Fuel Tank Repair
We were worried about the condition of the fuel tank in Gone With The Wind. We knew it was the original tank and 16 years old. We also knew it was made of mild steel with a thickness of less than 1/8 of an inch. Worst of all, we knew there was a wet ooze of dirt and fuel residue next to the tank at the bottom of the bilge. We read the article by Bob Haussler in the Fall 1995 issue of BABA SALT. That same issue mentioned on page one that Mike and Sandy Olsen had to cut up their fuel tank to remove it from their Baba 35. We knew we should replace our tank. The boat was not launched in 1996 so we could get caught up on "THE LIST" of work to be done prior to our planned ten year circumnavigation. It was now or never. Or, more than likely, the tank would fail at the worst possible time and place possible. The bottom line is that like the Olsens, we cut the tank up in place to minimize cutting up the boat. Once it was out, we discovered that the tank was rusted about half way through in places on the outside of the bottom. The rest of the tank was in pretty good shape.
When we replaced the tank Cathy was the safety officer at the fire/crash rescue department at Bangor International Airport. She had very strong opposition to our cutting up the fuel tank at all, let alone in our boat. I told her the best method was to use a die grinder with a cutting wheel (a big brother to a Dremel Tool ). She correctly pictured a shower of sparks inside the fuel tank and her opposition stiffened. After much discussion (I once sold used cars), we arrived at an acceptable risk plan. We pumped the fuel out into our new 6 gallon yellow diesel fuel cans with our Par Jabsco "Little Pal Hand Pump. These jugs were later used later to carry additional fuel on deck to extend our motoring range Then we removed the remaining fuel with paper towels. We left the tank inspection plates off for 2 days to allow evaporation to work its magic. We then sprayed engine degreaser into the tank and wiped it up with paper towels. Next, we sprinkled baking soda over the inside of the tank, covering the bottom with the baking soda as a final precaution. Cathy was still concerned that I was about to blow myself and our boat to pieces. I began the first cut, producing a great shower sparks while Cathy sat in the cockpit armed with a fire extinguisher prepared to extinguish the flames in my hair as I blew by. Faithful and helpful to the end! No explosions occurred although this would have been the easiest way to get the tank out. We used the die grinder, a saber saw with metal cutting blades and even our Dremel Moto Tool was pressed into service to make a small cut in an otherwise unreachable comer.
We removed the bulkhead forward of the tank to allow the tank to slide forward. We also removed the shower sump platform to increase the distance the tank could move forward. Next we split the cabin sole along a teak and holly seam. We used a very stiff putty knife and a hammer to do this. The floor is plywood under the teak and holly. This created one large symmetrical rectangular opening from the mast back to the bulkhead of the galley. We then cut out the floor beams, which were not removable from this opening. We now began cutting the tank in half laterally. This cut was made about one foot aft of the forward access plate. We had to cut some of the top away to get tools inside the tank to cut. We raised the forward end of the tank as high as possible to avoid damaging the floor of the bilge when we cut across the bottom of the tank. Once this cut was completed, we removed the forward portion of the tank-. Then we attempted to slide the aft portion forward into the area where the forward portion had been. We were not happy when we discovered it would not fit under the floor beams aft of the opening to slide forward. The upward slope of the bilge floor as it goes forward was causing the tank to come up as it moved forward. This necessitated cutting away some of the top of the aft section of the tank.
