Why use outboards?

Dear All,

Cost Savings for Boat Operators


Fuel Savings up to 52 % can be archived by using Levi Surface Drives with Diesel engines .

On 30.1.2007 a fuel consumption test using two identical, fiberglass Malay fishing boats was carried out. Similar boats are used by tour operators and transport companies.

Test conditions

The “Defender” was a brand new fiberglass 25 foot long, 7 foot wide Malay fishing boat equipped with a new 60 hp Yamaha 2 stroke petrol engine.

The ‘Challenger” was a 25 foot, 7 foot wide, 2 year old Malay Fishing boat equipped with a Levi Drive 170-150 coupled to a Koysan Gearbox and a marinised Isuzu 4JB1 second hand truck engine.

Both boats were produced from the same mold and by the same builder.

Each boat had two crew members.

The estimated total weight of the “Defender” was about 1200 kg. The estimated weight for the “Challenger” was in the ranged of 1500 kg.

The difference in weight is due to the heavier diesel engine, gearbox and Levi Surface Drive.

The test was done over a distance of 10 nautical miles (Penang Seagate, to Jelutong return to Seagate). The wind and sea conditions during the test were calm.

The two boats were traveling at the same speed (about 27 knots) side by side.

Test result

The fuel consumed of the “Defender” was 20.2 liters of outboard engine petrol fuel
(petrol plus 2% two stroke oil).

The fuel consumed by the “Challenger” was 9.7 liters of diesel.

The fuel savings using “Levi Surface Propulsion” and “Inboard Diesel Engines” amounts to 52 % measured in liters. The environmental emission is drastically reduced.

The monetary savings would even be higher since diesel oil is in most countries cheaper than petrol and diesel engines don’t require two stroke oil.


Best Regards

Rudolf Scholz

Naval Architect

 

The 'defender' could carry more cargo? (more space - no engine in the way!) earns more which offsets cost of fuel! When engine breaks down 'challenger' is stuck in dock - earns nothing! 'defender' takes off outboard and lands it to machine shop! puts on hired engine and does another trip which pays for hired engine and makes a profit because there's only one boat running that day!

NO, why do we use an outboard rather than an inboard?

 

Surface Drive versus Outbaord engine

In theory you could be right.

In praxis it look a bit like this. Outboard engines last in this waters about 3 years. After the second year the costs for repairs are kicking in.
Diesel engines (even second hand marinised diesel engines) last much longer. Our fisher use second hand diesels 10-12 years without much problems. These engines are very badly treated and but work every day.

To change a diesel engine in an open boat takes about 3 hours with the help of a chain block.
The time to change an outboard engine (60 hp) should be about half the time These heavier outboard engines (60 hp about 100 kg) require a chainblock also. They are normally bolted to the transome to avoid theft.

Mechanics come to the boat to for small outboard motor repairs. Larger repairs are carried out in the workshop. These mechannics need to be specially trained to service an outbaord engine since this engines are highly sophisticated.
Diesel mechanics are easly found at most motor workshops. Spare parts are easy available at low costs. It is not worthto do larger repairs on this engines.
Mr. Choong paid about 1800 $ US for his second hand engine. He did not do anything to the engine except changing the oil before installation.

To drive the boat in to the box at low tide, he uses the engine. The mud flyes around during this operation.
He has hit a sand bank with his boat while travelling at 27 knots. When the tide came in, he used the propeller to push the boat off.
The system is not designed for such a treatment but takes it. He has changed the propeller once after hitting a log in the river.

Best Regards

Rudi



The outboard owner is so broke from the high fuel bill and extended repair cost that he can't afford to hire an exchange engine.

 

xrudi you are of course absolutely right what we do in practice may not always be the right answer to the problem! And what is put down as theory can be total rubbish! But as you forgot to state the real reason for using a diesel (the fact that you can knock it about and it lasts for ever) my question stands! Personnally in your situation and location I'd probably go for the inboard diesel every time, but there are cases when the outboard could be the better option (not many and mostly illegal)!

 

4 Stroke or Evinrude ETEC?

Of course the cost factor would be different if you compared the diesel to a modern 4 stroke or Evinrude's ETEC (I think that is what it is called. 2 Stroke with 4 stroke fuel economy and quiet running)

I fish on a mates 5m regularly and he just updated to the ETEC, fantastic engine, very quiet and fuel efficient but still gets on the plane very quickly. (The replaced motor was a 5 year old evinrude, same HP)

I think inboard engines are often overlooked by people, obviously in smaller boats you loose a lot of room to them in comparison to an outboard but once you get larger (23ft ish?) I would prefer the inboard

 

If you want to pull anything like a net or even another boat, surface drives are abaslutely usless at this.

I think you will find that not one surface drive manufacturer that knows what he is doing will argue with that.

Some twin engine installations can plane with one engine. I have never heard of a surface drive that can do this.

 

the other benefits of diesel engines

There is no question that diesel engines are more efficient than 2 stroke or 4 stroke petrol engines. Diesel engines and our Levi surface drives are a good combination.
VW in Germany has developed a diesel car which can run 100 km on one liter diesel. wait for the thing to come
We boaters have to do something for the environment before we can get the new light weight, fuel efficient diesel engines for our boats. With a diesel engine this is easy. Use your old cocking oil and make bio-diesel. The web is full of instruction (Journey Forever). It might even be cheaper than your diesel at the pump. For people in third world countries this might be a way to survive.