Gasoline Diesel or Sail.

While sail is a source of powering a boat a sail boat is often complemented with an auxiliary engine. That engine can be either and inboard or outboard gasoline engine, or an inboard diesel engine. But in either case the main power for a sail boat is wind. Trawlers often have a sail that uses wind as an auxiliary power source with a diesel engine as a main power source but not always.

Gasoline or Diesel Engines

Gasoline is an explosive fuel. Gasoline fuel systems, engines, and machinery that is located in engine compartments must follow certain rules. These rules are set forth in what is referred to as standards, recommendations, and laws. These Standards, Recommendations and Laws are the result of years of research by many organizations.

 The United States Coast Guard will adopt some of these standards and recommendations and make them law. The law is what is referred to as the Code of Federal Regulations. Title 33 and Title 46 of the United States Code this code empowers the USCG. 

While many organizations contribute to establishment of standards or recommendations the two mostly quoted by Marine Surveyors when discussing gasoline engines are the American Boat and Yacht Council and the National Fire Protection Association. Gasoline engines in boats need special fire protection systems. These include J1527 explosion proof equipment in the engine compartments. Special fuel lines, grounding requirements for fuel systems, gasoline tank requirements are all safety precautions needed when dealing with gasoline engines. 

Gasoline has a flash point of -45 below zero what that means is that gasoline will give off enough vapors to ignite at -45 below zero it’s flash point. If sufficient vapors are given at such low temperature image how much more vapors are given at 90 degrees and how easier an explosion can occur. Gasoline vapors are heavier than air so when any vapors escape they will naturally sink to the lower lever. If gasoline vapors escape from a car engine they will sink to the pavement. If gasoline vapors escape from a boat engine they will accumulate in the bilge of the boat. This is why so many standards, recommendations and regulations apply to gasoline engines.

Diesel fuel has a flash point of 125 degrees. That means that it will not produce enough vapors to ignite until it reaches 125 degrees. The higher ignition temperature makes it a safer fuel.

Gasoline engines burn more gallons of fuel per hour that diesel engines of the same horse power. This makes diesel engine more economical to operate.

Diesel engines have more torque meaning they can turn larger propellers thus push more water.

A gasoline engine is less expensive to manufacture than a diesel engine. So the engine will cost less and since diesel engines cost more, boats with diesels are valued higher. Gasoline engines ignite fuel by using a spark plug while diesel engines compress the fuel for ignition. A gasoline engine weighs less than a diesel and will deliver more horse power in relation to weight and size.

The greater majority of power boats less than 36 feet will have gasoline engines. Once boats exceed 36 feet diesel engines become more common. Cost, needed horse power and size are the driving factors which determine if a boat is equipped with a gasoline or diesel engine..

I have often been told by first time boat buyers that they want a diesel engine for safety reasons. Well there is nothing wrong with that but it is not always practical in every case. Especially when considering that your first boat may be less than 36 feet. While gasoline may have its draw backs, when handled properly it is safe. The economical savings of using diesel fuel may not offset the initial cost of the engine. This will depend on how often you use your boat.