Is it possible to design a surface propeller with an high diameter and very low propeller turning in order to fit a 3 kw high efficiency solar boat?
Which is the parameters to consider in order to define if there is any convenience to use a surface propeller instead a traditional one. Alberto Attached photo shows a surface prop I experimented with to understand operating conditions. You will need a very special boat to achieve 20kts with 3kW with on-board solar collectors. Location: italy Efficient low speed semi submerged props In 2005 I experimented, with Genoa and Naples universities, three different designs for five-bladed large diameter semi submerged propellers. The research was a comparative one, aimed at finding out if an already optimised conventional fully submerged twin screw installation, on a displacement vessel, could be beaten. We choose twin vs twin, counter rotating, in order to avoid the drawbacks normally associated with single partially submerged props. All trials were conducted on the scale model of a 73 mts lwl fully displacement ship, with a bulbous bow and dry transom stern. We asked Renato Sonny Levi, an undisputed master, to design the three 'challenger' surface props and the Naples university tank to modify the ship model to take the new drive system.
During the entire work, we were continuously recommended by many experts (famous propeller designers and builders, lecturers from the university, ship designers etc.) to drop such a stupid research and to avoid an useless loss of money and time. Sonny designed radical props, even if there is no knowledge at all into this area of surface prop design. The ship model was towed naked (no appendages) and then all final trial were run in self propulsion mode with each set of props, at different speeds, different displacements and all the like.
Regardless of the not perfect prop to hull match, a consistent certified increase in performance was achieved, reaching a +13% compared to the ?traditional? optimised screw propulsion. The project led in fact to a worldwide patent, hold by Flexitab (my own company) which has recently been entered in an European funded research program.
So I feel that your project should be fully feasible and I am convinced that you can beat, with a properly designed slow turning large diameter partially submerged (surface) multi bladed propeller, in a twin counter rotating set up, any submerged prop, at any speed. Conversely, I am not surprised that a single, large diameter, twin blade prop, with not optimised blade design, in ?surface? mode, should not work properly and produce poor performance.
The two bladed prop had such low efficiency that I did not bother even trying to measure it. Originally Posted by brunello We asked Renato Sonny Levi, an undisputed master, to design the three 'challenger' surface props and the Naples university tank to modify the ship model to take the new drive system.
Originally Posted by Rick Willoughby I can get 85 to 87% efficiency for lightly loaded boat props.
In Rick's case the loading is very low due to limited human power and very large diameter of the propeller.
The significant point is that the upper limit of efficiency for a submerged prop is over 90% while the upper limit for a partially submerged prop is about 70%. The overall design of hull and prop to achieve the efficiency potential wrests with sound engineering knowing what contributes to losses. Far better efficiencies are possible with lighter loadings of planning boats or very low drag boats like yours.
Joakim If the solar boat is going to achieve 20kts with 3kW it will have a lightly loaded prop. None of the partially submerged prop data I have seen would come close to matching that efficiency. If the solar boat can really reach 20 kn with just 3 kW, it could use a very small propeller with good efficiency. Having 3 kW of solar power requires close to 20 m2 of surface area, which would add weight and aerodynamic drag and also probably spoil weight distribution of a planning vessel.
Location: italy Pictures of Tank testing in Naples by Flexitab The data discussed in my previous message is not available online and is part of a research program which is still very active today, I attach a few pics to show what we are working on. We think that quasi propulsive efficiency, or what you can actually achieve with a drive system physically installed onto a vessel, is what really matters. The Flexidrive H Drive, developed for heavy displacement vessels, has no appendage drag (yes, it does matter) except for rudders, and the thrust line is horizontal as the axial flow into the prop disk is. There is a lot of work to be done, I know, but note that we went straight into two very reputable universities, Naples and Genoa, regularly doing commercial work, explained our goal and challenged them to choose one of their best self powered ship models, with twin submerged counter rotating props.
Flexitab is making a huge economical effort to make these advances and patent them worldwide. We are now in a very advanced stage of CFD virtual replay of the trials, which is matching very well with all test data. I see a fundamental flaw in your work in that you are setting up the props to give the very best efficiency possible from new technology and drawing comparisons with old submerged prop technology.
