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Updated last November 1, 2009

R/D: Student Projects/Thesis etc.

R/D: Student Projects/Thesis etc.      Scroll To Top Top

      Cavitation Bucket Diagrams...

      [2 Mar 01] We are French students working on foils and the problem of cavitation. In the FAQ of your web site, we have read a message of Mr Martin Grimm who speaks about cavitation bucket diagrams. We would like to find an example of these diagrams to illustrate a tutorial project. Could you help us by sending us a diagram or any valuable information? -- Mathilde Pascal ( and Ludovic Léglise (

      [2 Mar 01] I've attached an excerpt from the paper I just gave to the Chesapeake Sailing Yacht Symposium. It shows such a diagram and discusses its relevance to the hydrofoil design. I've also included an enlarged version of the diagram. I've chosen a somewhat idiosyncratic way of plotting this diagram. The X axis is often angle of attack, but I've chosen to use lift coefficient because different sections have different zero-lift angles of attack and lift coefficient is what really counts to the designer. But the biggest difference is that I have plotted velocity ratio on the Y axis instead of pressure coefficient or cavitation number. I did this because pressure coefficient is proportional to velocity squared, so it emphasizes areas of high velocity which are not of real interest. By plotting vs. velocity ratio I have expanded the bottom of the chart which is where the section will be operating when cavitation is a concern. The other thing you will find on this chart that I've never seen on any other diagram is an overlay of freestream velocities and foil loading corresponding to incipient cavitation. I found this really helped me to understand the section curves in the context of the boat's design. I haven't actually plotted it out yet, but I suspect that had I used pressure coefficient for the Y axis, the lines of constant foil loading would have been straight lines. Finally, my apologies for using English units. I'll leave conversion to metric as an exercise for you students! -- Tom Speer ( website:; fax: +1 206 878 5269
      [6 Mar 01] Tom Speer has already given you a good reply following your request for examples of 'cavitation bucket diagrams'. I will however provide you one more example which is presented in the more usual manner with section cavitation number on one axis and foil angle of attack on the other. The attached diagram has been adapted from one of the figures in a very well presented and comprehensive book on the subject of marine propellers, namely: Marine Propellers and Propulsion, by J.S. Carlton (Senior Principal Surveyor, Technical Investigation, Propulsion and Environmental Engineering Department, Lloyd's Register) Butterworth-Heinemann Ltd, Linacre House, Jordan Hill, Oxford OX2 8DP First published 1994. ISBN 0 7506 1143 X.
      There are no scales on the axes of the diagram as it is illustrative only. You can see from the shape of the curve where the 'cavitation bucket' term came from. Even though you may already be familiar with the terminology on the diagram, I will run though it for completeness:

      The section cavitation number is defined as:
      Sigma o = (po - pv)/(0.5 rho V2)
      po = Free stream pressure in absolute terms, i.e. not relative to atmospheric pressure (SI units would be Pa).
      pv = Vapour pressure of the water in absolute terms (SI units of Pa).
      rho = Water density (SI units would be kg/m3)
      V = Free stream velocity, i.e. well upstream of the foil (SI units would be m/s)
      (I have avoided using subscripts or the usual Greek symbols so that I can send you this message in plain text)

