The Boating Forum - Wait until it Leaks?

The 93 gal. gas tank in my 1981 Grady White was made 4/81 and is 5052 AL. It doesn't leak and appears to be in good shape. Do I wait until it leaks or take the preventitive method and replace it now? 23 years in salt water seems like a long time but if it aint broke.... ;?

keep fishing! if you replace it now you can virtually kiss the season goodby. If you don't replace it and it "leaks" mid season you can kiss the season goodby. ? see the difference? OK good, If you really are a stickler wait till the off season and do it. If you are seriously freaked about mid water explosions than that is a different story. BUt something tells me that if you know the age, material and even thought about changing it, than you would be aware of a leak before it bacame an issue.

just my .02

Actually, it looks pretty easy to replace. The centerline hatch comes out and it's underneath. No cutting. I just removed the hatch and inspected the top of the tank and all looks well, but I can't see below.

When they start to leak is it usually just a pin hole?

Watch the water in your bilge. If you start seeing a sheen or smell fuel, start getting concerned. From what you describe, it sounds like you are better off here in May to get through this season and go ahead and schedule to do it in the fall. BTW, be very careful when you change the tank out. Make sure that once you have syphoned the remaining gas off, you ventilate the tank VERY WELL! A tank of gas vapor is a bomb looking for an ignitor.

Also, might want to do some research on what you will be replacing the tank with. How is it vented, where are the baffles located, does it have the same footprint as your current one, will my level sender fit, etc. :)

I just finished this job on my boat. It's a '90 model 225. I'm not sure if Grady's tank installation method was the same in '90 as it was in '81, but I can't imagine that it would have changed that much. Mine has 2 tanks (a 95 gal & a 55). I removed them both & had them tested. I knew at least one of them was leaking when I bought the boat. My large tank showed some corrosion but was not leaking. My small tank had corroded all the way through & was leaking.

The corrosion on both of them was caused by the same thing, crevice corrosion from strips of rubber sitting against the tank; it just wasn't as bad on my big tank. On mine, the tanks are held in place in two ways. To prevent side-to-side movement, small, triangular pieces of wood are wedged between the tanks & the stringers & then screwed into the stringers. To hold the tanks down, 2x4's are laid flat on top of the tanks & screwed into the stringers. Screwed to the side of each 2x4 is what appears to be a piece of 3/4 plywood cut to about 3" x 21". It's attached in such a way that each 2x4 & plywood strip forms an 'L'. Each of these pieces is situated such that the top of the plywood strips contacts the underside of the removable deck sections. Here's where the problem occurred: between each 2x4 & the tank, there is a strip of rubber. Rubber, being carbon based as I've learned here, can & will cause crevice corrosion if held tightly against aluminum for a long period of time. That is exactly what happened to my tanks. Both of them were corroded where those strips of rubber had been. There was also trace amounts of corrosion at the points where the tank contacted the hull bottom; small pieced of wood are glassed to the bottom of the hull for the tanks to rest on. The rest of both tanks had no corrosion whatsoever. Had it not been for those strips of rubber, they'd have almost no corrosion. Had it not been for the hatches leaking, there wouldn't be any water worth mentioning in the bottom of the hull where the tanks rest.

On my boat, this job turned out to be tougher than it appeared at first glance. There were 3 things that made it difficult. First, it appeared that the tanks, as well as the pieces of wood that held them in place, were installed before the deck cap was installed when the boat was built. Therefore, access to the screws holding these pieces of wood in place is partially blocked by the lip of the deck cap. If you're using a screwdriver bit on the end of a drill to remove them, which I would recommend, your bit needs to be long. Otherwise, the lip of the deck cap will get in the way of the chuck of your drill. Secondly, there was a good bit of fiberglass over-pour that covered some of these screws. This has to be ground away without destroying the head of the screw. Third thing; the hole in the deck cap over the large tank was not big enough for the tank to pass through. It was just barely wide enough but wasn't nearly long enough. The rear portion of the lip in the deck cap wasn't cut far enough back. I had to trim nearly 2" from that section of the lip in order to get the big tank out.

You mentioned that you removed your hatch, but you did not say anything about the support pieces that I've referred to. If your boat doesn't have them, either Grady did change their installation method sometime between '81 & '90 or, the tank was removed from your boat sometime before you bought it. If you don't have these support pieces & the latter turns out to be the case, I would suggest that you install some as they support the hatch. Without them, your hatch will flex & leak. If your boat does have these supports & you simply didn't mention them, then I would suggest removing them in order to get rid of those rubber strips I mentioned. If you can do that before they cause your tank to rust through, the tank may never leak. What I ended up doing with my tank, since I had it out of the boat, was to have it coated in truck bedliner material. Even if you don't replace the tank itself, I'd replace all the rubber hoses if they're original. Mine were very hard & brittle. Also, I'd make this an off-season project. I'm sure it's way easier than dealing with a foamed in tank, but it's harder than it looks. One last thing: I went back with Armstrong deck plates to cover the round inspection ports. The pop-out type that the boat came with were leaking badly.

Good luck.

M-keith,

Thanks for the reply. It sounds like my tank is installed exactly as yours is. I guess it looks easier to remove than it really is. Mine too, has the cross members and after reading your detailed reply and looking closer at mine, I can see it won't be a cake walk to remove. The cross members do look like they were put in before the floor was installed and may be a problem to get out. The tank does look like it will fit nicely through the existing hole. I think I will just keep an eye on it and wait until this winter to maybe tackle it.

Where did you get your Armstrong deck plates?

Thanks again.

I bought the deck plates direct from Armstrong. Here's a link- http://www.armstrongnautical.com/Brackets.htm

You're correct in that it won't be a cake walk, but it's not insurmountable. One more thing: My tank looked like it would fit through the hole in the deck just fine, but it was a different story when I actually went to pull the tank out. So, the guys that I had come over to help me pull the tank ended up sitting around while I was grinding fiberglass. I should've measured first.

colliwh - 5/25/2004 8:32 PM

Watch the water in your bilge. If you start seeing a sheen or smell fuel, start getting concerned.

I had a buddy that had the opposite problem. The tank on his 197X Whaler got a couple of pinhole leaks in it....one he said looked like it might have been started from the tip of a phillips screwdriver and corroded through from there.

But his symptoms were that he kept getting water in his tank....a *lot* of water. Apparently rainwater would get on top of the tank and drip into the tank through a couple of holes. Never saw any fuel above deck or in the bilge.