Existing ships propellers are the result of evolution in a period when fuel was in great abundance and efficiency was not a significant driver. To make a realistic comparison with a submerged prop you need to start with a clean slate and target highest possible efficiency with that technology. When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Copyright © 2014 Tattoo Design Bild, All trademarks are the property of the respective trademark owners.
Guest625101138 Previous Member   I have done the attached sketch of the boat you describe. The boat drawn will require 17kW to do 10knots if the propulsion can achieve an efficiency of 75%. I have been reading with great interest this topic on propeller design and electric outboard as I am looking at converting my aluminium dingy to electric propolusion.
I live in Perth, Western Australia so availabilty to your full range of products may be limited.
You really need a good reason to spend the money to replace a petrol outboard on a small dinghy intended for planing. For AUD3000 you could get lithium batteries that would weigh much less and enable full power for about 50 minutes.
Also be careful with things like static thrust on electric outboards compared with combustion engines. You will find most of the developments with electric powered boats are in hull design where the designer starts with efficiency in mind at the outset. Location: Australia Electric propulsion for dinghy Thanks for your valuable reply Rick.
Location: North west UK Thanks Rick for your reply, may i point out that the boat will be used on the british canal and riverways system and i know that there are several boats of equivilent or larger size using quite a simple system driven by lynch motor.
Location: france If you accept to run your boat only when wind and water stream is calm, energy need will be significantly lower. Location: finland using javaprop using javaprop for finding props for electric boats. There are a few instruments telling the knowledgeable engineer (or boater) what the present tendency may be, but that was it.
In case you try to spill your nonsense the next time here, be sure I will not reply, except with violence! Every EFI engine outboard, inboard petrol and diesel say over 100hp comes with either std or accessory fuel computer which will read any scale you like. If you buy a small boat these days many come without fuel tank gauge as they know the outboard you put on it will come with a multifunction gauge where you tell it your tank capacity and it will then tell you how much fuel left, hours to empty, how much to refill with, lph.gph, mpg, lpkilo etc etc. My brother in law has a ski boat with a Honda 150 ( gutless wonder) and it is amazing how accurate that is when you refill and the gauge tells you how much to put in.
For Mercury equipment you have to use theirs or garmin ( I think )as they went on a their own re can bus protocol.
I'm sure with outboards you can probably get this down to maybe 50hp as a guess, before I check that is.

Sure you will appreciate once you have the data you can display it in whatever units you choose, if yours is a dial, ok fixed but if a digital display you can choose anything. The surveyers work in mm so all their data and instructions to us is in mm but as you say with the current set up the vessel cant be that accurate if we are only using DGPS but when you add a couple more position fixing systems then we can be much more accurate but only once on site as the other systems are fixed either on the bottom or a platform. So if they sent us into the middle of the sea to drop something we could only do it accurate to say plus or minus 500 - 700mm on a good day or should I say the DP system would be telling us we are hovering around a 1m circle at best and can be 1.4m on an average bad day. So the answer is we cant be accurate to the mm but as far as a surveyor is concerned he is on a building site and thinks he can. I guess after the first bit of kit is dropped on the bottom that sets the position and everything else is put in relation to that. The clients also install other systems on board that do position fixing that we can see and also sends our postion back to them so they can tell us to move before we even know we should move. They will also supply a drawing ( couldnt call it a chart) in metres ( usually with scale of 5mm to the metre) that will have all the installations and sub sea etc drawn in.
We have a perspex cutout of the vessel with crane swing etc to scale and play like kids to work out where we can fit and what you can do. You really need this in 3D as the depth for umbilicals etc comes in to play so we make our own profile drawings of things like if we are here can say an ROV get to there without us moving etc which way will the stream pull etc etc. I am aware there is another method of differential data for GPS called XY or something ( A Norwegian with bad english was trying to tell me) that does pull the error very small but is very expensive to receive.
One other piece of data that you can collect but I've only seen it on large engines is turbo speed.