      For a foil traveling say 1 metre below the water surface in salt water, po can be calculated as:
      po = patm + rho.g.h
      patm = Atmospheric pressure, say 101300 Pa
      g = Acceleration due to gravity, say 9.81 m/s2
      h = submergence of the foil (in metres if using SI units consistently)
      po = 101300 + (1025 x 9.81 x 1.00) = 111355 Pa
      In salt water you can take the vapour pressure to be say: pv = 17000 Pa to be on the conservative side. The vapour pressure of distilled fresh water can be as low as 1700 Pa.
      You can see from the diagram that at high angles of attack, cavitation will occur on the top side of the hydrofoil (called the 'back' in propeller terminology). At low or negative angles of attack, the low pressure moves to the bottom of the hydrofoil (this being called the 'face' on propellers). If the water flow past the foil is fast enough and the foil is not deeply submerged, then cavitation can even occur when the foil is at the zero lift angle of attack. This form of cavitation is referred to as bubble cavitation because of its appearance. This cavitation occurs simply a result of the thickness of the foil which causes the water velocity to increase slightly as it passes the sides of the foil and in turn the local pressure of the water drops below the vapour pressure.
      These days, there are techniques available to design foils which are fairly tolerant of variations in their angle of attack and so can avoid the onset of cavitation. Such foil sections have a fairly wide cavitation bucket (defined by the parameter "alpha d" on the figure), though the limit at which bubble cavitation occurs may then shift to higher cavitation numbers so the bucket is no longer as deep. -- Martin Grimm (
      Follow Up...
      [10 Mar 01]We have built a model of a foil with a NACA 0015 profile. Where could we find the cavitation bucket diagram corresponding to this kind of foil? Mathilde Pascal ( and Ludovic Léglise (
      Follow Up Response...
      [11 Mar 01] Here is how you build a cavitation diagram:
      Go to and download XFOIL. This is the most powerful airfoil section design tool available. Do not think of using anything else you can download from the Web -they are all inferior to this program.
      Put in the coordinates for your foil.
      Analyze the section for a number of angles of attack, covering the intended range of operation. Examine the pressure distributions for each angle of attack.

      For each angle of attack, record the minimum pressure coefficient that occurs anywhere on the section. The cavitation number, sigma, is simply the negative of the minimum pressure coefficient, Cp. (sigmai = -Cpmin where sigmai is the cavitation number for incipient cavitation and Cpmin is the minimum pressure coefficient)
      Plot the minimum pressure coefficient vs angle of attack or lift coefficient, according to which you prefer.
      Repeat steps 2 through 5 for each section you wish to consider.
      I recommend you plot sigmai vs CL for the following reasons. If you disregard the vapor pressure of water, which is small, the critical speed for incipient cavitation at the surface is approximately
      Vcrit = 14/sqrt(sigmai) m/sec
      sigmai = (14/Vcrit)2
      Vcrit is the freestream velocity above which cavitation may occur. Note that this is a horizontal line when superimposed on a cavitation diagram. If you know the freestream velocity (boat speed) and you know the lift coefficient, then you know how much load each square meter of the foil is carrying:
      L = CL * 1/2 * rho * V2 * S
      [L/S]crit = CL * 1/2 * rho * (Vcrit)2
      [L/S]crit = CL * 1/2 * rho * 142/sigmai
      sigmai = {1/2 * rho * 142 / [L/S]crit} * CL
      Note that for any given foil loading (L/S), the quantity inside the braces {} is a constant so this is a diagonal line extending from the origin of a sigmai vs CL plot.
      Finally, to put together the whole cavitation picture, do the following:
      Lay out axes of sigmai vs CL
      Plot horizontal lines corresponding to the critical cavitation boat speeds.
      Plot diagonal lines corresponding to the foil loading for incipient cavitation. Note that this forms a grid which is independent of the choice of foil section.
      Plot sigmai vs. CL for the hydrofoil section.

      Now, not only do you have the cavitation diagram for the section, you can relate it to key design aspects of the boat as a whole. You can see immediately how heavily the foil can be loaded and how fast the boat can go before encountering cavitation. Since the grid is universal, it can be used to define the requirements for designing a hydrofoil section, which you can do with XFOIL as well.

      There is an excellent paper on the cavitation of hydrofoils in the latest issue of the Society of Naval Architects and Marine Engineers' Journal of Ship Research, written by researchers at the Institut de Recherche de l'Ecole Navale, 29240 Brest-Naval, France: J.-A Astolfi, J.-B. Leroux, P. Dorange, J.-Y Billard, F. Deniset, and S. de la Fuente, "An Experimental Investigation of Cavitation Inception and Development on a Two-Dimensional Hydrofoil," Journal of Ship Research, Vol. 44, No. 4, Dec. 2000, pp. 259-269. It shows more cavitation diagrams and also the degree to which experimental cavitation occurs at Cpmin. The agreement is excellent at the bottom of the bucket and Cpmin is a conservative estimate for the sides of the bucket. They also discuss the interaction of cavitation and laminar flow, which will be important for your low Reynolds number experiments. -- Tom Speer ( website:; fax: +1 206 878 5269
      [Date/Time=03-22-2002 - 11:50 PM] [Msgid=237110]

