Before we started optimising content, we got the new domain online and loaded the existing content onto the new domain.
Our client is seeking interest in his boat propeller design, rather than retailing propellers. We also targeted the misspelling 'propellor' and registered the domain name with the misspelling. When optimising content, we ensure that titles remain shorter than 71 characters and meta descriptions less than 156 characters - the maximum that will show in a Google result before being shortened. We will be keeping an eye on rankings for this new site, and expect it to start ranking reasonably quickly for the less competitive phrases. Location: Amsterdam High-Speed Jet Propeller Jet engine erupt high pressure gas at the end of the tail.
Location: Amsterdam I have so many question, and no one give a answer!!!!!!!!!!!
The language barrier is extra tough this time, maybe your translation software needs improvement. Location: Amsterdam I come from hell and am going to heaven, this is why you can't understand me. Originally Posted by waveless I come from hell and am going to heaven, this is why you can't understand me.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Location: Amsterdam High-Speed Waveless Sinusoid Propeller Have you ever saw this kind Propeller?
Location: Hawaii This device works by the viscosity of laminar flow which is increased by the weight of water falling into the v between the 2 wheels. Location: Amsterdam This device works by the viscosity of laminar flow which is increased by the weight of water falling into the v between the 2 wheels. If you were to drive a right rotating propeller, with a left rotating engine, so to speak, it would be like driving astern. Location: Arlington, WA-USA the prop would work but not be very efficient driven backwards.
It might be possible to compromise the design and develop a shape designed to be more efficient in both directions, but there no much call for a prop designed like that. Originally Posted by Petros the prop would work but not be very efficient driven backwards.
Location: Alexandria how can I know the propeller rotation direction when looking from its hub (aft.) side?
Location: Milwaukee, WI The forward edge of the blades indicates the direction of rotation. Originally Posted by abohamza how can I know the propeller rotation direction when looking from its hub (aft.) side? I appreciate if you can explain that on the photo or ,kindly, on a wooden prop if possible. Location: Italy (Garda Lake) and Croatia (Istria) It works the same way with air props. Location: Italy (Garda Lake) and Croatia (Istria) Compliments for the job done so far. But that can't be the issue here, because you airboat would move backwards if the engine was LH.
Location: Azores Pedal boat propeller specifications data Hello folks! I'm looking to build a pedal powered sea fishing canoe but found there is a lack of detailed info on ANY pedal power props. If you'd like to discuss something, please start a different thread and link to it, hoping this thread will fill with DATA ONLY! Originally Posted by MarkX Most of us know the basics already and are building our own boats, so no need for distracting discussions of the merits of one over the other, this is purely for data.
A vessel is nothing but a bunch of opinions and compromises held together by the faith of the builders and engineers that they did it correctly. Javaprop will give answers within about 5% of actual but it has a limited array of sections and Re#. Originally Posted by Rick Willoughby You can calculate prop performance within 1% or 2% of actual performance. Originally Posted by Rick Willoughby If you have an application in mind I can determine how various props will perform.
Originally Posted by Rick Willoughby Javaprop will give answers within about 5% of actual but it has a limited array of sections and Re#. Rick W It would for those prepared to learn how to use it, however most garage builder's priorities are different. Originally Posted by MarkX It would for those prepared to learn how to use it [javaprop], however most garage builder's priorities are different.
Location: Milwaukee, WI To calculate a prop you need to have the power input. Location: USA Check the archives under MCDenny in efficient electric boats.

Originally Posted by portacruise Check the archives under MCDenny in efficient electric boats.
Originally Posted by MarkX Well no, most people can't, which is why I've started this thread about ACTUAL props used in different pedal designs, not hypothetic paper mathematical program ones.
Take a few minutes to learn how to use JavaProp and you will save a lot of time trying to collate useless information.
What wind strength will you want to design for - it is not the worst case but the strength you want to operate in without stress? If you have the hull shape and the total displacement the hydrodynamic drag can be calculated.
The gearing depends on functional aspects particularly draft but it could be also the selection of parts.