We had considered lining the tank with a bladder to avoid removing it. We are very glad we chose to remove the tank. The floor of the bilge under the tank was a mess. There were strips of a rubber like material, which were deteriorated and were a soft sticky consistency. Old fuel, dirt and water had combined to complete the ooze. The entire area under the tank was wet and filthy. We believe part of the problem, which kept the tank sitting in a wet environment results from the bulkheads fore and aft of the tank. I suspect they were intended to keep any leaking fuel contained and not allow it to get to the bilge and be pumped overboard. They also kept the tank from moving forward or aft. They were glassed in place along their sides and bottom. There was a plastic tube running along the bilge floor next to the tank on the port side. The tube went through the forward and aft bulkhead. This would allow any water which got into the bilge forward of the bulkhead, such as water coming down the mast, condensation on the hull etc., to pass through the tank area inside the tube. The tube empties into the bilge behind the aft bulkhead. There was another tube on the starboard side of the tank that drains the forepeak locker. Good idea in theory, but in practice the tubes had become cracked and allowed water to enter the fuel tank area. The forward bulkhead had become delaminated at the bottom and also allowed water to enter the tank area. This ensured a wet environment for the fuel tank. At some point prior to our buying the boat fuel was spilled into this area also. We cleaned it out as best we could but it required steam cleaning to get it really clean and odor free. We cut away the bottom portion of the aft bulkhead to allow access to the forward portion bilge sump. Be careful here, the engine drip pan butts up against this on the aft side of the bulkhead. Cut too high and you are into the engine drip pan! About 8 inches is as high as we could go. Start at the bottom with a small area and you can reach through the new hole and up to feel the engine drip pan. We had never fully understood how this part of the boat was built. Anything small dropped while working under the cockpit disappeared down past the drive shaft, never to be seen again. That goes forward to the aft end of the tank.
Don't forget to mix the resin and hardener for about a minute before adding the filler to thicken it. Just keep adding the filler until you get a peanut butter consistency that won't run. Once the voids are full and you have sanded off any protruding filler you are ready to enclose the plywood in a resin cocoon to keep moisture out. Mix up some resin (stir about a minute to ensure good mixing) with the 205 hardener and coat the top and sides. We used disposable bristle brushes for this. The 205 hardener kicks pretty quickly, especially in hot weather, so your working time is limited with each batch. But it sets up pretty quickly so it runs less on the vertical edges. You can user the 206 hardener if you want more time.
The floor of the bilge drops down to the sump just aft of the fuel tank. Since there was no access to this area it contained everything that had been lost there as well as shavings and scraps from construction days! We took over a gallon container of "stuff" from there. We also found the strainer/pickups for both the manual and electric bilge pumps were upside down. We were so happy to access to this area that we installed the new tanks about 15 inches forward of the original location just to keep this access.
Incidentally, the literature all says the boat has a 60 gallon fuel capacity. Not so! The original tank held 51 gallons. We are positive about that as we had removed all fuel to clean the tank when we bought the boat in 1991. The center portion had no access panel but we removed all the sludge from the rest of the tank. When we refilled it, it would only take 51 gallons. We checked the tank and it was full. The only way to get near the original tank capacity (without tearing up the cabinetry) was to install two tanks. The new tanks hold 55 gallons total. The aft tank holds 21 gallons and the forward tank holds 34 gallons. We actually gained 4 gallons of capacity. The new tanks are also made of mild steel. The thickness was increased to 1/8 inch for the top and sides. The bottom is 3/16 inch. We felt that the extra 1/16 was good insurance. The only part of the original tank with serious rust was the bottom. Even although we feel that the installation methods of the new tanks will prevent rust, we can't see the bottom to be certain. The original tank was less than 1/8 inch thick and survived 16 years in awful conditions without rusting through. With a better installation and the extra thickness, we believe they will last for the life of the boat. After they were constructed with double welds and pressure tested, they were sand blasted to remove the mill scale and dirt. They were painted within hours before any rust could form with Dupont Imron. The tanks sit on interlocking squares of Dri-Dek running under their full length. They will keep the tanks off the bilge floor and allow any water in the bilge to run under the tanks without touching them. We can also flush the area with fresh water if needed by spraying it forward of the tanks and allowing it to run aft to the bilge. The new tanks are held in place by new 1" thick bulkheads which are resin encapsulated and then glassed in place along their sides. They do not go all the way to the bilge floor. That allows water to pass freely under them. The tanks are kept from moving laterally by wedges installed between the tank and the side of the bilge. These are glassed into the corner formed by the bulkheads and the bilge. The reinstalled floor beams sit on the tank in some areas where they do not, pieces of wood bolted to the beams extend down to the top of the tanks. This keeps the tanks from lifting up and added support to the floor. Some of the beams are held in place by heavy aluminum brackets. We removed the old cracked and leaking plastic tubing on both sides of the bilge. We installed ¾" Shields Series 148 white sanitation hose from the forepeak to the bilge sump. Incidentally, the floor of the forepeak was leaking into the area under the v-birth. This was repaired so that all the water coming into this area now drains to the bilge. The hose runs under the v-birth through the old plastic tube until the tube exits the v-birth area. From there the tube was removed . This hose runs on the starboard side of the tank. We tee'd into this with the drain from the shower sump. We don't use the head as a shower. We shower in the cockpit rather than have a soap film all over the teak in the head. It also keeps the moisture level in the boat down. So, it will only drain an accidental spill or , perish the thought , an overflowing head.