    Hydrofoil Racers -- Power or Sail
      Hydrofoil Racers -- Power or Sail

      Student Project: Racing Hydroplane
      [5 Mar 02] I am currently a student at Teesside University in England studying Computer Aided Design Engineering. As part of a project we have to improve on an existing hydrofoil design. The boat my team has chosen to improve upon is to be capable of racing in the 2002 Unlimited Hydroplane Series of which the boat MISS BUDWEISER is currently the title holder. Could you please advise me as to where I may find design specifications of such boats especially in relation to the cockpit area (safety) and the steering mechanism incorporated in the craft? -- Ben Coward (

      [5 Mar 02] You have an interesting project, however our site is concerned mostly with fully submerged and with surface piercing hydrofoil designs. We have next to nothing on hydroplane racing craft. I am sending a copy of this response to Leslie Field ( and to Simon Lewis ( in the hopes that they can suggest a source the design specs you seek. You may have luck by contacting directly the racing crews of specific craft or the racing association. -- Barney C. Black (

      [15 Mar 02] The American Power Boat Association puts out all the specifications for the various classes of hydroplane racing crafts. MISS BUDWEISER is in the unlimited class. I believe they are presently headquartered in Detroit, Michigan. I had some discussion at one time with a former crew chief of a hydroplane racing team who wanted to put hydrofoils on the sponsons. I believe he proposed it to the APBA but was rejected at the time. -- Sumi Arima (
      [Date/Time=03-23-2002 - 12:51 AM] [Msgid=237128]

    Info wanted on Hydróptero      ViewThread
      At 08:02 PM 4/24/02 -0400, you wrote:

      I'm student of Transport, and I have to investigate for Hydróptero. I want to now if hydrofoils and hydróptero are the same type of boat?

      If you have more informatión of characteristics, possibilities and restriccions for hydróptero, I apreciate you send me by E-mail.
      Sonia Madera
      [Date/Time=04-26-2002 - 9:00 PM]    Name:Sonia Madera, [Msgid=252390]

    Swath ships architecture Thesis      ViewThread
      Dear Sirs,

      My name is Giancarlo Raiola and I am a student of Naval Architecture at the Federico II University in Naples (Italy).

      I write to you because I visited your web site and I found very interesting all the information about Swath ships. As a matter of fact, Swath ships architecture will be the subject of my graduation thesis, so I would be very pleased if you could send me some more detailed information about them, as for example their general plans and about active motion control sistem .

      I look forward to receiving your answer soon.
      Best regards
      Raiola Giancarlo
      [Date/Time=07-04-2002 - 3:23 PM]    Name:Raiola Giancarlo, [Msgid=278810]

    Swath ships architecture Thesis
      Dear Raiola,

      The International Hydrofoil Society is primarily concerned with hydrofoil craft and to somewhat of a lesser extent the application of hydrofoils to other marine vehicles. As a consequence, you will not find a significant amount of information about Small Waterplane Area Twin Hull (SWATH) vessels on the IHS website.

      A good overview of SWATH vessels is provided in Naval Engineers Journal, Volume 97, Number 2, February 1985. ISSN 0028-1425. Published by the American Society of Naval Engineers, Inc. (ASNE). More details of that issue can be found on the IHS website under the section about magazines related to hydrofoils.

      There is a hybrid between a hydrofoil and a SWATH known as Hydrofoil Supported Small Waterplane Area Single Hull (HYSWAS) and you may find more information about that craft on the website.
      [Date/Time=07-13-2002 - 3:57 AM]    Name:Martin Grimm, [Msgid=281953]

    Info wanted on Hydróptero
      Hi Sonia, there is a French hydrofoil with name of "L'Hydroptere" go to http://perso.wannadoo.terrasse.web/hydroptere800.html (No longer available as of 060130WNW)

      Brush up on your French, as the site is French.
      [Date/Time=09-19-2002 - 5:13 PM]    Name:Vivian Dewey, [Msgid=312049]

    Hydroplane Formula`s?      ViewThread
      I am wondering how do i figure out the lift of a foil and the lift coefficients (what formula's do i use).