All things being equal and new you can calculate the air density by the rpm of the turbo as rpm goes up when density goes down. He told me on the newer electronic engines, when on sea trials the manufactuers technicians can always say, yes we have x power and he says they are never wrong, how? If they have all the parameters of an engine, mep, egts, boost, fuel flow, blow by, water, oil temps, ambient air temp and pressure, turbo rpm the figures slot into the computer that says you must be making x power as there is no magic to losing or gaining power less splitting hairs over the calorific value of the fuel so you must have x power. The cylinder pressure sensors also graph time, crank angle to pressure so if there is a problem with fuel or valve timing the computer will tell you its not normal. This stuff is not only for big engines, I know some guys that run graphing cylinder pressure sensors on their racing outboards. So add this to your CPP installation and you can know exactly what is going on with your engine. The EPA in the US is trying to mandate that car engines flash a warning up if there is just a single missfire.
The manufactures have said no way but are working on it some trying cyl press and some by monitoring the spark plug voltage curve.
Originally Posted by powerabout Here's a photo of the some of the gauges that dont exist ( well in Apex's 1970's world anyway) That gauge to the right is for a self adjusting prop! Of course electronics can tell you a lot, and some programmes even calculate consumption on a more or less reliable base. There IS in fact a gauge telling you the tendency on engine load, I mentioned that more than once! Originally Posted by apex1 Of course electronics can tell you a lot, and some programmes even calculate consumption on a more or less reliable base. What exactly are you building Gulets with the worlds last supply of mechanical injected non compliant engines? A short look at my Gallery would give you a idea about at least some of the vessels I build.
To add to what Rick has said about outboard motors, it might be easier (and cheaper) to convert an old outboard motor. The reason I suggested the outboard over an inboard system is the design flexibility it gives you. I think you will surprise people with the performance that can be achieved with the small boat and electric motor if you keep the weight down and make an efficient propeller.
With high efficiency propellers you get high bending loads in the blades if they are run at an angle to the flow.
With an outboard there is no need to put a shaft through the hull and all the complexity of leaky shaft glands.
Do you actually intend to build the drive unit or are you only required to submit a design? Originally Posted by bairachtn yes i am going to build the control system Do you intend to actually use the control system in an operating boat? Location: Greece Mr rick, the pictures of the boat i sent you, is the boat we are going to make electric, in a few days or weeks i am going to buy the motor, propeller, batteries and the other stuff to start building the boat, thats why i need your help, the control system is going to build after january, and we expect about june to be able to use the boat, i have a question for you, with savitsky method i have calculate Re about 5*10^6 to 6*10^6, is the Re values suitable for my application? You need to be aware that you will have difficulty buying a propeller that will give best efficiency. If you spend some time adjusting the airfoil angle of attack and other parameters like speed you should be able to produce a propeller with better than 80% efficiency. The gain in efficiency is offset to some degree by the extra drag from the nozzle so this needs to be taken into account if you want to shroud. Location: Greece here are some results for Re# E193 300000, and 0 degrees,what you think?
You now have to tie in the thrust produced to balance the drag for the speed from those curves I supplied. Location: Sweden Propeller Torque and Propeller efficiency I am designing an electric motor for sailboats. Another question in question is what differences in propeller efficiency we get with higher RPM and smaller prop versus lower RPM and bigger prop. Location: New Zealand Hi, Ian Nicholsons Boat Data Book pages 108 through 129 give a lot of information that you might find of use. If the boat is easily driven then the 2000rpm and smaller diameter could be better than spinning a bigger prop slower.
Location: New Zealand Hi, my preference for a sail boat or displacement motor boat is to go for the larger prop turning at the slower speed.
Least amount of induced drag , and on a long keel boat the prop can be hidden behind the deadwood for very little drag.
Sailboats sometimes attempt to sail , and all do far better without a speed brake always deployed . I have attached a screen image of the design page from JavaProp to give you an indication of the results you should be getting. To get this result, you need to set the options page to water parameters and select a foil profile.
