Leaking Fuel Tanks (continued)
Date: December 23, 2015
From: Paul Uhl
Aluminum is the preferred material for fuel tanks and is what Endeavour used on all their boats. The boating industry preferred them because aluminum lasts a long time, is rigid and doesn't flex which increases their longevity, have baffles which reduce sloshing and increase the rigidity of the tank, and don't swell and leak like plastic tanks do. The primary issue with aluminum tanks, as some of you know first hand, is of course corrosion—but this is not exclusive to Endeavour sailboats.
ANY boat (sail or power) with aluminum tanks will corrode if it is continuously exposed to water WITHOUT exposure to air.
Saltwater is particularly corrosive and will speed up the corrosion process. Also, aluminum fuel tanks that are foamed in place (a practice many boat builders continue to use even though industry standards do not allow it) will also hasten the process because it allows water to be constantly trapped against the side of the tank. This occurs from the the tank expanding and contracting from heating and cooling while the foam stays in place, and creates small cracks and separation between the tank and the foam.
However, if an aluminum tank is properly mounted allowing good ventilation on all sides of the tank—including the bottom—it can last pretty much forever, and the only corrosion that will occur will be the harmless surface oxidation you see on non-anodized aluminum fittings. But if any part of the tank is kept in constant contact with water—such as if it's foamed in place or if water is trapped under a mounting strap, it will eventually lead to corrosion.
There are also definite advantages (and tradeoffs) to using plastic and fiberglass for below deck fuel tanks on larger boats. Corrosion problems due to improper mounting of aluminum tanks have become such a big problem that many builders are moving towards fire retardant plastic tanks and the larger ones are baffled just like the custom aluminum tanks are.
If you are considering replacing your tank with aluminum please read David Pascoe's article on "How to Install an Aluminum Tank so that you Don't Have to Do It Again." It's an excellent article on how to properly mount an aluminum tank to avoid these corrosion problems.
Date: December 23, 2015
From: Jack Reed
When I bought my Endeavour 42 (built in 1985) in October 2006, the fuel tank directly below the engine had sprun a leak and a fiberglass tank had been placed under the starboard setee. This tank is 56 gallons. In the 9 years I have had the boat, I have had no problems with condensation and the tank appears to be very satisfactory. Immediately, I noticed a strange taste to the water and discovered that the tank that had been placed in a vertical position directly in front of the aluminum fuel tank was leaking.
I had the tank pulled, leaving a well in which I have placed by bilge pump. My sole water tank is the one directly below the dining table in the middle of the boat between the setees. I assume that it is reaching the point where it will have to be replaced also, and thus I am interested in how other E42 owners have done this.
Date: December 23, 2015
From: Phillip Mullins
Replaced fuel and water tank in keel in 2012 after running aground. TowBoat US pulled me through a shoal with rocks in the bottom in North Myrtle Beach, SC . This occurrence cut holes in the bottom of the keel and tanks.
New tanks were custom made on site using sheet aluminum. Existing tanks were cut out of foam bedding and hoisted out of main saloon. New tanks were foamed back into place. We had to have a new Teak and Holly floor put in the main saloon afterwards due to the damage getting the old tanks out.
Date: December 24, 2015
From: Eric Grimm
Had my water tank leak. I took the old tank out, took it to a good welder, and had him weld a new alum plate on and then put that old tank right back in. Coast me around $60.00 to fix I think it will be good for another 30 years.
Date: December 25, 2015
From: Wolfgang Harms
In 1998 my original aluminum fuel tank had corroded at the bottom due to bilge water contact (also the water tank). So I replaced both with bladder tanks, custom-made in Holland, ordered through Vetus Marine. These tanks are used on airplanes, coast guard and navy vessels.
Advantages:
Definitely no corrosion, fitted easily. Easily removed, inspected, and cleaned. I had the well carpet lined. 500 liter capacity for each tank.
Disadvantages:
No gauge. I measure by the height between ceiling and tank with an attached measuring tape, which works only to 18” down, 1/3 of the tank volume. No baffling walls. The fittings are flange mounted that need inspection and leaks have occurred but were fixed easily by tightening the flange.
These tanks have lasted well without problems for 17 years, But now I detected a leak near a corner that appears to be a tiny almost invisible 1/8” cut about 5” above a corner fastening strap at the top. No idea how it could have been caused. No sharp objects anywhere. The most likely cause is that I filled the tank to above the maximum, and on a recent ocean voyage with a full tank and a lot of splashing there could have been some extreme stress in the area. The manufacturer recommended to use cargo straps over the tanks which I did not use. But since the cargo straps are not tightened when the fuel goes down and the bladders are attached with extension straps at the upper corners, the cargo straps would not have prevented stress from the corners.
I fixed it the Alcryn material with Hypalon adhesive and a patch from my AB inflatable. The navy sends theirs to repair facilities. In the near future I will not over fill the tank. But I am studying aluminum tanks. Problem is a complete original tank won’t fit through the companion way. It is also hard to inspect and clean, compared to the bladder. I would have to make two tanks. For peace of mind I could make a secondary bladder surrounding the primary bladder, open at the top, as a safety containment. Vetus does not supply them anymore, but there are several US manufacturers.