      This is for a fourth year mech eng project. Basically iam looking at a V-shaped waterplane and a torpedo shaped one with winglets on the front and back of the torpedo. The boat we are trying to design is about 1m in height, 2m in length and 1m in width and weighs about 1500 lbs and has to hydroplane at 20 knots(min). So if anyone could help me out with advice or formula's i would greatly appreciate it. Thanks
      [Date/Time=09-29-2002 - 9:26 PM]    Name:Kris MacKenzie, [Msgid=316589]

    Hydroplane Formula`s?

    Info Source for Foil Profiles      ViewThread
      I am a mechanical engineering student at the University of Nottingham, England. As part of my course I have been given the task of designing a human-powered hydofoil designed to carry two people. The craft needs to travel at a speed of 5m/s and be small enough to fit on a trailer. I have decided that a two-hull design would be best with a fan-powered propulsion system using simple gears and chains to transmit power. The problem I am having is finding information on foil designs, and in particular, foil profiles with information on how much lift and drag each profile generates with information on how these values are determined. I would be extremely grateful if you could send me any information you have on foil profiles or any links for me to follow up. Also if you have any information on human- powered hydrofoils and how I should aproach my design.

      [Date/Time=10-21-2002 - 6:49 PM]    Name:Ben Jones, [Msgid=326753]

    Info Source for Foil Profiles
      There is very little literature on hydrofoil sections, but all the equations and software available for aeroplane wings works for hydrofoils. One of the standard works is "Fundamentals of Aerodynamics" by John D Anderson. The latest edition is quite expensive, but if you can find a previous edition they are a lot cheaper.

      There are various software applications that can calculate the lift and drag coefficients for any foil section and angle of attack. I have used an application called "Panda" from Desktop Aeronautics Inc for this. I think that these applications use 2-dimension finite element analysis to work out the flow patterns and pressure at each point on the foil.

      The actual lift and drag can be calculated from the coefficients and the liquid density, speed and dimensions, with suitable adjustments for the aspect ratio. All the equations are in Fundamentals of Aerodynamics. They are quite complicated.

      This approach is probably only valid for high aspect ratio wings, and won't model the interaction with any struts. However human powered hydrofoils will certainly have high aspect ratios. Strut to wing interaction is not a big problem. Even Boeing has only recently learned how to model it, so it must have been relatively unimportant.
      [Date/Time=10-22-2002 - 7:53 PM]    Name:Malin Dixon, [Msgid=327252]

    Info Source for Foil Profiles
      The Society of Naval Architects and Marine Engineers (SNAME) has published the technical bulletin Blade and Hydrofoil Section Design. This bulletin includes the Blade and Hydrofoil Section Design Codes with a 29-page Owner's Guide, and a 184 page Technical Report. It updates and complements T&R Bulletin 1-17. The Design Codes and Owner's Guide provide tools for the design and performance evaluation of blade and hydrofoil sections. The programs are provided in both DOS and Mac formats and will run on most personal computers. The Technical Report provides analytical background information and is of interest primarily to those who wish to adapt or enhance the programs. This new publication is identified as Technical and Research Bulletin 1-45. It is being issued as a CD-ROM, and may be ordered by contacting or by calling +1-201-798-4800. It is priced at USD50 (USD25 for SNAME members).
      [Date/Time=10-29-2002 - 7:20 PM]    Name:Barney C Black, [Msgid=330718]

    Ways to Cross the Channel      ViewThread
      I am doing a research project on different ways to get across the English Channel. I was wondering if you have any useful links or information about using hydrofoils.
      [Date/Time=10-31-2002 - 5:43 AM]    Name:Tracy Bickford, [Msgid=331484]

    Ways to Cross the Channel

    Supercavitating Propellers      ViewThread
      I am a student at Naval Architecture and Ocean Engineering Faculty of Istanbul Technical University. I have homework about supercavitating propellers. If you have any text,photos,videos or CD about supercavitating propellers, could you help and post me?
      [Date/Time=11-05-2002 - 8:37 AM]    Name:Yasin Uslu, [Msgid=333656]

    Supercavitating Propellers

    solar hydrofoil
      Thanks for the reference to the Solar Hydrofoils.

