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

[Frosty]

It dosent matter if the engine was old or needed a tune up.

It dosent matter that the course was a little longer or shorter or the times were a little inacurate.

It doesnt matter if you take your tests to Thailand.


Tha fact remains that you are about 300% out. If you had said .97 galls instead of 9.7 liters it would be about right.


It also still remains that your outboard consumption figures are approx 300% out too.

[Quicksilver]

Now I did a test, I ran my toyota sedan (154hp) versus my ride on lawn motor (10hp) around an oval track. Oddly enough the toyota ran a full 280miles farther than the tractor on a tank of gas, of course I didnt take the deck off the mower first and the toyota had fresh tires, but wow who would have thought

Very similar results hmmm.....

[Frosty]

yes Quicksiver I agree it is a test of nothing. making comparisons like this is pointless, it doesnt say anything at all and there is no conclusion.

Testing an old deisel with any drive against a modern new outboard is pointless and predictable.

To make a proper comparison takes knowledge of the engines itself and needs understanding of what is being compared.

The example posted does not do this. Even if the figures were right!!

[Raggi_Thor]

I would think that a traditional drive, under the hull, is more efficient than a surface drive at 27 knots. That would be an interesting comparison.

[xrudi]

Hi,

Wake up guys to the real world !!!

For a consumer all what counts in the end is what it costs to transport a boat with a certain load from point A to B at the same speed. Using our system costs in this case about 50 % less. What is there to dispute?
What a great success!!

It is known fact that surface propulsion is 15-20 percent more efficient that a conventional drive. This test were done already 20 years ago. No need to do them again.


Best Regards

Rudolf Scholz

Naval Architect

[Raggi_Thor]

OK, but when your numbers are so strange, people get worried.

[Quicksilver]

It's not even that I'm worried, it's more of why say it if it's a known fact. Obviously, a surface drive should have better efficiency at planing speeds than an outboard motor. In fact it's so obvious I'm not going to bother saying why, the info is all over the place.

Some people may know, I am a boater, but as of now I'm into model boating. If one were to use a model outboard motor vs. a model surface drive on exactly the same power the surface drive is going to do ridiculously better, in run time, speed, and reliability. Yes, they're models, but actually they can be a better platform to do test like these. The equipment can be exactly the same, with the exact same hull.... etc etc.

As mentioned a standard drive would be a much better comparison, it would be even a good test for models, the only draw back, were out for fastest speeds, and we know in that aspect the surface drive beats all. In a full size boat at cruising speed, this test would be a great comparison.

With all of us here, pointing out the flaws in this test, yet admitting your results should show, what they show and you admitting it's already a known fact, than why display this faulty data for all the world to see?

[marshmat]

So might we suggest an improved test:
Take two identical hulls. Put identical engines in each. Hook one's engine to the surface drive and hook the other's engine to a properly matched I/O. For example you might use the 3.0 four-cylinder found in just about every 18' runabout, hooked to the Merc Alpha on one boat and the Levi drve on the other. Put appropriate propellers on both, mount fuel-flow meters, and do some boating.
Grady-White did something along the lines of your original test a few years back. They took a 27' Sailfish, put twin outboards on it; then took an identical hull and gave it a single Volvo duoprop diesel. Needless to say the outboards were faster, the diesel went farther on the same size fuel tank. Which to buy? Depends on the buyer's preferences.
Surface drives are notorious for being a pain in the butt at sub-planing speeds, even though they can be very good at higher velocity. People have been skeptical of your results for a number of reasons. It can't hurt to investigate further.

[Quicksilver]

seems like an actual test ^^

[Frosty]

Ok so you've posted some figures, and shown that your drive uses less than the outboard that you tested it against.

You say this is a success, it is not. Your consumption figures are imposible before you start making comparisons. They are not realistic yet you still feel we should accept them.

You can test again all you want I shall be reluctant to believe them. To do tests such as this needs credability --I think yours is damaged.

