnt have fuel injection as its so old.

 

[oops!]

Re: pulled up the deck..

as long as the new tank is below deck height with the fittings.....you are good.

just make sure there is clearance for the sender and input hoses.