Amanda Knapp
Replacing the gas tank in a fibreglass boat is a complex task that often requires professional assistance. The process involves disassembling the boat to remove the old tank, installing a new tank, and repairing the boat's structure. The cost of replacement includes not just the new tank but also labour-intensive installation. Before installing a new tank, it is important to check for water leaks and damage caused by ethanol-blend gasoline, which can cause corrosion and ruin the tank. Today, fibreglass tanks that are ethanol-compatible are available, but alternatives such as plastic and rotationally moulded polyurethane tanks are also viable options that are tough, corrosion-resistant, and unaffected by gasoline or diesel.
Characteristics and Values Table for Replacing a Gas Tank in a Fiberglass Boat
| Characteristics | Values |
|---|---|
| Reasons for Replacement | Leaks, cracks, corrosion, installation issues, ethanol damage, or general deterioration |
| Replacement Options | Polyethylene, rotationally-molded polyurethane, aluminum, stainless steel, or fiberglass (ethanol-compatible) |
| Replacement Process | Disassemble/open the boat, remove the old tank, install the new tank, plumbing and wiring, repair/reassemble the deck and structure, perform a leak test |
| Considerations | Accessibility varies by boat, some decks may need to be cut and reglassed, internal flotation foam may need to be removed, replacement is labor-intensive and costly |
| Regulations | USCG/EPA regulations for construction, thickness, grounding, venting, pressure checks, load distribution, and insulation |
| Manufacturer Recommendations | Prep mounting surface, securely strap the tank, avoid re-foaming, follow specific instructions to avoid voiding the warranty |
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What You'll Learn
Ethanol-induced corrosion
Although it is strong, lightweight, and resistant to corrosion, fiberglass is not the best material for a boat fuel tank. Ethanol-induced corrosion is a common problem in fiberglass tanks, and it can lead to costly repairs.
Ethanol is a solvent, and when added to gasoline, it can wash uncatalyzed components in fiberglass resin out of a fuel tank's laminate and carry them into the engine. This leaves boat owners with expensive repair bills. The solvent properties of ethanol break down the resin in the fiberglass, and the ethanol-laced gasoline can even dissolve the tank, sending bits of resin to clog filters and ultimately eating a hole through the tank. This is a problem that has been observed in California and New York, the first states to adopt ethanol-blended gasoline.
The addition of ethanol to gasoline can also cause corrosion in several other ways. Firstly, ethanol has a propensity to absorb water, which leads to water accumulation in the fuel tank. This can cause corrosion in itself, but the electrical conductivity of the water could also result in galvanic corrosion. Secondly, microbes love to feed on biofuels like ethanol, and the presence of ethanol in water samples from tanks has been linked to microbial activity and corrosion.
To avoid these issues, some boat owners are choosing to replace their fiberglass tanks with plastic (polyethylene) or aluminum tanks, which are more resistant to corrosion and the effects of ethanol-blended gasoline. However, replacing a fuel tank is not an easy task and often requires the expertise of a professional. It can involve cutting through the deck and hull to remove the old tank and then re-fiberglassing major sections back together to install the new one.
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Removing the old tank
Firstly, it is crucial to ensure that the boat is safe to work on. If the tank has leaked, it is important to check for any residual fuel or fumes that could pose a hazard. In some cases, the internal flotation foam in the hull may be soaked with leaked fuel, which will need to be carefully removed using hand tools to avoid sparks. It is also important to ensure proper ventilation and take necessary precautions, such as wearing protective gear, when working with hazardous materials.
Next, access to the fuel tank needs to be gained. This can vary depending on the boat's design. Some boats may have easily accessible compartments, while others may require cutting or sawing through the deck to reach the tank. If the tank is located under a solid deck, it may be necessary to remove screws or other fasteners to lift or remove the deck carefully. It is important to be cautious when cutting or drilling to avoid damaging other critical components or structures.
Once access to the tank is gained, the next step is to disconnect and detach all the connected components carefully. This includes hoses, clamps, filters, wiring, and any other attachments. It is important to label or mark these connections to ensure proper installation of the new tank. After detaching the connections, the old tank can be carefully lifted or slid out, depending on the space available. This process may require multiple people, as fuel tanks can be heavy and awkward to handle.
In some cases, the tank may have been "foamed in place," which means it was installed with expanding foam to fill the space and secure the tank. If the tank has leaked, the foam will need to be carefully removed, as it will be saturated with fuel and pose a hazard. The foam removal process can be tedious and time-consuming, ensuring that all residual fuel is eliminated.
Finally, after successfully removing the old tank, it is essential to inspect the surrounding area for any damage or corrosion caused by the leaking tank. Any necessary repairs or replacements should be made before installing the new tank to ensure a safe and proper installation. This may include cleaning, drying, and treating any affected areas to prevent further issues.
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Installing the new tank
Installing a new fuel tank in a fibreglass boat is a complex and labour-intensive process, and in most cases, it is a job best left to professionals. The process will vary depending on the boat, but there are several key steps that are typically involved.
Firstly, access to the tank must be gained. This may involve simply removing screws and deck components, or it may require cutting a large hole in the deck. If the tank was foamed in place, the foam will also need to be removed, as it is likely to be saturated with fuel. Once the old tank is accessible, it can be disconnected and removed.
The new tank can then be installed, following the manufacturer's instructions and USCG regulations. This includes prepping the mounting surface, securely strapping the tank down, and attaching the plumbing and vent lines. Hose clamps are used to secure the lines, and the sender and grounding wires are then connected.