Being into RC planes, the RC props are of interest not just for me but because of their worldwide cheap availability. Ultimate performance of the first prop try isn't half as important as it's general usability by people of average power output (Moderate?).
A single blade screw,auger (like a post hole borer) is the answer and has been used on ice tractors in quarries and many industrial applications and does not suffer so much damage. The image shows a Bob Drive modified for some tough work and cheap to build or you can use a trimmable shaft or Pivotal drive. But in water, what diminished return does the blade area longer than a traditional blade offer with the column of water already accelerated? Location: Eustis, FL Gonzo is correct in that the screw type of drive was tried first, but it was quickly superseded by what is now a more conventional prop. Having seen and worked on augers used in farming applications, I can say they don't fair any better then a conventional prop, but they do have so much more blade area, that they can adsorb more damage then a regular prop, before they no longer are effective. About the skrew prop we do have a fysical problem as the resistant of the big surface on a propeller like this makes the water to spinn along the prop and decreases the effect. So if you make the screw shorter and exchange the rudder axel to a flatbar this will help stop the water from the twisting issue. I would not expect such a drive to be fast but it did do a fine job of what I expected from it and would be great for those who have a constant use for it. As the water no longer are able to twist when leaving the spiral prop the centrifugal power are no longer able to throw away the water from the propeller.
What Size Prop for Mitchell 31 MK1 » Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Search this Thread Advanced Search Similar Threads Thread Thread Starter Forum Replies Last Post Does a sail act as a turbine blade or a propeller blade? At the moment at 25 kts my engines can't go over 2100 rpm, I think that my pitch is too big.
Location: Australia You either obtain new props or you get the existing props re-pitched.
Since you need to calculate the cavitation number suitable for your installation and then ascertain which is the best BAR to match your 'fixed' gear box ratio.
But as I noted above, you still need to calculate the cavitation number, and estimate the speed of water flow into the prop, from the lines and arrangement of your installation. Frosty Previous Member   Reducing diam will only increase slip and not necessarily speed --200 RPM low is perfect IMO. Location: Italy (Garda Lake) and Croatia (Istria) Another option is to twist the trailing edge of the prop blades few degrees towards upwards (towards suction side). Surely the opposite bend would significantly encourage cavitation at the leading edge of the blade ? Originally Posted by MikeJohns Surely the opposite bend would significantly encourage cavitation at the leading edge of the blade? Please note also that the above pics show 30% flaps, much more than is used for blade cupping, hence they serve for exclusive purpose of more clear visualization of various results. From some calculation that I made with my software, playing with rpm and power, I have to reduce the pitch of 70-80 mm, having a new pitch of 810 mm instead of 890 mm. I will talk with the guy that can modify the propeller, and I will see if to have a new pitch or use a 10° cup!
I?m not sure how much value your infinite foil, pressure distribution software really is in this case. You should be looking in detail at the free ends of the foils and the total pressure distribution pattern on the back of the blade.
Positive cupping always reduces cavitation at high loads, it?s a valid way of reducing cavitation even at small cupping angles that have little effect on effective pitch. I really think that negative cupping will have the opposite effect and the cavitation bubble will be trapped to some extent rather than being ?swept off the back of the blade?. Our client in Timaru has come up with a way to make the traditional boat propeller a whole lot more efficient, meaning faster boat speed, better fuel efficiency and less noise. We picked phrases such as 'boat propeller design', 'marine propellers', 'ship propellers', 'outboard propellers' for the site and optimised each page accordingly. Having made the spelling mistake a few times ourselves while putting the site together, we figured others would be doing the same (which our keyword research also confirmed).
SEO experts have mixed opinions as to whether this helps at all for SEO, but we consider it important for other reasons. If the pressure gas erupt to the bottom of a boat and form a air bad, it prevent friction between water and boat.