      I will add it to our IHS links page. They are very interesting. If you have any more performance details we would welcome your comments.

      Bill White
      [Date/Time=11-23-2002 - 6:47 PM]    Name:Bill White, [Msgid=342528]

    Surf Hydrofoil Project      ViewThread
      hi there, I am studying Surf Science at the university of Plymouth. I am looking into the application of hydrofoil technology to surfboard fin design for my third year project.
      I am going to construct a hydrofoil fin that can lift a surfer at between 8-20 knots.
      I have been researching foil cross sections but am at a bit of a loss as to which one too choose due to the vast amount of sections and data
      presented. My initial thoughts were to use a symmetrical NACA 0012 foil but then thought that something like the NACA 2412 would be more suitable and provide more lift. I also noted that many of the Eppler E8's such as E874 were reccomended for hydrofoil use. How do symmetrical foils compare to non and do you have any recommendations for foil cross sections that I could use.
      Thank you for your time.
      Ben Bryant.
      [Date/Time=02-07-2003 - 1:26 PM]    Name:Ben Bryant, [Msgid=374049]

    Re; Surf Hydrofoil Project
      You might take a look at this section,, since it was specifically designed for sailing hydrofoils.

      The main benefit of a cambered section over a symmetrical section is that camber shifts the section characteristics to a nonzero lift coefficient. Maximum lift is generally increased, and the minimum drag can be centered on the operating lift coefficient instead of zero lift. Of course, this means you also have to estimate what the operating lift coefficient is, and this will come from the foil loading (weight carried per unit area) and the speed.

      The Hydronautics handbook on the AMV CD has an excellent chapter on foil sections and optimizing the foil span and planform.
      [Date/Time=02-08-2003 - 2:15 PM]    Name:Tom Speer, [Msgid=374620]

    Re; Surf Hydrofoil Project
      The AMV CD referred to by Tom Speer is the collection of Advanced Marine Vehicle design documents available on CD-ROM from the International Hydrofoil Society at a cost of USD 5.00, including shipping worldwide. For details, see the IHS website at . Note that IHS is very close to releasing a second AMV-CD with additional documents. The Hydronautics handbook is on the first (original) CD-ROM.
      [Date/Time=02-09-2003 - 7:06 AM]    Name:Barney C. Black, [Msgid=374969]

    Re; Surf Hydrofoil Project
      In my humble experience with playing with hydrofoil wave-riding vehicles, I've found that the most critical problems I've faced are related to stability and control. I've used both symmetrical and asymmetrical airfoil sections, but so far I've not been able to discern any significant difference in speed as I've been too busy with control issues.

      The importance of the foil section also will also depend on your primary design goal. If your primary goal is pure speed (and you will be towed into a wave, as with the Air Chair-based hydrofoil boards under development by Laird Hamilton), then the section choice becomes more significant than if you're interested in traditional surfing (i.e. paddling to catch the wave) and/or in maneuverability.
      [Date/Time=02-20-2003 - 12:13 PM]    Name:Terry Hendricks, [Msgid=381786]

    Re; Re; Surf Hydrofoil Project      ViewThread
      thanks a lot friend, im draving cad plans to my model, your help and experience is apreciate, regards from spain.
      fernando palacio
      [Date/Time=02-26-2003 - 4:44 PM]    Name:fernando palacio edreira, [Msgid=385452]

    Re; Re; Re; Surf Hydrofoil Project
      Please note that there is no need to post identical messages in each forum of the BBS. In the future, please select the one forum most appropriate for your message and post it there one time. Thanks!
      [Date/Time=03-11-2003 - 12:49 PM]    Name:Barney C Black, [Msgid=393772]

    Stability of planing vessels      ViewThread
      I am a student at Plymouth University (UK) and am doing a project on the stability of high speed planing vessels. Any suggestions? I need info! Thanks.
      [Date/Time=03-21-2003 - 7:28 AM]    Name:Nick Farrer, [Msgid=400452]