Since we now have two fuel tanks we installed a valve in the fill hose under the galley sink. This selects which tank the fuel is going to. We normally put the fuel into 6 deck jugs and pour it into the tanks later using a Baha filter. Most fuel docks don't like us to take the time to filter the fuel through the Baha filter. This allows us to make everyone happy. You'd be amazed at the crud we filter out this way, metal filings and almost always some water. We are quite fanatical about putting only clean fuel in our tanks. We also run the fuel on its way to the engine to a dual Racor filter, which allows us to select the other filter with a twist of the selector valve. Thus, we always have a clean primary filter at the ready. These both have a 10 micron element. They feed a single Racor with a 2 micron filter element which feeds the engine mounted filter. The engine mounted filter is really not necessary now but a major job to replace, as near as I can tell. You will also need to install valves to select which tank is feeding the engine AND to select that tank for the return from the engine. A diesel uses some of the fuel for injector pump cooling and returns the excess to the tank. Otherwise you will be emptying one and filling the other. This can be used to slowly shift fuel from one tank to the other but don't forget and leave it set up that way!
The new tanks are baffled and have access plates which allow cleaning all areas of the tank. The baffles should have just the lower corners cut away just enough to allow fuel to pass to the rear compartment to the pick up tube. Alarge opening under the baffle allows the fuel to surge back and forth and stir up the sludge on the bottom of the tank. The original tank had no provision to clean the center portion. One thing I would do differently is to have a tube on the inside of the tank like the pickups for the return lines to minimize foaming. We have not had aproblem with that but we seldom have a tank less than half full. I read that can be a problem when tanks are nearly empty. Your diesel engine uses about 9 times more fuel for cooling the injectors than it burns. That extra fuel is returned to the tank and can cause foaming if the tank is nearly empty. I had an extra pickup and return installed for future use and promptly used it for our single cylinder diesel powered 100 amp alternator for battery charging that we installed. I think for the slight increased cost, an extra pickup and return port is a good idea. Diesel heaters are another reason for the extra pickup.
DO NOT use the original vent hoses. The original vent hose was ½ inch plastic tubing like that used for water lines. The Coast Guard requirement is USCG approved diesel fuel line hose in 5/8 inch ID. The old hoses are grandfathered but when you replace the tanks, you must comply with the new requirements. Size the new vent openings to fit an adapter for the new 5/8 inch hose.
DO NOT forget to include the height of the studs for the access panels in your measurements. We forgot that and the aft tank began to slide into place perfectly until the studs hit the floor beam! We cut the bottom out of the tank, cut down the sides and put the bottom back on. Of course it had to be sandblasted again and repainted. An expensive oversight on our part.
DO NOT use cork gasket material as we did. It leaks and wicks diesel fuel odor. We found a replacement for it at a heating oil dealer. It is a neoprene like material that they use on home heating oil fuel tanks. It is about 1/4 inch thick. We got ours from Webber Supply in Bangor , Maine. Make certain the bolts will be long enough to accommodate a thick gasket.
DO make certain the tank builder welds 360 degrees around the bolt heads (inside the tank) used to secure the access plates. If not, fuel will weep up around the threads when the tanks are full.
Do consider a separate bolt or two to connect bonding/grounding/lightning protection wires to the tank. A small convience when you remove the access plates and don't have to secure the wires to keep them from wandering off out of sight.
We think replacing the tank allowed us to make signifigant improvements to Gone With Wind. We certainly don't worry about what condition the bottom of the tank is in. It was a lot of work and was not an inexpensive project.
I will answer any questions that you might have about this project. Our e-mail address is BABA35@aol.com. I hope this helps. I have copied some photos from the project which may help envision the process. One picture is worth a thousand words, especially if I am trying to explain something! There are lots of ways to do this project. We did what worked for us. You can probably improve this process to fit your requirements. It is a lot of work but eliminates the worry of a leaking fuel tank. Good luck with your tank replacement.