After the tank is in place, it must be leak-tested to ensure there are no cracks or leaks. This is a critical step to ensure the safety of the boat and its occupants. Finally, the boat's structure can be repaired or reassembled, including reglassing the deck if necessary.
It is important to note that the use of ethanol-blend gasoline can cause corrosion in aluminium tanks and break down the resin in fibreglass tanks, leading to water accumulation and potential galvanic corrosion. As such, it is recommended to use a fuel treatment regularly to keep water out of the tank and to opt for a tank made from a different material, such as polyethylene or rotationally moulded polyurethane.
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$68.39 $71.99
Repairing the deck
Assessing the Damage and Planning the Repair
Before starting the repair, it's important to thoroughly inspect the deck and identify the extent of the damage. Look for any signs of deterioration, such as cracks, soft spots, or delamination. Take measurements and note the location of any damaged areas. This will help in planning the repair and determining the materials and tools needed.
Removing the Damaged Deck Area
Based on the assessment, use appropriate tools to carefully remove the damaged sections of the deck. This may involve cutting, grinding, or peeling away the affected fibreglass layers. It is crucial to wear the appropriate protective gear, including eye protection, gloves, and a respirator, during this process, as it can create hazardous dust and fibres.
Preparing the Surface
Once the damaged area is removed, prepare the surface for the repair. This includes cleaning and degreasing the area to ensure that the new fibreglass will adhere properly. Use a wire brush or sandpaper to roughen the surface, creating a better bond for the new material. Ensure that the work area is well-ventilated, and follow all safety guidelines when working with fibreglass and resin.
Replacing the Deck with New Fibreglass
Measure and cut new fibreglass cloth or matting to fit the prepared area. Mix the appropriate resin and hardener, following the manufacturer's instructions, and apply it to the cloth or matting. Carefully lay the fibreglass into place, smoothing out any air bubbles or wrinkles. Ensure proper alignment and a seamless fit with the existing deck.
Curing and Finishing
Allow the fibreglass resin to cure completely according to the manufacturer's recommended time and conditions. Once cured, sand the repaired area to create a smooth finish, blending it with the surrounding deck. If necessary, apply a gel coat or other suitable coating to match the colour and texture of the original deck, enhancing the appearance and providing additional protection.
Structural Reinforcement
Depending on the size and location of the repair, consider adding structural reinforcement to the deck. This could involve using additional layers of fibreglass or incorporating core materials, such as wood or foam, to enhance the strength and rigidity of the repaired area. Consult with a professional or refer to boatbuilding resources for guidance on structural reinforcement techniques.
Remember, repairing the deck of a fibreglass boat is a significant undertaking, and it's essential to have the necessary skills, tools, and safety equipment. If you are unsure or uncomfortable with any aspect of the repair, it is always best to consult a professional boat repair specialist to ensure a safe and durable outcome.
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Alternative tank materials
When it comes to alternative tank materials for a fibreglass boat, there are several options available.
One option is to opt for an aluminium tank. Aluminium is a popular choice for boat fuel tanks and is widely used by boat manufacturers. However, it is important to note that aluminium tanks may be susceptible to corrosion, especially when used with ethanol-blend gasoline. This is because ethanol has a tendency to absorb water, which can lead to a build-up of water in the fuel tank, potentially causing corrosion. Nevertheless, with proper care and maintenance, aluminium tanks can be a durable and reliable option.
Another alternative is stainless steel. While stainless steel tanks are known for their durability and longevity, they may not be the best choice for fuel tanks due to condensation concerns. Stainless steel tanks can be costly and may require proper welding to ensure their integrity. Additionally, in some regions, such as the USA, there may be regulations prohibiting the use of stainless steel fuel tanks in boats. Therefore, it is important to consult local regulations before opting for a stainless steel tank.
Plastic, specifically polyethylene, is another alternative tank material that has gained popularity. Plastic tanks are known for their toughness, corrosion resistance, and compatibility with both gasoline and diesel. Cross-linked polyethylene (XLPE) and linear polyethylene are commonly used, offering a seamless and inert tank solution. However, one potential drawback is the permeation of fumes through the material, although this may not pose a significant safety risk.
In recent years, rotationally moulded polyurethane tanks have emerged as a viable option for replacing aluminium or fibreglass tanks. These tanks offer several advantages, including corrosion resistance, extreme durability, and cost-effectiveness. Polyurethane tanks are approved for use with both gas and diesel applications and can be customised to fit specific mounting requirements.
Lastly, some boaters may consider alternative fuels as a way to "green" their boating experience. Options like biodiesel, propane, and isobutanol can reduce emissions and provide a more environmentally friendly alternative to conventional diesel or gasoline. However, it is important to research and understand the specific requirements and compatibility of these alternative fuels with your boat's systems before making the switch.
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Frequently asked questions
If your boat has a gas engine and a fiberglass tank, you must replace the tank if you ever run gas with ethanol in it, as ethanol will destroy the fiberglass.
If you don't replace the gas tank, you risk leaks and other issues that could cause a fire or explosion.
You can replace your fiberglass gas tank with a new fiberglass tank that is ethanol-compatible, or you can switch to a different material such as aluminum, polyethylene, or rotationally molded polyurethane.
Replacing a fuel tank in a boat typically involves disassembling and/or opening up the boat to remove the old tank, installing the new tank according to the manufacturer's instructions and USCG regulations, plumbing and wiring the tank, and then repairing or reassembling the deck and structure.
