One of the questions I’m often asked when inspecting boats, particularly older ones, is “Can I repair old tanks if I don’t want plastic or stainless steel instead?” Well of course you can, but you just have to get the job done right because the last thing you need is a fake job leaking fuel or water everywhere, filling up your bilges. The top priority, of course, is safety issues and you can be sure that if there is a fire or damage due to leaking tanks, your insurance will almost certainly be deemed null and void. In many cases the tank will be beyond redemption, but the tank may well be used to allow a new tank to be molded from the old one, depending of course on your own GRP skills and the spare time you have to do it. in.
There are several stages in the repair of tanks and certain criteria to take into account before beginning the work in question. Fuel tanks have a different function than water tanks, but repairs to both must be adequate, safe, and robust. Materials must also be considered and a decision made as to whether the repair can be considered financially viable, although in most cases the price of a new tank is quite high.
DAMAGE ASSESSMENT
One of the questions that needs to be answered quite early in the article is ‘Will it be an internal repair or an external repair?’ Naturally, the job may well make a difference if the inspection panels can be lifted immediately to allow access for repair. The other critical question is. ‘Where is it leaking and how bad is the damage?’ This can be extremely tricky and often very tricky. A small leak from a puncture on the rim of a tank can run several feet along the pipes, down slopes, and drip grumpily somewhere quite different, throwing you astray! The problem can be exacerbated by rain or leaking pipes from above, giving the leak an added dimension. Worse still, and even more unfair, a tank can drip from several places at once, but it can come out downhill in a very different place! Beware also, flange leak or faucet dripping undetected along the pipe, below the bottom of the tank, giving the misleading impression that the problem is actually the tank itself. Proper leak identification is critical before going to the big trouble of removing the tank only to find out it wasn’t worth it! Sounds terribly obvious, doesn’t it, but you’d be surprised. Don’t be fooled by tiny little leaks. In steel and aluminum tanks, a puncture is sometimes just indicative of a much bigger problem inside.
Many tank leaks are caused by corrosion, which is the inevitable result of water sitting untouched at the bottom for years. Steel tanks suffer greatly from this, and puncture leakage is often the first sign that the paper-thin bottom is about to fall out, in addition to the contents. Aluminum tanks also have their own problems. Many alloy tanks are worn by people and are often not marine grade aluminum alloy. This means that if they are left to sit in seawater, their chances of surviving ultimate corrosion and failure are close to zero. Wrong grade alloy literally melts in seawater! Extensive damage can be done if aluminum tanks are placed on rubber mats or cushioned with rubber inserts under steel retaining straps. Certain brands of rubber contain chloride and this also destroys aluminum alloys at an alarming rate. Leaving damp rags on top of alloy tanks is also bad news, as the corrosion resulting from the poultice producing a hideous sticky white substance is also highly corrosive. The same goes for nuts and bolts and any tools left on top of tanks, dissimilar metal corrosion is alive and well in these cases, all wreaking their own particular havoc!
Now that I’ve managed to scare them to death, what do we have? The leak has been identified, assessed and the tank will most likely have to be removed in most cases. It’s a little annoying, but overall it’s a good thing because you can check all the hidden areas behind and clean them out at least while the tank is away. A guy I knew did the same and found a heavy bag of oil behind the tank. Opening it up he found a .45 automatic pistol and a couple boxes of bullets…what I want to know is how the heck did the previous owner forget about that. We’ll never know I guess, maybe he never knew? It was probably his wife’s! Once the tank is out, a lot will become clear. The next stage is about to evolve and we can really take on the beast.
THE REPAIR ITSELF
Assuming the tank was initially emptied of its contents, we can now decide, can we repair internally or not? Remove the inspection panels and make a decision whether it is possible to work inside. Being able to see what you are doing is vital. If you have enough space to see and work, great. However, it remains a firm rule that all tanks, large or small, fuel or water, glass or metal, copper or steel, must all be spotlessly clean, free of grease, rust, dust, slime, dust, no particles. , without anything. Am I clear? Cleanliness is next to mercy in these cases, a good repair starts out spotless. Once clean, it should be thoroughly degreased. For steel, copper, brass, and alloys, it helps if it’s also a shiny metal! If the bottom appears to be leaking, two layers of CSM (Chopped Strand Mat) will usually be enough about 1.5 ounces to ensure the glass rises about ¾ inch above the bottom throughout the interior.
If further investigation of the leak at the bottom shows weaker metal and a larger hole (or several) appear, then you’d better make sure the repair is done from the outside. This can be accomplished by backing the moistened fiberglass mat with a rigid, cellophane-covered piece of cardboard, which is, in turn, firmly taped to the bottom of the tank. This ensures that the glass does not bend, droop, or even fall under its own weight during curing. Be generous with the size of the patch, the bigger the better. Curing can be facilitated by heating with a hair dryer or even adding a bit more to the resin/catalyst mix. NO, however if using epoxy resin… only strict measurements please! Allow a minimum of 12-15 hours, preferably overnight. Please note: Gasoline tanks must be steam cleaned prior to any repairs
Remember, in the case of fuel tanks, it is essential that the repair is completely degreased. The resin will almost certainly not adhere and the process will have to be repeated one more time. Degreasing can be done with trichlorethylene, carbon tetrachloride, detergent solution, or a proprietary degreaser. Don’t short this step…you can’t say you weren’t warned!
Sealed tanks, of course, need to be repaired from the outside and it may be worth considering completely covering the entire tank with glass, especially if you use a couple of layers of fine cloth and filled resin to do so. You can give the tank a whole new life, especially if you paint it a bright new color afterwards. However, be careful that corroded parts do not come loose in the future, which could block pipes, filters and cause the engine to stall at a very awkward moment. An additional suggestion in this scenario to ensure there are no loose particles is to pour 2-3 liters of resin/catalyst mix into the fill tube through a funnel to completely seal the bottom and forever preserve any loose flakes or dust after glass. the outside. It’s so cheap to make and so worth the extra effort!
LEAKY SEAMS
A leaky seam may seem like an impossible job, but with patience it’s a piece of cake. Thoroughly clean the entire contour of the seams and degrease. Simply mend around the entire seam overlap on both ends of the tank.
A WORD ABOUT WATER TANKS
When water tanks are repaired with general purpose (polyester) resins, the styrene residue that is present (about 50 parts per million) imparts a “taste” to the water. It’s not harmful as such, but it’s quite undesirable and the flavor will linger for some time. On boats or caravans, the water does not use up as quickly and it can take time to rinse. However, certain resins that are recommended for potable water supplies may be used. Check with your resin supplier for advice. However, always cure water tanks for at least seven days and rinse repeatedly with hot water, which removes much of the styrene taste. You can also steam clean the tank at your local garage for a reasonable fee… well worth it.
TEMPORARY REPAIR
On a boat it is vital to always have something on hand to repair a sudden leak or pipe break. There are several varieties of two-part epoxy putty and epoxy pipe tapes available. Make sure the temporary repair doesn’t end up permanent though, some of these putties actually work well even soaked in fuel or water. sure!
With today’s increasing costs, new tanks are indeed expensive, several thousand for large yachts and it is always satisfying to be able to perform a safe and efficient repair for the fraction of the cost of replacing them. It takes a little extra effort, but think of the hundreds of hours of work it would take to pay hundreds of extra dollars for new ones.
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