Surface Drive versus Outboard Engine

[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