Date: December 26, 2015
From: Bernie Katchor
Endeavour 43
Cut top off leaking tank leaving 3-inch of it left with cutting wheel cleaned it and ground off corrosion. Using epoxy resin and glass fibreput a 1/4 inch bottom inside tank and 1/8 inch walls wet on wet baffles stayed in place o. Bought enough 3-inch. Aluminium x ,1/4 inch. Drilled holes on each side 2 inch apart placed over Cut area drilled and 1/4 tap for each hole on both tank and lid
Screwed lid down on 5200. The. Glassed Over patched area. Perfect repair. Saw people cutting holes in endeavours hulls and ripping boat apart to do this inexpensive job.
Date: December 27, 2015
From: Joe Blanchard
When I replaced my original tanks, I went back to the original supplier of the tanks and had them build the new tanks. The water tanks had to be modified to get them through the hatch. The redesign of the water tanks allows for a water maker to be installed just fwd of the fwd tank (with additional fittings on the tank for the water maker). Until the water maker is installed, it just gives you some excess storage space. The aft water tank has shorter wings. The tank company has all the blue prints for all my new tanks.
I also replaced the fuel tank and had an additional pickup installed so that I could polish the fuel from that pickup. The new tanks were made out of the same material as the originals (they last about 30 years, long enough for me). When I had the tanks out, I re-enforced the inside walls of the keel with chop fiberglass and installed lead under the tanks (embedded in fiberglass) to correct for the weight loss of smaller tanks) and built a sump under the tanks with a 2-inch pvc access to allow for removing any water that could accumulate under the tanks. The new tanks do not sit in water since a small bilge pump can be lowered into the sump access once the cap is unscrewed.
I used two part foam to secure the new tanks in place and covered the tops of the tanks all the way out to the hull with 5200 to seal the upper bilge. The 5200 flexes with the hull and keeps a waterproof cap on the tanks. Replacing the water tanks are no problem but if you are going to do it, you should go ahead and replace the fuel tank at the same time.
Date: December 28, 2015
From: Don and Gail Buck
Endeavour 37
We replaced our 35 yr old aluminum tanks this past summer (2015) with new aluminum tanks of the exact same size. We put the new tanks exactly where the old tanks came out. We had the boat yard epoxy coat all sides of the new tanks except the tops prior to installation. This was the most efficient way to maintain current fuel and water capacity. Installation was straight forward and the old ones came out and the new ones went in thru the companionway without a problem.
Our cabin sole has 4 panels that lift out exposing the tanks and bilge. Tanks came out without alteration and new tanks were made to exact specs of old tanks so they went in without a problem. This was all done by a subcontractor at the boatyard in St Pete, FL. We did not tackle this ourselves.
Date: January 9, 2016
From: Ed Mahoney
There are many article published on how a Tank installation should be done, many of these suggestions just do not work in a replacement. Even more are challenging given the design of a sailboat. Chocking a tank with Neoprene, at 2 or 3 inch intervals is a great recommendation, but doing that in the curved keel of a sailboat is a big challenge.
Reading all of the notes, and many article before I installed my replacement tanks in 2014, I did just that. However, I found that Neoprene does not compress well, and that the material I used gapped in some areas leaving room for expansion in the tank. As it was filled it ballooned in some cases closing the gaps, in others it simply expanded. No problem until the tank was over pressured, and you can read my story in the newsletter.
For the past few months, since it is winter here in Cleveland, I have been discussing with boat builders, tank manufacturers, resin and foam suppliers and inspected a few dozen boats at the Annapolis and St. Pete boat show. What I found is that things are a lot different today than they were 30 years ago when my E-42 was built, today, I would expect to see Fiberglass tanks as an integral part of the keel. One of the reasons given for this other than corrosion is that the tank itself is much stronger, it cannot expand.
My consensus from all those discussions is that there are several ideal ways, but none is perfect, and all have tradeoffs, so here is my plan when I reinstall.
- Sand the tanks and apply 4 coats of Interprotect 2000E, to all but the top, I put on 2 coats when I put the tanks in in 2014, and those coats are immaculate, I will add 2, and do a touch up on the areas I have to remove the neoprene from.
- Install the tanks with a 2 inch gap between them.
- Glass in a 12” deep area between the tanks that will be the new bilge sump, drill a couple of holes so that air and foam can escape. They will be filled later.
- Foam the tanks with FGCI 8 pound foam, poured through a hose and funnel at temp between 60F and 70F, to allow it time to flow and fill all gaps. I have tested this, at those temperatures this mix flows almost like water, and has a fairly long flow time ~ 4 min. I will probably mix it a quart at a time, and the total used will be about 2 gallons. This foam is also non-corrosive.
- Sand the foam until it is 1” below the tank top.
- Cover the exposed foam with a .25” layer of non-corrosive resin poured warm, so it will flow and close any gaps. It was suggested that I put the resin in warm water before I mix, and pour quickly.
- Scuff the exposed Interprotect.
- Add a layer of Glass as a final sealer and assuring a positive seal on both tank sides and keel sides. I will be able to work all around the tank, since in order to find the leak, I drilled a few 3” holes in the keel which will have to be repaired at the end of the process.
- The top of the tank will be open, the reason for sealing on the sides is that the resin will adhere well to the interprotect, which is well adhered to the aluminum. Resin does not bond well to the aluminum, as those of us with wet tanks have found out.
I hope that this will last at least another 30 years, and I will never have to do it again.
Wish me luck
