"Bulkhead" between Fuel Tanks

[jmain]

Hello,
We just got a 1996 Marlin 30 that needs a little love, so this will be the first of many stupid questions that I will ask!
The Bulkhead/spacer that is between the two fuel tanks is totally disintegrated. (It is the thin board between my feet in the photo below.) It is glassed in to the stringers on the sides, but doesn't appear to be structural. It also does not appear to be in contact with any other wood.
I am sure it is there for a reason, but should I be worried about it?

Thanks for your input.

 

[seasick]

I would guess it is there to prevent the two metal tanks from rubbing against each other and possibly also there to locate the tanks during assembly. I would install some sort of spacer if the old panel is removed. Don't use rubber.

 

[Hookup1]

I agree with SEASICK on the spacer. That deck hatch is likely compromised. That "goo" on the top of the tanks looks like plywood glue. Did you get any drainage from it when you stood it up?

 

[jmain]

Thanks, @Hookup1 and @seasick.

So, I finally got to get back under the floor again this weekend... but for a different reason. When I filled up the main fuel tank (for the first time), there was a small leak. I thought it was the gasket at the fuel gauge sending unit, so I replaced it. The next time I filled it up, it was still leaking. Long story short, I have a couple of corroded spots under the floor support just forward of the fuel gauge sending unit. Most are superficial, but one was all the way through and was about the size of a pin head. So, I patched all of them with JB Weld for aluminum fuel tanks. I also cleaned the entire area as well as I could to remove all the mildew/grime/goo. The only place that there is any corrosion is where the rubber under the floor support touches the aluminum.

The reason I say all this is to get back to @seasick's comment on not using rubber in between the fuel tanks. Is the corrosion the reason, or is there another reason?

Obviously, that part of the bilge hasn't been cleaned for at least a decade (if ever) by the previous owners. Rubber against aluminum by itself shouldn't be a problem, as long as it is maintained/cleaned on a somewhat regular basis, or Grady wouldn't/shouldn't have used it.

 

[Uncle Joe]

I have replaced a few tanks in my Grady's over the years. My sincere recommendation is to replace the tanks now, while you are at it because you will have continuing problems down the road. Those tanks are at the end of their useful life (25 years) and you will end up with a bilge full of fuel sooner or later. I would also replace that "spacer" with marine grade plywood at the least.....coated with resin, even better. Be sure not to block any area intended to be clear for flow in the bilge.
Sorry to be a downer but those tanks aren't going to get any younger.

 

[jmain]

I have replaced a few tanks in my Grady's over the years. My sincere recommendation is to replace the tanks now, while you are at it because you will have continuing problems down the road. Those tanks are at the end of their useful life (25 years) and you will end up with a bilge full of fuel sooner or later. I would also replace that "spacer" with marine grade plywood at the least.....coated with resin, even better. Be sure not to block any area intended to be clear for flow in the bilge.
Sorry to be a downer but those tanks aren't going to get any younger.

I completely agree, @Uncle Joe. I patched the hole and corroded areas, just to get me through the summer. Even if I don't use the main tank anymore, I didn't want that little tiny vent filling the bilge with fumes. Not looking forward to the $$$ of replacing both of the tanks. If you have any lessons-learned from replacing your tanks, I'd appreciate you passing them on.

 

[seasick]

Rubber has carbon in it and that in conjunction with salt water ( or just moisture) can lead to corroding of the aluminum. There are better option for the spacers.

 

[Uncle Joe]

I completely agree, @Uncle Joe. I patched the hole and corroded areas, just to get me through the summer. Even if I don't use the main tank anymore, I didn't want that little tiny vent filling the bilge with fumes. Not looking forward to the $$$ of replacing both of the tanks. If you have any lessons-learned from replacing your tanks, I'd appreciate you passing them on.

JMAIN.....my Offshore is configured quite differently than your Marlin so I don't know what I can add. I was able to pull my tank....make a sketch for a quote from a fabricator and then bring in the old tank for the welder to use as a template. Not much to re-installing......teak wedges....neoprene strips.....replace hoses...good to go. The filler hose was the worst part but they have been known to dry out and split so I would do that as well. use the old hoses to pull the new while the tanks are out.

BTW......a 93 gal aluminum tank cost me about $1100 from a fabricator on the South Shore of Long Island.

SEARCH "Fuel Tanks" on this site and you will find lots of threads and pics that may help. Don't worry....the job looks harder than it really is. Good Luck!