Choosing The Right Fuel For Your Boat's Performance

Choosing the right gas for your boat is essential to ensure reliable and optimal performance on the water. The type of gas you should use depends on the type of boat you have, as well as the make and model of your engine. For example, small boats and pontoons usually run on gasoline and ethanol, while larger boats may require diesel. It's important to refer to your owner's manual for guidance on fuel and oil requirements, as using the wrong type of gas can cause significant damage to your engine and fuel system.

Ethanol-free gasoline

Ethanol-free fuel does not cause the corrosive effects associated with ethanol-containing gasoline. It will provide the best performance and lifespan for your boat's engine. However, it is more expensive than E10 or other ethanol-containing gasolines.

Oil and gas mixtures

The type of oil and gas mixture you should use for your boat depends on the type of engine. For instance, smaller outboards and 2-stroke lower-horsepower models require a mixture of oil and gas to help lubricate the engine's internal moving parts. However, most larger, modern boat engines have their own separate lubrication systems, eliminating the need for oil-gas mixtures.

If your boat does require an oil-gas mixture, it is important to refer to the owner's manual for the exact specifications and mixing ratios. Common mixing ratios (gas:oil) include 25:1 (typically during the break-in period), 50:1, and 100:1. To achieve these ratios, you will need to perform some basic calculations. For example, a 50:1 ratio would require 2.6 fluid ounces of oil per gallon of gas.

It is essential to find the correct ratio of oil to gas to prevent issues such as smoking motors, hiccuping performance at high RPMs, and even significant internal damage. Using oil that meets the TC-W standard is recommended to get the best performance and longest life out of 2-stroke engines.

Additionally, it is important to note that the process of mixing oil and gas may vary depending on the setup of your boat. For instance, if your boat has a built-in tank, you may need to estimate the amount of fuel going in before adding the oil. On the other hand, if you have a removable tank, you can simply shake the tank to mix the oil and gas.

Marine gas oil

MGO is used in smaller medium- to high-speed auxiliary units or auxiliary motors and ship engines, which are typically found on fishing boats, small ferries, or tugs. It has a low viscosity, which means it can easily be pumped into the engine at temperatures of around 20°C.

The maximum permissible sulfur content of MGO lies below that of HFO, with a maximum of 1.5% for the ISO 8217 DMA quality label, and less than 0.1% for low-sulfur MGO (LS-MGO). Due to its lower sulfur content, LS-MGO can be used in EU ports or Emission Control Areas (ECAs).

MGO is more expensive than heavy fuel oil, which is why heavy fuel oil is still predominantly used in commercial shipping. However, due to falling prices of heavy fuel oil and the expectation that engine technology will adapt, the use of MGO is predicted to increase in the coming years.

Marine diesel oil

MDO is widely used due to its lower price compared to more refined fuel, and it is particularly favoured by the shipping industry. However, it has been criticised for its high sulfur content, leading to regulations and laws on its use.

MDO is created through a catalytic cracking and visbreaking refinery process. This involves breaking large molecules into small molecules at high temperatures with an appropriate catalyst. The visbreaking process turns the bottom product of the vacuum unit, which has extremely high viscosity, into a lower viscosity, marketable product.

The market for MDO is relatively small compared to on-highway diesel, as it is primarily used in large marine engines that can handle high amounts of petroleum resid.

When choosing an oil for your boat, it is essential to refer to the owner's manual for guidance on fuel and oil requirements. Using the correct marine fuel and oil will ensure reliable performance and compliance with the manufacturer's warranty requirements.

E10 gasoline

E10 fuel is a blend of petrol and ethanol, with ethanol comprising up to 10% of the mixture. This renewable fuel is designed to reduce carbon emissions and our reliance on foreign oil. It is widely available and suitable for most boat engines.

E10 is safe for all outboard marine engines and is approved by major outboard motor manufacturers. It is also covered by the new outboard limited warranty. However, it is important to note that E10 should not be used in engines with more than 10% ethanol, as this will void the warranty.

E10 is known to have some drawbacks. The ethanol in the fuel can attract water into the fuel system, which can cause internal corrosion and uneven performance. This is due to a process called "phase separation", where water accumulates at the bottom of the fuel tank or throughout the fuel system, reducing engine performance and causing corrosion. E10 can also corrode rubber and fibreglass, and degrade fuel lines and other components, leading to clogged fuel lines.

To mitigate these issues, it is recommended to drain E10 from the tank during storage or after 90 days of usage. Using a high-quality fuel additive can also help protect the engine from the potentially damaging effects of ethanol.

The life expectancy of E10 fuel within a boat fuel tank is approximately two months. To improve the longevity of the fuel, it is advised to use a fuel stabiliser or additive every three months.

Frequently asked questions