It is you sir that needs to wake up to the real world and realise that people (especially on a forum such as this) will not accept wild unrealistic claims and shoddy figures.

Do you accept that a 55HP diesel can not use 30 liters per hour or are you quite happy about that?

[xrudi]

Dear Mr. Jack Frost,

I don't think we will bent, change or alter our figures because you don't like them. We don't have problems to live with your opinion.

Please continue to give us your comments but I suggest you use moderation in raising it. You might offend somebody sometimes.


Best Regards

Rudolf Scholz

Naval Architect

[marshmat]

Rudolf,

The test you describe in post #3 has two boats running 10 miles each at 27 knots- a 22 minute run. In that time you claim that a 60 hp outboard used 20.2 L of fuel and that a diesel that seems to be around 55 hp used 9.7 L. That's 55 L/h for the outboard and 26 L/h for the diesel.

55 L/h is around average for a 150 hp outboard at WOT. It is almost three times too high for a 60 hp, few of which are capable of burning more than 20 L/h. 26 L/h is also more than double what most 55 hp diesels are capable of consuming, at least not without pumping raw fuel directly into the exhaust. Hence why Jack, and others, are skeptical.

[Quicksilver]

Ok, I'm acting like a consumer and really trying to figure this out. Not that the math is tough, but I'm trying to figure out what your trying to do here.

I'll say this, your drive looks very nice and I'm sure it is fuel efficient. I'm also sure it would be more fuel efficient than an outboard.
------------------------------
Although the figures make no sense, I'm going to ignore that and try to help you.

So you want to make your test better.

Here, you could do the same test but you've got to ditch the diesel, since your not going to find a diesel outboard(unless I'm wrong). Use the 60hp petrol motor outboard vs. the levi drive with a 60hp petrol engine. I know this isnt efficent as the diesel, but it will make a fair comparison.

Also when marketing the product using that test as an example, you can say "but if you use a diesel engine range and efficiency will be dramatically increased."

You also need to compare cost of the two drive systems. If your levi drive with motor is more expensive than the yamaha, you can make a comparison by offsetting the cost of fuel.
---------------------------------------------------------------------
However you cannot market a drive based on a test using two completely different engines(diesel and petrol) All it proves is that diesels are more efficient than petrol engines, which we all know. So if I read your ad, I'd most likely say to myself, I've got to sell my outboard and get a diesel, but I'm not going to think I need a Levi drive. I'm going to go buy that diesel motor and put in a standard subsurface drive, which will dramatically improve my efficiency and I dont need to spend money on a fancy surface drive.
-------------------------------------------------------------
Now I'm speaking as a scientist and consumer and not a naval architect. To test something like this everything must be as similar as possible and you must be able to repeat the test with similar results. You can even include the diesel boat in the test, but as a secondary test. Run three boats whatever, but you have to test using either two diesel engines or two petrol engines and it would really help if they were the same.

Seriously I'm only trying to help, telling me I'm wrong and need to wake up is not going to help you, being I'm a person and a person that might want to buy your product. Remember your trying to convince us, you may know what you want to prove but you need to examine your method.

I wish you all the luck in the world but I hope you heed our advice and if you want talk I'd more than glad to.

~QS

[Frosty]

Yes I agree with Quicksilver here, infact I think you should refer this to your designer Sony levi who will guide you through this difficult stage.

I think you should read up on some engine test procedures before making any more tests yourself and refer to your engineering department before you do any more damage to the companies credability.

Certainly I advise you not to publish your test figures anywhere that matters.

You mentioned before that you wanted some one to supervise the tests. I think this is definatley the way to go for the future .

[Raggi_Thor]

The total cost is interesting.
In Norway you pay 15.000USD for a Mercruiser 3.0L 135HP petrol engine with sterndrive, and 25.000USD for a 120HP Diesel with the same drive.
So you have 10.000USD (+ the capital costs) buy extra fuel, that is 6000 liters of petrol or 1500 gallons if you like.

