Flats Boat Fuel Tank Replacement: A Step-By-Step Guide

Replacing the fuel tank on a flats boat is a complex and labour-intensive task. Before starting, it is important to check for any leaks in the boat's hoses, clamps, and filter. If a leak is detected, the tank will need to be removed and replaced. This process can be challenging, as it often requires cutting through the deck or bulkhead to access the tank. It is crucial to take safety precautions when working with exposed fuel and to ensure that all fittings are plugged before starting. Additionally, the internal flotation foam in the hull may need to be removed with hand tools to avoid sparks. The replacement tank should be properly installed and secured to avoid safety hazards and premature tank failure.

Removing a below-deck fuel tank

Step 1: Safety First

Before beginning any work, it is crucial to prioritise safety. Ensure the tank is empty and all fittings are securely plugged. Remember that you will be working with exposed fuel and a tank containing fuel vapours, so take the necessary precautions to avoid any accidents.

Step 2: Assess the Situation

Start by examining the construction of the boat and the fuel tank's placement. Check if the tank is foamed in or if there is any wood framing or construction around it. This information will be useful when planning the removal process.

Step 3: Gather the Necessary Tools

You will need various tools for the job, such as a circular saw, a measuring tape, a screwdriver or drill, and personal protective equipment (PPE) like gloves and eye protection. Make sure you have everything you need before starting the removal process.

Step 4: Plan the Cutting

Use a measuring tape to determine the location of the stringers, bulkheads, and other structural components. Mark the cutting lines on the deck, ensuring that the opening will be large enough to lift the tank out. Cut a small hole at each corner of the tank to help you locate the stringers and bulkheads.

Step 5: Start Cutting

Set the depth of your circular saw to 1/2 inch and begin cutting along the marked lines. Cut down the middle of the stringers and bulkheads, creating a "flange" that you can attach the new deck to later. Be extremely careful during this step to avoid damaging any critical components.

Step 6: Remove the Tank

Once you have created a large enough opening, carefully remove the fuel tank. It may be attached with screws or stuck to the hull with leftover foam. Detach any screws and use an electric chainsaw to cut through the foam if necessary.

Step 7: Clean and Inspect

With the tank removed, clean the area thoroughly to eliminate any residual fuel. Use a strong detergent and water to purge the tank and surrounding areas. Also, inspect the tank for any signs of damage or leaks.

Step 8: Prepare for Reinstallation

If you plan to reinstall a new tank, follow the manufacturer's instructions and ensure compliance with Coast Guard specifications. You may also need to install a new deck, so refer to resources on how to foam a hull and glass a deck for guidance.

Remember to take your time, work methodically, and always put safety first. Removing a below-deck fuel tank can be a complex task, but with careful planning and execution, you can successfully complete the job.

Choosing the right replacement tank

When it comes to choosing a replacement fuel tank for your flats boat, there are several factors to consider. Firstly, determine the appropriate size of the fuel tank based on your boat's fuel consumption and range requirements. Consider how long you typically run the engine, how often you use the boat, and the distance travelled on each trip. If you plan on spending extended periods on the water or travelling long distances without refuelling, a larger tank may be necessary.

Next, consider the material of the tank. The most common materials are aluminium, plastic, and stainless steel. Aluminium is lightweight, durable, and corrosion-resistant, but it can react with ethanol fuel additives if untreated. Plastic is also lightweight and corrosion-resistant, and it's more affordable, but it's not as strong as aluminium and may crack or leak if not maintained properly. Stainless steel is a durable and corrosion-resistant option for larger permanent tanks, but it's more expensive and challenging to work with.

Another key consideration is the type of fuel tank: portable or permanent. Portable tanks are designed for easy removal and refuelling, usually made of plastic, and range from one-gallon to fifty-gallon capacities. Permanent tanks, on the other hand, are installed in the boat's hull and cannot be removed. They are typically made of aluminium or plastic and can hold ten to several hundred gallons of fuel. Permanent tanks are more common on powerboats.