The torque required for the propeller is simply the power divided by the rotational speed in radians per second. I have made an electric outboard that would suit a medium sized yacht with the appropriate propeller so I have a good idea of what you are trying to achieve. Guest625101138 Previous Member   I should add that you can use the same torque equation for the motor if you have gearing but of course you need to use the motor rpm.
Guest625101138 Previous Member   The exact information you requested in the original post is available from JavaProp in the Multi-Analysis field per attached. You do need to apply the torque formula given above to determine motor torque at the various power figures determined by JavaProp. One of the nice features of JavaProp is that you can change the rpm on the Design page and then go to the Multi- Analysis page, re-analyse to look at what power the particular prop will absorb at the different rpm.
Guest625101138 View Public Profile View Guest625101138's Gallery Find all posts by Guest625101138 « Looking for CCA type above deck, modern below, design, cold molded bld. Larger turbines utilize a system of wind sensors and servo motors to keep the propeller turned into the wind.
Design of propeller turbines for pico hydro Robert Simpson Arthur Williams This design guide is to be used alongside the calculation spreadsheets that can be Propeller turbine mixer design calculator solving for fluid dynamic viscosity given Reynolds number, revolution per second, liquid mass density and impeller diameter A turbine design speed is largely determined by the head under which it operates.
The design of cost-effective pico-propeller turbines for developing countries Dr Robert Simpson, Dr Arthur Williams Nottingham Trent University, UK A simplified propeller turbine runner design for stand alone micro hydro power generation units, International Journal of Ambient Energy, 17(3) pp 151-162, Propeller Turbine.

Windmills, or known today more as Wind Turbines, are machines designed to convert the energy of the wind using rotating blades to create power. Usually HPB's use a propeller which looks a lot more like an aircraft prop than a boat prop, so I presume a conical version would look something like this. Location: Port Orchard, Washington, USA More surface and less diameter = less efficient. Location: FL, USA Conical Propellor The first Atlantic crossing by a propellor driven ship, in 1839, used a screw invented in 1827 by Joseph (Yosip) Ressel, and later refined by John Ericsson. I suspect the conical design alexlebrit is looking for is like his illustrations, rather than Ressel's Leonardo-derived version shown here.
The aim was to achieve good efficiency at relatively low speed - I determined it cannot get good efficiency for a variety of reasons. A single large diameter surface prop, is normally difficult to tune and make efficient, mostly because of the high side forces it develops. The model had already been tested with a conventional submerged twin screw set up, in self propulsion mode, and all data were available. According to the ?experts? it would never work, since surface drives are ok at high speed only. We got all the props models nc machined from billet, tested them first in the Genoa cavitation tunnel and then in isolation in the Naples tank, using a Z-drive style pod. Matching resistance vs power absorption curves, it was clear that the props needed tuning for top performance (pitch adjustment), which in fact was not done for this first set of trials.
A lot of work needs to be done, but we feel the result was spectacular ? and a lot of sceptical ?experts? became our sponsors.
We have now developed an in house code for a full CFD analysis on a surface propeller, matching the available physical test data we have, with very good results.
I concluded that aeration, centrifugal water particle scattering and water splashing (together with the acceleration of water added mass) during blade entrance were the enemies to fight if one wants to improve efficiency. I just wanted to point out that 70% is not at all a bad efficiency in many real displacement boats and ships. The smallest racing boats (3.1 m) can reach 32 kn with an unmodified 15 hp outboard at total weight of 160 kg.
We have definitely beaten the fully submerged twin prop set up, especially at the higher speeds (due to shortage of knowledge on the lower end, where we are still closely matching). The cyclic loading of a conventional prop in the up and down position is a fact, as the angled flow into the prop disk is. What we get in the cavitation tunnel and in the isolated prop tests, is exactly what is delivered to the vessel, when installed. Their wrote the final reports, they made all tests, they were the first to be totally amazed. While I was the one with the original concept, it would have been impossible to make it work without Sonny's knowledge and huge experience, which never interfere with his free thinking approach to design.
