Friday, November 2, 2012


Although the most cost-effective method to propel a vessel is either by sail or oars, every boat should have an engine, and ideally two: a diesel inboard and a small gasoline outboard that can be used for the dinghy. More than a thousand ships have sunk in the Florida Straits and most of them might have made it to a safe harbor if they’d been able to use mechanical or auxiliary propulsion. In this installment I discuss outboards and inboards, gas and diesel, and two-cycle vs. four-cycle engines. Let’s start with outboards. 

I’ve never owned a boat with big twin outboards; in fact, the largest outboard I’ve ever had was a forty horsepower Yamaha on my Novurania RIB launch…it went plenty fast for me! When I was a kid, the small outboards we used to power our wooden skiffs were typically ten horsepower or less and were manufactured by American companies like Evinrude, Johnson and Mercury. The Japanese have now nearly dominated the outboard motor industry with brands like Honda, Yamaha, Suzuki, Nissan and Tohatsu. Chinese-made outboard engines have begun flooding the market, but I’ve had no experience with them. In addition, there are several American and German manufacturers now producing electric outboards…I know very little about their products, so I won’t discuss them here. And of course, there was the venerable British-made Sea Gull outboard.

            American: Mercury, Evinrude, Johnson
            Japanese:  Honda is best with Yamaha a close second
            in sales, reliability, and customer satisfaction
            British: Seagull for simplicity and durability

Seagull Outboard: “The Best Outboard for the World”
I still like the old British Seagull design for its simplicity. If it breaks, it can usually be fixed it with a screwdriver, a pair of pliers and a pipe-cleaner. During the 1960s, I used a small Sea Gull as an auxiliary, get-home engine on my 21' cruising sailboat. These very basic, lightweight outboards were in production from 1931 through 1999, and have undergone very few changes in design over the past 68 years. They were the outboard of choice of the British Admiralty for their 24-hour continuous-running durability. The incredible torque produced by their 13" diameter prop earned them the nickname "barge pushers"; their 10 hp, 2-cylinder design is rated to push a 30' boat! Parts are still available.

Two-Cycle vs. Four-Cycle engines:
A two-cycle engine is an internal combustion engine that completes a power cycle in just two strokes. The combustion stroke and the beginning of the compression stroke happen simultaneously and perform the intake and exhaust functions at the same time. A four-cycle engine requires four strokes to accomplish the power cycle. Two-cycle engines are used for lightweight applications like garden tools, chainsaws, and two-wheel transportation vehicles. Four-cycle engines are used in most automobile engines and diesel engines. There are exceptions of course, like the two-stroke SAAB automobile engine or the Detroit Diesel engines. 

Outboards: Two-cycle vs. Four-cycle
Four-cycle engines:
            -Less air pollution
            -Don’t need oil mixed into gas
            -Heavier and more durable
            -Much more expensive

Two-cycle engines:
            -Lighter weight for the same horsepower
            -Oil must be mixed with gas
            -Fewer moving parts
            -Less expensive

My Recommendations:
Every bugout boat needs a dinghy, and that dinghy should have a small outboard, 3 hp to 5 hp, to make trips ashore fast and convenient in most weather conditions. For the cost and weight difference, I’m still most comfortable with a two-stroke engine. Buy a used engine…most small, used outboards typically have very few engine hours on them, and need only a carburetor rebuild to have them running like new. Always use fresh gas and make sure you add only the manufacturer’s recommended amount of oil. Add a shot of fuel stabilizer if the engine is going to sit more than a couple of weeks.

Inboards: Diesel or Gas?
Although gasoline inboards are less expensive than diesel engines, they are an ever-present danger to the live-aboard. Unlike gasoline, diesel doesn’t explode! Diesel, leaked into the bilge, will emit fumes that are noxious to some people, but won’t explode like gasoline if the bilge isn’t fan-vented before ignition. Diesel engines are durable and will run for thousands of hours. An older diesel that has become inoperable usually needs only minor repairs to make it run again. As they say in North Florida, “It’s broke, but it ain’t busted.” In most cases, a diesel engine will last longer than your lifetime.

If a diesel engine fails to start the problem is usually: fuel, fuel, or fuel! There’s no electrical system needed for combustion; compression alone ignites the fuel. Make sure you have an in-line Racor-type filter to remove the water that invariably finds its way into fuel tanks. Fuel filters will remove trash that might clog injectors. Clean fuel burns clean, but a smoky diesel might very well run for years. If you’re relying on your bugout boat as a survival platform, in my opinion, diesel is the best option. 

Diesel Engines to Avoid:
Perkins: Parts are difficult to find
Volvo: Parts are very expensive
Detroit: High horsepower/high revolution engines
mean high fuel consumption & short time between rebuilds

Recommended Diesel Engines:
Caterpillar: I like the 3208 naturals (non-turbo) 
Cummins: Reliable, American-made
Lehman: Made by Ford; easy to work on
John Deere: A very dependable tractor engine
Kubota: Japanese tractor engine, also used in older Onan generators
Yanmar: Lightweight, popular as a replacement engine option

Some Unusual Diesel Engines: Lister, Gardner, Buda.
Lister: (Listeroid) This unique diesel engine has the ability to burn any type of oil including petroleum diesel, bio-diesel, or vegetable oil. Like Rudolph Diesel’s original engine, which was run on peanut oil, Lister engines can even run on used cooking oil! The Lister was the first “cold start” diesel engine, which could start up from compression alone, without the aid of a glowplug, hot bulb, or other heating system…no ignition system was needed. No longer made in England, “Listeroid” diesels are now made in China and India. Lack of quality control may be a problem.

Gardner: This reliable British-built diesel was manufactured for nearly one hundred years until production ceased in the late 1990s. Primarily used for commercial applications, it has the unique ability to operate with several of its cylinders manually closed down for fuel efficiency. It can also be started using an external compressed air tank or by hand-cranking. This diesel is often found in North Sea trawlers, (which make very nice live-aboard conversions.) These slow-turning diesels last for generations.

Buda:  Started in Illinois in 1881, the Buda Engine Company was later acquired by Allis-Chalmers and these engines are still used to power heavy construction equipment. The company also produced two- and four-cylinder models that were popular in Navy and Coast Guard lifeboats for their rugged dependability. They can be hand-cranked. Easily converted to live-aboards, lifeboats are another very affordable source of seaworthy bugout boats; if you find one with a Buda engine in it, you’re in luck!

In my next installment I’ll discuss water-makers, including a very affordable unit that you can build using the high-pressure pump from an off-the-shelf pressure washer.



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  7. I think you made a good point about how inboard diesel engines have certain advantages over gasoline engines. It sounds like gasoline engines are better for people who only takes the boat out a few times a year for short rides. For someone planning to spend a lot of time on their boat, who maybe lives closer to the water, a more durable motor would be ideal.

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