[xrudi]

The general situation

Malaysia has about 40 000 resgistered inshore boats using outboard engines as their propulsion system. These fishing boats are the back bone of the protein fish supply in this county.

The situation is similar around the world in the area about plus - minus 30 degree from the equator. These fishermen and their families lifing in poverty on the edge of society. One way to make their live more bearable is to reduce the running costs of their fishing operation. This goes hand in hand with the reduction of the eviromental impact which should be one goal we should all have.

We found one solution to this problem. Our Levi Surface Drive LD 170-150 is

- cheap,
- last long,
- can be repaired by most village workshops,
- is very fuel effiecient 50 %
- the diesel engine spare parts can be found at any scrap yard
- has good shallow water capability
- can take local fisherman's abuse.

The problem at the moment is the first investment costs which should come down. (See also our spread sheet a few mails above)

The 60 hp outboard powered boat costs about 20 000 RM.

Our complete test boat costs 35 000 RM which is about 10 000 $ US. (3.4 RM = 1 $ US). We have, of course, few new propeller holders (drives) on the computer which promise a cost reduction of about 40-50 % but this is still not enough.


The purpose of this test was not to show that surface drives are more efficient than outboard engines or I/O drives. I think this is commen knowledge.
I wanted to show that there is a remendous cost saving potential by using Levi Surface Drives compared with an outboard engine.


Best Regards

Rucolf Scholz

Naval Architect

[Frosty]

Yes rudy exactly ,--we are all aware of this and what your trying to do.


Your fishing friends will not buy your drives with figures like this ,let alone get to the comparison with an outboard bit.

You say they all use these outboard engines now so I am sure they they will be aware of the consumption of them.

When you tell them that a conversion will improve consumption to 27 liters per hour, I am interested to know what they say.

Any engineer will recognise these consumption figures as nonsence, I wonder why you dont. If the consumption figure are nonsence then it doesnt set up a very good stage for accepting any thing else you say

If you wish to continue publishing consumption figures of a 55Hp diesel and a levi drive using 27 liters per hour go ahead. I am trying to help you but if you insist on these figure being correct the let me be the first to congratulate you in designing the most uneconomical drive system on the planet.

I sincerely hope you now understand what I am trying to say to you.

[Quicksilver]

I keep wondering if hes using the wrong units, like pints :) I dont know. It times like this when you wish there were a chat room.

[Frosty]

I just googled 55HP Isuzu. I dont intend spending a lot of time with this but I found a 37KW Isuzu driven 55HP generator. Quite likely the same engine but never mind. To educate Rudi about diesel engines

Fuel consumption of the generator at MAX output is 10.5 liters per hour!!!!

At 1/4 output-- fuel consumption is 4.2 liters per hour.

Yours Rudi,- is you say 27 liters per hour !!!!!! --its not the comparison its the amount used.

I dont believe you have done a test. I am begining to think you are making it up. If you did you should have googled some credible figures at least.

[FAST FRED]

"It is known fact that surface propulsion is 15-20 percent more efficient that a conventional drive. This test were done already 20 years ago. No need to do them again."

Guess thats why we see so many container ships , oil tankers and passenger cruise ships with this drive?

In a tiny boat that runs at high speeds a half out drive may produce a higher top speed , but not for the rest of the world.

FF

[Quicksilver]

Seems harsh, I would assume he was talking about planing hulls only. I think it insulting to think he meant also displacement hulls, such as oil tankers. Just my 2 cents, I thought we were trying to help him. Not too mention I dont think the guys at Arneson would like their boats being called tiny.

Guess you have a bone to pick

[Frosty]

Its a fact that some times the surface drive is just not understood. It is very different and so is the way the propeller works.

There are a few kids here in the marina that have bought small model boats about 1.5foot with twin surface drives. They are approx 25 dollar The simplest imaginable drive, with no rudders. They turn by slowing one engine. They Perform beautifully, easily making tight turns left or right.

This as quicksilver says can be trasformed into the big world.