I'd like to know what sized motors ,best type of propeller and drive system ?Also best type of batteries taking into consideration that i will be living on the boat and have all the electric amenities that you would have in a house. Also you will see with JaveProp that a big diameter prop will be more efficient the a smaller diameter prop. In my case I have the alternatives 2000 RPM and 9-10 inch propeller or 900-1000 RPM and 13 inch propeller. Generally speaking the prop diameter is related to the length of boat it is driving and the horsepower applied to it.
A sailboat is usually underpowered compared to a motor boat and a small prop just does not hack it. What I am looking for is measured values for torque demands to drive boatpropellers at different RPMs. It assume the torque to be related to the enginepower (I am interested in propeller torque, not engine torque). Tubular turbines are a fully axial design, whereas Kaplan turbines have a radial wicket Submersible Propeller Water Turbines- These turbines are the least efficient of the three styles, but also the simplest design.
Wind turbines use the power of wind to turn motors, allowing the motors to generate and store through the evolution of the most spectacular wind turbines designs in the is directly in front of the wind, the more powerful the turbine. Most wind driven propeller turbine designs make use of a Efficiency of Propeller Design on Wind Turbines _____ A Science Paper Presented to Missouri Junior Academy of Science _____ By Jacob Cogan Best Answer: Industry today addopted the 3 blade horizontal axis turbine. Instead of Design of Kaplan Turbine This design of wind turbine was patented by Georges Jean Marie Darrieus, a French strong tower that grows dramatically with the size of the propeller. The actual ship had been built after the tank testing and tank data were found to be reliable when scaled up. Already some results were quite interesting, since these props, due to peculiar geometrical factors and slow turning, showed some surprising results, departing from ?conventional? surface prop behaviour.
According to Savitsky method even those would need more than 3 kW of effective thrust at 20 kn, thus at least a 4 kW motor. Would it be possible to link it all to a generator that would drive the motors when the batteries are low , charge them at the same time and run the electrics on the boat? I would presume that any form of power drive would be inefficient and would relate to 1 or 2 HP being driven through the propeller. The "design" returns original optimum chord data, and omits modified chord data totally? The common calculations around is based on combustion engines and as electric motors have different torque curves I would like to know what torque that a certain propeller must have to be turned at certain RPM.
In most cases a larger propeller driving at a lower speed will be more efficient than a small prop at high speed particularly for displacement speeds you would expect with a sailboat.
A propeller mounted on the front of the The existing turbine and generator were designed originally to operate as a fixed blade propeller, and therefore, lacked the design features required for blade angle control. A single dimension propeller Bicamber's airfoil design makes aerodynamic products quieter, smoother running, and more efficient. The basic propeller turbine consists of a propeller, similar to a Family Hydro – a propeller type micro turbine Matthias Bissig, Antonio Di Miele of the directly coupled generator either the generator or the turbine designs Propeller wind turbines are the most common way of using one of the most abundant energy sources on Earth to generate electricity. If you've got a huge great aircraft like propeller it has to sit well below the hull to give clearance. An unconstrained open water prop for 3kW at 20kts will achieve around 90% efficiency while a surface prop will achieve a best efficiency around 70%. These propellers have normally wide blades designed to avoid cavitation and vibration and can not typically have a very high efficiency in any condition. You can download this as nice desktop wallpaper by right click and save as into your computer. If you give Javaprop values for a 1meter diameter prop at 1100 RPM with a power of 500 watt you get a positive result of efficiency about 50% and a thrust value!! Yes its time to steal some more of Larrabee's work Brad Sorensen Experts and investors alike agree that wind power is currently the most viable form of renewable energy available for mass production. In typical displacement boats and ships the thrust loading coefficient is high, since the propeller diameter has practical limits and speed is low.
Don't miss to check all from this kind of lovely popular desktop background by viewing the similar high definition wallpapers design below. Just the most basic propeller theory limits the efficiency well below the figures you are giving and above that comes the restrictions caused by cavitation and actual propeller design. I work the other way - what motor (power and torque) do I need to turn the best suited prop? Kimball(AM) An open-sourced computational tool for the I am doing research for which is the best wind propeller to use.
It seems the makers get close to fisticuffs over this nonsense figure accusing each other of exaggerated claims.

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Comments to “Boat propeller design software 4.0”

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