    Re; Stability of planing vessels
      I don't know your exact interest, but if you're good with the Internet, you'll find it all. My favorite linear theory porpoising papers were by Peter Payne and Milton Martin. Some experimental work was done recently by students at USNA and in Korea. Lateral stability is a little tougher. Blount and a few others have looked at nonlinear effects. A good starting place is the old Peter DuCane book. We've been working on augmenting stability for small planing boats (like ferry ride control systems) here in the US. I can probably help you track down what you need.
      [Date/Time=03-22-2003 - 12:14 PM]    Name:jim hynes, [Msgid=401113]

    HELP ; how to build a hydrofoil boat      ViewThread
      hi i am a student in the 9th grade. my partner and i are doing a project on mini hydrofoil boats for our science class. could you give us a list of materials and stuff to build a small hydrofoil boat, about 10x5 in.
      [Date/Time=03-25-2003 - 8:05 PM]    Name:Jabari Gilkes, [Msgid=403010]

    Plans and parts list for model needed      ViewThread
      I presume you propose to build an operating, radio-controlled model hydrofoil as opposed to a static model that just sits on display. This sounds like a fun project, although there will be some costs associated with the control equipment. To get an overview of different models that other people have done, and also to get the names and email addresses of people who you might want to ask to advise you, please see the following pages on the IHS website:

      For a good example of a motor-powered model hydrofoil boat, see Graham Taylor's website at

      For a good example of a sail-powered hydrofoil boat, see the 750mm sailing yacht model website at:

      After you are successful with your model this year, you may want to build a hydrofoil that you can actually ride in for next years project. There are plans available in back issues of Popular Science and Science and Mechanics. The May 1960 issue of Popular Science has plans for a 4' x 8' wooden boat with wooden foils. The June 1960 provides mounting instructions to add the foils from the prior month's issue to any existing boat up to about 16 feet.

      The Feb 1960 issue of Science and Mechanics has plans for foils made of steel frames and fiberglass foil surfaces. The following issue (Apr 1960) has plan for building a small runabout that you can add the foils to.

      For information on these magazines and suggestions where to find copies of these old issues, see our page at:

      Hopefully that information is of some use to you. Good luck on your project.
      [Date/Time=03-26-2003 - 5:07 PM]    Name:Barney C. Black, [Msgid=403688]

    re; rc sailing hydrofoils
      Barney, he might also check out:
      for pictures ofour F3 the worlds ONlY production sailing hydrofoil multihull. We are also about to introduce the microMOTH a 36" radio controlled MONOHULL foiler.....
      I'm also willing to answer any questions at all. He might also check out: a site that has several articles about foils on RC sailing hydrofoils.
      [Date/Time=03-27-2003 - 8:03 AM]    Name:Doug Lord, [Msgid=404079]

    Les Voiliers a Hydrofoils
      Deleted by request 091101
      [Date/Time=03-29-2003 - 6:31 PM]   

    HYSWAS Senior Design Project
      I am currently working with a team on the design of a working HYSWAS model for a senior design project at Florida Atlantic University (FAU). Our team needs information on hydro coefficients so we can run computer simultions to find out how much hp will be needed to generate enough speed to plane. If you have or would like to share any information that would be great.

      [Date/Time=10-13-2003 - 11:42 AM]    Name:Roger Moore, [Msgid=524345]

    build working model foil for science fair      ViewThread
      I am in 6th grade and I am building a small working model of a hydrofoil craft for the school science fair. what advice do you have on things like what material to use, where i could find a good engine, the simplest design that will work.
      [Date/Time=01-06-2004 - 11:54 PM]    Name:James Cobert, [Msgid=567742]

    build working model foil for science fair
      Hi James,

      This sounds like a very nice project to work on. Do you plan to make the model radio controlled or "free running"?

      I would recommend that you make a model driven by an electric motor rather than a petrol engine. These are more clean and quiet and will start easily. With a fully charged NiCad battery pack, such a model should run for 10 minutes or so if built light and well.

      The hull could be built of thin plywood or balsa wood as these materials are easy to work with. If you use balsawood, make it at least 3mm thick. Be sure to seal it well with paint or varnish to ensure it does not get waterlogged.

      I would recommend building a model based on the full scale Supramar / Rodriquez PT 20 design. The reason for this is that:

      1. The hull is quite a straightforward shape.

      2. The foils are of a surface piercing type, so the model should naturally run well while foilborne without wanting to tip over in any direction.