When choosing a replacement tank, it's crucial to ensure it meets safety regulations and is properly vented. Additionally, consider the installation requirements and consult a professional for permanent tank installations. Think about the layout of your boat and the available space when selecting a portable tank.

Finally, don't forget to maintain your fuel tank properly. Regularly inspect and clean the tank, and check the fittings, hoses, and connections for any signs of wear or damage.

Tank installation

Before installing a new tank, it is important to ensure that the compartment is properly prepared. This includes draining any fuel or gas that may have leaked and removing any internal flotation foam that has been soaked with fuel. Power tools should not be used in this process as they may create sparks. Once the compartment is clear, the new tank can be installed following the manufacturer's instructions. It is important to follow these instructions carefully to ensure safety and prolong the life of the tank.

When choosing a replacement tank, there are several options available. Most marine tanks are made from aluminum, but stainless steel, permanent polyurethane, and plastic tanks are also available. Rotationally molded polyurethane tanks are a durable and cost-effective option, while custom aluminum tanks can be built to exact specifications. It is important to consider the size and shape of the tank, as well as any additional features that may be required, such as internal fuel pumps or baffles to minimize sloshing.

After the new tank has been installed, it is important to test it to ensure that there are no leaks. This can be done by filling the tank and checking for any signs of leakage. It is also important to properly ventilate the compartment to prevent the buildup of salt water and moisture, which can lead to corrosion. Regular maintenance and inspections can help prolong the life of the tank and ensure the safety of the boat.

Removing old tanks safely

Firstly, ensure that the tank is completely empty and that all fittings are securely plugged. This is a critical step to reduce the risk of fire or explosion. It is also recommended to purge the tank with a strong detergent and water solution to remove any remaining fuel residue.

Next, identify the location of the fuel tank and assess the accessibility. If the tank is located below the deck, you may need to cut an opening in the deck to access it. Before cutting, measure the size and location of the stringers, bulkheads, and other structural components. This will help you determine where to cut and ensure that you don't damage any critical components.

Once you have identified the location and accessibility of the tank, it's time to start removing it. If the tank is not foamed in, you may be able to simply unscrew and remove it. However, if it is foamed in, you will need to use tools to carefully cut the foam away from the tank. Be cautious when cutting to avoid damaging the tank or any surrounding components.

After the tank is accessible, you will need to disconnect any hoses, clamps, or other connections. Again, be cautious when working around fuel lines to avoid spills or leaks. Once the connections are disconnected, you should be able to lift the tank out of its compartment.

If the tank is aluminium, it can be safely cleaned with an air grinder and the proper wheel, combined with safe workmanship. However, it is generally recommended to replace the tank rather than attempting to repair or weld it. This is because a damaged tank can pose a significant safety risk, and a new tank will provide better reliability and peace of mind.

Finally, dispose of the old tank properly. Do not attempt to reuse or recycle the tank without proper knowledge and equipment. Old fuel tanks can be hazardous, so it is important to follow local regulations and guidelines for their disposal.

Cost of replacement

The cost of replacing a fuel tank on a flats boat can vary depending on several factors, including the size and type of the tank, labour rates, and the difficulty of removing the old tank.

The cost of a new custom fuel tank can range from $10 to $20 per gallon, depending on local business costs. For example, a 120-gallon tank could cost around $1,200. The installation can add a few thousand dollars to the overall cost, depending on labour rates, any necessary structural repairs, fuel line replacements, and the ease of removing the old tank.

In some cases, additional costs may arise if there are hidden issues or if specialised equipment or materials are required. For instance, if the tank needs to be barrier-coated or secured in a specific manner, this could increase the final cost.

It is worth noting that the removal process can vary significantly depending on the boat's design and the fuel tank's location. In some cases, simply cutting out the old tank may be necessary, while other boats may have an accessible design that makes removal easier.

Overall, the total cost of replacing a fuel tank on a flats boat can range from a few thousand to tens of thousands of dollars, depending on the specific circumstances and requirements.

Frequently asked questions