I then select the most interesting pictures which of course have links to full fledged sites. It is suitable for twin-hull boats that Sinusoid Propeller can put into front or middle of the boat. The prog doesn't even seem to differentiate between water and air as far as I could determine. Also seacycle, hydrocycle, cadence and other commercial HPB should give you an idea of what has been used. If you could post drawings for a variety of leisure pedal boat apps, like pedal powered Kayaks and Leisure Canoes it sure would give loads of people a concrete starting point. There were pages upon pages of people waffling but next to no useful hard info on actual diameter and most importantly, actual pitch and gearing. Once I have arrived at a satisfactory effort level by chopping it I'll then guesstimate the nearest size uncut prop. Yes it has been tried and is hard to control in deep mud because it wants to go streight ahead. I see how this works in mud or sand like a screw drive tank or RTV concept on a smaller scale. However, many assumptions are required, for someone else to do the same, and can lead to very different results.
The vertical axis being the efficiency of the prop (from the charts) the horizontal axis is the gear box ratio, and then a series of curves (calculated from the charts) of different BARs. A positive cup alone (with no change in blade pitch) will increase the lift produced by the blade and also the negative gauge pressure over the ventral side of the leading edge. What I can do at the moment is to bent the blade having a new pitch, or trying to cup the blade of 10°.
I think you need to look in detail at the pressure distribution not just a cross section of an ideal foil.
However, this will mean the new domain will need to wait out the sandbox period before starting to rank well, but the shift was an important one. We like to tell Google about new domains before doing anything else, as this gets the site out of the sandbox that little bit earlier.
Part of SEO is making sure the website converts visitors to leads, and part of that is designing a site that looks good, is accessible, and has all those other qualities that people expect from modern websites. Visitor numbers have nearly doubled since our blog was introduced and we are even ranking well for various key words from the release titles. This method jumps over many language barriers, so you could end up on Russian sites or even more exotic places and languages. When someone did think of mentioning it, they forgot to mention the gearing ratio, so the info is virtually useless in practice. In practice such data is very dependent on different sea conditions and whether outriggers are deployed or not and where the wind is coming from. The fine tuning has to be done in practice, at will, and is highly variable on many factors. You may not be able to reduce pitch any more than you already have, some props can't tolerate more than an inch of change, but reducing diameter is easy and appropriate if you are too close to the bottom already.
It is sometimes customary to let the engines over rev a couple of hundred RPM to account for typical loading conditions like fuel, beverages and peeps. The result of this reverse-cupping will be a decrease of the effective angle of attack of the flow seen by the prop blades (which is equivalent to a down-pitching), a decrease of the torque, a decrease of cavitation level and an increase of RPMs.
I'm sure it's brilliant for paper designers but it's failed my real-life practicality test. A pedal propeller boat will be powered by a kid or an athlete or anyone in between so the question still is: WHAT DIAMETER, PITCH AND GEARING HAVE YOU ACTUALLY USED.
That's the reason I don't want this thread to develop into a discussion but simply have ACTUAL USABLE DATA to make a prop for a pedal powered propeller boat. A boat propeller operation in shallow water and mud, stones, soon makes a prop look very sad.
Personally, I think you just have to live with a certain amount of damage potential in some situations.
Also, see the page 2 of the document in my previous post - it shows the reduction of peak pressure achieved by both cupping and de-pitching of the blade (my pic n.3). The effect of a positive (downwards) deflection of a flap is an increase of lift (for a fixed foil AoA) and a decrease of pressure over the leading-edge dorsal surface, while the negative (upwards) deflection decreases the lift and increases the pressure around the leading-edge area.
But, if a positive cup is accompanied by a correspondent decrease in pitch (in order to keep the blade lift constant), then the benefit of decreased cavitation may be achieved. Since you are off by just 200 RPMs, you could as well end up with the correct RPMs even after just the first step. FWIW, maximum efficency is achieved at infintessimal loading and infinite diameter at null RPM with nill BAR and immeasurable thrust. I suppose the worst case would be that of a Canoe going into wind in increasingly choppy conditions with the added possibility of braving a swell (And hopefully towing a dead Marlin from one of the outriggers).

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