Surface Drive versus Outboard Engine

[xrudi]

Hello,

We have developed a small surface drive unit (Levi Drive 170-150) and installed it on a local Malay fishing boat. The speed archived with a 55 hp Isuzu marinised truck engine was over 27 knots.

We did also some fuel consumption tests and compared it with a common 60 hp outboard engine. We had a fuel reduction using Levi Drives and a diesel engine in the range between 40 and 55 % in liter used.

Cost wise the gap might even be wider since the outboard powered boat uses petrol and need 2T oil and the Levi Drive boat needs only diesel and a bit of lubrication oil. Prices for diesel is in most countries below the price of petrol.

Since the consumption tests results are still far apart (40-55 %), we want to do a final consumption trial around Penang island (45 miles). For this we would like to recruit a second boat coming out of the same mold and equip it with a 60 hp outboard engine. The task for this two boats are to go around Penang Island at the same speed side by side at a comfortable speed of around 22 knots. The fuel consumed will be measured at the finishing line.

My question is: "Is this a fair comparison"? or I need to do a correction for weight or any other factors? The diesel engine version ,for example, is much heavier but need less fuel to carry.

My present assumption is that the two boats doing the same work. Only the
fuel consumed matters.


Best Regards

Rudolf Scholz

[marshmat]

It seems as fair a comparison as any, to me... same hull, same load, same route at the same time, only difference is the powertrain. Provided both drivetrains are correctly propped for this boat, you should be able to compare them on a fairly even basis.

[xrudi]

Dear Sir,
We have executed the fuel consumption test with this two baots and the result is that the Levi Surface Drive boat uses 52% less fuel than the outboard powered boat. Our test report is attached.

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.

This result was archived with an second hand Isuzu marinisied diesel engine. Using a new Euro 2 certified diesel engine should give a larger margine.

Best Regards

Rudolf Scholz
Naval Architect

[Frosty]

your economy was due to using diesel over a 2 stroke.

[xrudi]

Dear Jack Frost,

Very interesting theory. Can you prove your remark?

Cheers Rudi

[Frosty]

You want me to prove that diesels use less fuel than petrol 2 strokes?

Is this news to you?

[Syed]

True comparison would be same engine, same boat with different drives (propulsion systems)and carried out by neutral bodies. Comparing things with more than one variables is a tricky business.
Isn't it some thing like an ad?

[Frosty]

Rudi

Are you sure you have the correct figures here. 10 miles at approx 27 knots is just about 20 minutes. In that time you used 9.7 liters of diesel??

That means your using nearly 30 liters an hour for a little speed boat?

Equally as confusing are the figures on the 60HP Yanmar. You are suggesting 60 liters per hour at what would be half throttle.

[xrudi]

Dear Sir,

Yes, I'm sure that I have given you the right figures. Even if the distance traveled would be a bit longer, or the speed a bit less, it does not influence the result, since both boats were traveling side by side.

The max speed at full throttle of the outboard powered boat was maybe a bit higher at flat water (28 knots compared to 27.7 knots) but when we get into some waves this advantage diminished.

I tried to get an independed body to witness the trial (Marine Police, Jabatan Laut, Fisheries Department, Fisheries Development Authority of Malaysia), but nobody could be moved. They told me that is not their job.

Since we want to determine the fuel consumption of an Levi Drive powered boat and compare it with an outboard powered boat, I agree with the gentleman a few e- mail above, the test was a "fair comparison".

Both boats doing the same job "traveling over the same distance at the same speed". We are interested in the economics and the ecology of the boat operation. Less fuel burned the better for the environment and 52 % is quite a chunk!!!!

I attach some spread sheet with an economic model a friend and customer has given to me a while ago. This model shows more or less similar results.

Try it out and feel free to use your own figures.

Best Regards

Rudolf Scholz

Naval Architect

[Frosty]

Rudi

You missed the point of Sayed who was saying it is not a fair comparison as too many variables were involved.

If that is your consumption then that is terrible fuel consumption. My 44 foot cat at 14 tons with 500 HP uses 35 liters per hour at 17 Knots. This vessel has my own design of surface drives.

[ron17571]

The trwo stroke is hard on gas to start with,most people understand the diesel is easier on fuel,but the added cost and weight is what keeps most folks away.im curious,direct drive to from the engine to the surface drive unit,or what?

[Raggi_Thor]

Something wrong here, a 55HP Diesel shouldn't be able to use more than 15 liter/hour and a 60HP 2 stroke maybe up to 30 liters/hour?

[Raggi_Thor]

Why not do the test again with same engine and surface drive vs traditional drive?

[Frosty]

Yes that would be a very interesting test. How about it Rudi?

To get back to the fuel consumption I was always under the impression that a diesel used 5 gall per 100HP--A petrol was 7 galls per 100HP and a 2 stroke 10 Galls per 100HP.

You say you are sure on the figures, well that would mean for a 4 hour fishing trip Thats 2 hours out and 2 hours back in you would need to carry 120 liters plus safety margine---- say 200 liters for an afternoon trip. Jeees

Im sorry but you are wrong,-- can not use so much fuel, are your bilges full of diesel.

[xrudi]

Dear All,

I agree one test is not representative and the distance run was a bit short. The defender " the outboard powered boat" had a great advantage since it used a brand new 2 stroke engine and the boat bottom was absolutly clean. The boat had just been in the water for 2 weeks.
The challenger had an old second hand engine and all what was done since it was taken from the scrap yard was an oil change. Maybe we should do the nozzels and injector pump and the measure the compression before doing a new test.

But I think it will not change too much on the magnitude of the saving percentage.

I'm not sure what would be an considered a fair test. The convensional inshore fishing boat in Malaysia is a 25-26 foot boat with a 2 stroke outboard on the back. They have about 40 000 units at work.
I was asked to test against:

0) a 2 stroke outboard powered boat,
1) a 4 stroke outboard powered boat,
2) a Mercuisere inboard powered boat,

If you have some more suggestions, please let me know. I suggest to carry out the "Around Penang Challeng" (about 45 miles) but I would like to have some sonsors and organizers.
Our fishermen tell me " Why do you want to test this boat again, everybody knows that it saves fuel". They need some public attention and some prize money to make them move again

Since Malaysia is a bit difficult, maybe I should move the testing to Thailand and organize a "Around Phuket Challenge" instead

The island hopping boats of Phuket with their 2 x 220 hp 2 stroke outboard engines would benefit tremenous from these fuel saving invention.

Attached an earlier test result. I can't get any good maps of the river area around Bukit Tambun to check the distance traveled.

Please feel free use in the economic model your own figures. (My last e- mail)It was given to me by my friend Pablo from Mexico. It shows more or less the same result.
Cheers Rudi