Surface Drive versus Outboard Engine

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.

 

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.....

 

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!!

 

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.

 

Levi Drives versus Outboard Engine

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

 

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

 

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?

 

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.

 

seems like an actual test ^^

 

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?

 

Levi Drives versus Outboard Engines

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

 

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.

 

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.
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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.
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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.
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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

 

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 .

 

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.