4207 Fuel Tank Replacement

[Lee_B]

Looking for some advice.... Just purchased a 1989 Carver 4207 with 3208 Cats. It has a bad fuel tank on the port side and my plan is to replace the tanks on both sides. Anyone on here have any experience/advice on the best way to proceed and/or things to avoid?

Thanks,

[Viper]

Welcome aboard Lee.

That's a big undertaking. Been a while since I've worked on a 4207 so I may be mistaken here but I don't think that those can be removed without moving the engines first. Perhaps Waybomb can confirm as he had a 4207 in the past. Pretty sure the tanks tuck under the decks or at least under the side cabinet compartments so I don't think simply pulling up the cabin floor port and starboard will allow you to pull them straight up unless they're only under the cabinets and dismantling those will allow you to pull them up and out.

Have you tried contacting Carver with your hull number? They may be able to offer up some recommendations. You can also ask them who the tank OEM was (probably not around anymore) but there should be a label on the tanks with that information. If you can find a manufacturer that has the drawings for those tanks, that would be the best way to go. One that deals with a lot of marine tank builds might have drawings from either the original OEM or recent builds.

Is it leaking from the bottom of the tank?

Keep us posted.

[waybomb]

The only way the tanks are coming out without pulling the engines is cut the hull side open.

It's not a bad way of doing it.

I've seen it done a few times on 53' Hatteras flush decks to get the old Detroits out

[Viper]

Thought of that Fred but you think that would cost less than removing the engines? Wouldn't necessarily need to haul the engines out completely, just lift to clear the pan and move an engine aside one at a time. Will be costly either way.

[waybomb]

The stringers are tall. I don't think you'd be moving the engine over far enough to get the tank out.

But then again. I never did it

Definitely need more due diligence on this one.

[bud37]

Welcome to the forum....... We looked at 42 Chris and found out afterwards the tanks had been done by cutting the hull sides and it was gas. Couldn't tell afterwards. Thing about the diesel tanks , they can be cut up in the boat, but the new ones have to get in somehow. There are some creative people out there that do this kind of work...

[Lee_B]

Thanks for the welcome and all of the replies. My intention was to pull one engine at a time and stack it in the salon on the opposite side. I plan to add support under the salon deck and add dunnage to spread the load. I considered the hull cut, but am concerned about doing that with the cored hull. The advantage of the engine pull is that it allows me to do all the deferred maintenance to the gears and the outboard side of the engines - and the bilge areas. Thanks Viper for the suggestion to call Carver for information... My last boat was a Present Yacht, so that was never an option. It's hard to tell where the leak is, I caught it during the survey/sea trial (fortunately). As best as I can tell it is toward the bottom of the tank and at this point is just a weep. The problem seems to be the way the tanks are installed. There is a cofferdam that the tanks sit in without any limber holes. There is only about a 1/4" clearance between the tank and the side of the cofferdam, just enough to keep the tanks in a water bath for the last 30 years. My best guess is the water is either from the tanks sweating or from spray through the engine room vents. Right now it appears that one of the biggest challenges will be getting the tanks out, cutting them up may be the only solution. My plan is to stay low on fuel this summer and if necessary transfer all the fuel to the starboard side if I can't mange the leak with diapers. Right now it doesn't appear to be leaking more than a cup of fuel every few weeks. I would like to get some use out of her this summer and haul in the fall and begin the project. That gives me the summer to get my ducks in a row. I will update as I go and appreciate all the input I can get!

Thanks again,

[Viper]

While not a permanent solution, look into what it'll take to epoxy the bottom of the tank internally. I've heard of companies that provide this service with the tanks in place. It should give you a leak free window of opportunity to get things ready for a couple of years.

[Hugo]

If you can identify the source of leak and access I would try and repair that first if possible from outside (ideally) or inside of tank. Who knows, might last another ten years...

Another option would be to open top of tank up (if accessible) and build another tank inside the existing tank. Just aluminum and welding... The panels can all be measured and cut outside the boat. I've heard of this done before.

[Lee_B]

The biggest problem (and expense) with this job is going to be getting access to the tanks. They are saddle tanks mounted outboard of the engines with very limited clearance. There may be 12" between the engines and tanks and maybe 8" from tank top to the under side of the main deck. The epoxy solution is interesting, I'll need to dig into that one a bit - my main concern is adhesion to tanks that have held diesel fuel for 30 years. For now I will continue to explore my options and monitor the leak to see how active it is. In the mean time keep the suggestions coming, the solution is out there somewhere!

Thanks,