The benefits of surface drives over outboards for small fishing boats is questionable in my opinion.
I am very envious of outboard owners who can lift the engine to clear the sea water they sit in. I have to dive, scrub and scrape monthly. Should you have an engine fault the whole outboard can be removed within the hour and taken to a workshop, and even use a spare engine whilst work is done, or even borrow one. Not to mention the ease of changing a prop or clearing it of plastice bags etc.

If two is decided upon it is an easy matter to shift one over and bolt on another.

The outboard is a wonderfull thing and will remain so.

[Quicksilver]

it's unfortunate you're right Jack, I'd love to see people using greener engines, but sometimes you have to wait for technology to catch up. The outboard is better for fishing boats, you need easy maintenance, maneuverable at low speeds and easy repair. Surface drive not quite as good in those jobs. Not to say the Levi drive isn't good.

[xrudi]

Dear Mr. Jack Frost,

The result of 52 % fuel savings of a diesel powered Levi Surface Drive powered boat over a 2 stroke outboard engines powered boat is quite a great success. The future will show that this system will succeed.

I try to understand the reason why you try to meddle around the result of our fuel consumption test. The above stated result is clear and does not need any interpretation.

If your own results differ from ours, please let us know what you have done.

Our test condition was clearly stated and quite simple. Here again:

- two boats of the same mold
- one with an outboard engine,
- the other one with an diesel engine and a Levi Surface Drive
- over the same distance
- side by side (meaning at the same speed)

The fuel was checked after the run.

I have also given some approximate figures about the test run (like speed and distance) to give the reader a general picture about the test conditions. I explained in one of my e- mails above my estimation about the tolerances of this figure.
In your basic mathematic approach you might simply have forgotten the figure two. Please check your result thoroughly before you publish it so that you might not jump to the wrong conclusion again.

Best Regards

Rudolf Scholz
Naval Architect

[Frosty]

You do not have a 52 % of any thing your figures are rubbish.

You may have a good drive, I dont know, but with some one so stubborn you are going no where.

Why cant you just google the correct figures for an Isuzu 55Hp and accept, then we can continue in helping you.

If not you continue on you own from here. If you have dictionary look up 'bigot' very interesting personality.

[Quicksilver]

my patience is growing weary as well. I think he's a computer or some kind of robot.

[xrudi]

Dear Jack Frost,

Of course we had 2 runs over the test distance ( going and comming back, easy).

To help you with your mathematics 20 miles at 27 knots is about 45 minutes. The diesel used about 10 liters during this time. In an hour it would take bit more 10*60/45 about 13 liters/hour:) :)

But I said in some of my e- mail above, this figures should not be used this way.

Best Regards

Ruolf Scholz

Naval Architect

[Raggi_Thor]

Seems like some of us didn't see that the distance was 2 x 10 miles...

Anyway, you should follow the advice of using a petrol engine with your drive and then compare with the outboard. Otherwise you are comparing diesel vs petrol.

[Frosty]

I see we havnt got very far in the few days I have been away.

So I see the problems of the confusing fuel consumption figures can be blamed on simple poor communication, (describing the test results unclearly). I appear to have not been the only one that was misled.

Making your tests of a diesel engine against a modern outboard didnt impress any one here. I have to say that I am a little confused at why this should have impressed a Naval Architect.

If your expecting these figure to impress your fishing community also, I think you may have just waisted your time.

Seeing as you already have a deisel motor I personally would think an interesting and clear test would be diesel+shaft compared to deisel+levi. Assuming the correct propellors for both configerations are carefully chosen.

[Frosty]

It would appear that Mr Sonny levi has his drives in other places.

I read it as surface drives being suitable for large commercial displacemnt ships.
It does appear that a lot of people feel that surface drives are only for high speed vessels. I myself have not agreed with that having a 24 knot surface drive boat with wonderfull vibration free economic boating.

These Flexidrives however do seem to be built differently than the Malaysian equivilent.

http://www.flexitab.com/eng_flexidrive.htm