This table values say that between 2000 and 5000 rpm, the Durajet is only 7% (1) less efficient than the tested propeller (in fact 7% more rpm needed to reach the same prop speed). Durajet do not precise which type of propeller it was. Probably not an efficient one to give Durajet a chance.
(1) (7% + 14% + 3% +5%) / 4
Unfortunately, not usable as is. As @borntosurf222 said earlier, those potential candidates have to be scaled down for our use and still to be tested 
Hmmm bad Iām getting close to my finished build but this is necessary
Watch my build pls
Orderā¦ 
20char 20char
Is it your 156mm prop ?
can you prove the graph is false?
Which diagram? I seem to recal the durajet data was slightly contradictory.
forums are peopleās opinions but faking a graph is illegal and could result in fines or a lawsuit.
false advertising, bait and switch, misrepresentation and so onā¦
the durajet is NOT a jet engine it is more what a ducted fan is to a propeller or a bypass turbo prop for exampleā¦I have no desire to argue fyi just to learn 
Yes, with simple logicā¦
Very few outboard manufacturers bother with Durajet. If it was the best, everyone would recommend them or use them.
Now for simple scienceā¦
True I have a idea now for a good duct and my build will be finished next week. I will take it one time off for max speed test.
Yeah. Same 156mm prop cncād in China. US$150ish plus shipping.
Who is faking what ?
Jezza I see the flaw in your logic. Do you have any formal training in physics, fluid dynamics or engineering?
You need a good understanding of wing tip vortices to understand this.
Fluid dynamics and compressibility, withtou that its like trying to understand quantum physics without calculus.
Jezza is convinced Durajet faked their graph.
He maintains people have proven his theory from and said quote:
If thatās from durajet itās a load of rubbish. On forums itās already been proved to be Les efficient. If it was more efficient, every motor company would abandon STD props.
and this:
If thatās from durajet itās a load of rubbish. On forums itās already been proved to be Les efficient. If it was more efficient, every motor company would abandon STD props.
I personally take a graph published by a manufacturer with more rigour than āforumsā but that is just me. Granted durajet has a vested interest but lying in print can be extremely expensiveā¦
Lastly, he is missing a key point but I am patenting the IP so I am not at liberty to explain it, nor do I feel it is my responsibiiilityā¦lol
cheers
Piotr
It was also pointed out that important details were missing from these graphs. If you struggle to be 7% slower at the cost of an extra 15% fuel consumption (or AMP drawn) the number of interested customers will necessarily be low if safety is not the goal.
When could we see the proven benefits of this ? Could it be adapted to efoils ?
Yes in all actuallyā¦
But you donāt need formal training to to understand the simplicity of it. A prop with no duct has zero added resistance at high speed.
Durajet has a huge amount of added resistance at high speed. The advantages durajet offers would only be at low speeds and in the realms of safety.
If ducts and jet-drives added benefits in the realms of high speed, all powerboats would use them for racing. Itās that simple.
Your fabled graph doesnāt even indicate what pitch propellor they tested with, which is a huge factor to consider.
If you want to attempt to prove me wrong, build or buy a durajet.
Ah so I managed to find the dimensions of the prop that was used for the graph!
Durajet deliberately under-propped the the engine. They used a 13.5" x 11 pitch prop.
That motor normally uses a prop with a pitch somewhere between 13 - 19. That will make a HUGE difference in the stats!
In Canada we cannot have a propeller. So the proven benefit is you are not risking a huge fine, never mind missing fingers and toes.
Jezza has replied as well so I will address my point in that reply since he is bringing up more esoteric information.