      3. This design has a single propeller mounted behing an inclined propeller shaft. This means you only need to buy one motor etc and the driveline is straightforward.

      You can get away with a 2 channel radio control system for a hydrofoil model. One channel is for controlling the motor speed (or simply on and off) and the other is for controlling a rudder.

      You can build the foils of hardwood if you are not easily able to work with something stronger like aluminium.

      There are several photos of the PT 20 in our photo gallery so you can get an idea of how that hydrofoil looks. There are also a variety of photos of hydrofoil models in the photo gallery.

      Also, plans to build a PT 20 model were once distributed by a company in Europe. That design was intended to be propelled by a petrol engine but could be converted to electric power instead. If you look through the archive of old posted messages on this website there are more discussions of radio controlled hydrofoil model building including more details of the above plans.

      If you let us know how big you would like to make the model and how much time and money you are able to spend on this model, then possibly we can give more advice. Have you built any radio controlled boat or aircraft models before or is this all new to you?

      Hope this helps in the meantime.
      [Date/Time=01-07-2004 - 8:19 AM]    Name:Martin Grimm, [Msgid=567827]

    build working model foil for science fair

      I just had an afterthought that you can also look at the articles on building hydrofoil models which are regularly featured in the free on-line magazine "Classic Fast Ferries" produced by Tim Timoleon. The address is:

      The most recent issue includes two different models of the PT 50 design, one of them was once sold as a kit. The PT 50 was a larger twin engined design based on the PT 20 which I reccommended you could build.
      [Date/Time=01-07-2004 - 8:35 AM]    Name:Martin Grimm, [Msgid=567836]

    build working model foil for science fair
      As a science fair project, I recommend you make a long-ish tank with some plywood and 2x6's, lined with a plastic sheet. At the end, put a pulley with a string that goes from the bow of your model to a weight. You may need to have a vertical frame at the end, too, with a second pulley so the string goes from the model to the first pulley, up to the second, and down to the weight. This will let the weight drop far enough to pull the boat down the whole length of the tank.

      With this system, you can release the weight and time how long it takes to pull the model down the tank. The weight times the height it drops provides a known amount of energy and thrust on the model. So the faster the model goes, the less drag it has.

      Make a series of runs with different amounts of weight pulling the models, recording the time required at each weight. If you use a water bottle as a weight, you'll have to carefully measure the weight or the amount of water in the container each time. If you use solid weights, you can measure them once and reuse them. Plot the drag (amount of weight used to pull the model) versus speed (distance traveled divided by the time) to see that relationship. Then repeat the whole series of tests with a different model. With this simple tow tank, you can compare boats with and without hydrofoils and different kinds of hydrofoils.

      Alexander Graham Bell did experiments like this, pulling his hydrofoil models behind boats. Go to and select "Beinn Bhreah Recorder", Volume 12, page 366b and then click through tne next several pages.

      The report that follows the pictures gives an interesting view to how research is really done. Compare the idea at the end with the report by Bell's chief engineer, Baldwin, in Volume 23, page 49 of Bell's HD-4 hydrofoil. There you'll see the final result that came from the idea in the sketch.

      Other Bell hydrofoil model experiments are in:
      Vol. 10 pg. 347 - 365
      Vol. 12 pg. 363a - 366b
      Vol. 13 pg. 32 - 33
      Vol. 9 pg. 75a - 77b

      Bell also tested a water ski-like model (Vol 14 pg 85a - 86c, Vol 14, pg 228a - 229b; Vol 14, pg 398a - 401b) that would be a good model for you to test for comparison with a hydrofol.

      [Date/Time=01-11-2004 - 11:05 PM]    Name:Tom Speer, [Msgid=570036]

    build working model foil for science fair
      Thanks very much for your suggestions, which were really helpful. If you don't mind, I still have some questions about how go ahead with the experiment that you describe.

      1. The Boat/Foil:
      Do you have any ideas about a very simple model boat to which I can attach the foils? I would prefer to buy a boat or make a model from a kit since that would be easiest. I tried the hobby shope where I live but they didn't have any. I have seen some models on the internet for small wooden boats about 8" long and 3 " wide. Would it be possible to attach hydrolfoils to a boat like this one? what shape boat should I look for? Or, do you have suggestions about very simple plans for boats/foils that I could build? Also, materials for constructing the hydrofoils

      2. The Tank:
      I liked your suggestions about the plywood and plastic sheet. What dimensions for the tank would work in terms of length? How deep should it be? would the 2x6 pieces be for the sides or what else might work. For the frame, it sounds like I should attach a vertical piece as the end as the anchor for teh second pulley. If you have any more specific ideas here, that would be great.

      Thanks so much for all of your help -- I will let you know how things turn out.

      [Date/Time=01-13-2004 - 11:57 PM]    Name:James Cobert, [Msgid=571144]

    build working model foil for science fair
      You might try building a simple catamaran from model rocket tubes and balsa nose cones. Add a skeg to the stern of each hull to make it track straight. This has the advantage of being light and stable.

      You could make the hydrofoils out of balsa, or spruce (stronger than balsa), or sheet metal. Or a combination of all 3. You could even cut strips out of a Coke can and glue them to balsa struts with epoxy. You'll find the aluminum can to be somewhat brittle, but you can cut it with a pair of scissors. You may find plastic extrusions that could be modified into hydrofoils, too.

      Go to a hobby shop and use your imagination - lots of model airplane or even model railroad stuff could come in handy. If there's a model airplane club that meets near you, I bet you can find lots of advice and help there, too.

      Ideally the tank should be as long as possible, but is limited by practical considerations. One is the height you can drop the weight. Most ceilings are 8 ft high, so the tank would be less than 8 ft long. You could double the distance the weight will pull the model by putting a pulley on the weight, anchoring one end of the cable to the top of the frame, and using the other end to pull the model. This will mean the tension on the cable is half the driving weight, but it will pull it twice as far.

      So one way to make the tank might be to take a piece of 4'x8' plywood (1/2" thick, maybe?), rip it in half to form two 2'x8' pieces, and hinge them end-to-end. That would make a 16' tank that you could fold into 8' for transport when you take the plastic off. With the 2x4 or 2x6 walls, the tank would have to fold bottom-to-bottom, of course, with the walls on the outside. The tank would sit flat on a couple of folding tables.

      I'll leave it to you to figure out how much weight would be on each table, based on the volume of water in your tank, and decide if that's too much for the tables or not. The tank can be drained with a garden hose used as a siphon. Or you can get a waterbed kit for filling and emptying it. These often have a venturi pump that can suck the water out faster.

      [Date/Time=01-25-2004 - 8:47 PM]    Name:Tom Speer, [Msgid=578107]

    Student project      ViewThread

      I am currently studying for my degree in marine technolgy at the university of plymouth.  For part of this degree I have to do an honours project which involves looking into an aspect of marine design.  I have chosen to look into how t-foils effect the performance of small 14ft racing sailboats, and in particular how they help stop the pitching of the boat.

      Hence I would be very gratefull if you could send me any information on this subject, and in particular any calculations and foil tests that you have done.

      Thank you for your time.

      Matt Chapman
      [Date/Time=02-26-2004 - 11:12 PM]    Name:Matt Chapman, [Msgid=604277]

    How foils work?      ViewThread
      I am a student in year 10 currently doing a project on hydrofoils and building a model. I am having lots of trouble finding any research on how a hydrofoil works and how it creates lift. I know it resmbles an aeroplane wing but i am having trouble explaning how the lift is created. Iff you could help me out by maybe explaining or providing me with some information it would be greatly appreciated. My assignment is due in 2 and a bit weeks so any help will be greatly appreciated. Thanks, Chris
      [Date/Time=02-26-2004 - 11:18 PM]    Name:Chris Phillips, [Msgid=604282]

    Re; Student project
      Please check our IHS web site section on sources and discussions on the subject. You should find what you need there.

      If you need more detail, try our CDs which have lots of technical papers on the subject.

      Bill White
      [Date/Time=02-27-2004 - 11:00 AM]    Name:Bill White, [Msgid=604482]

    Science Fair project on hydrofoil boats      ViewThread
      My son is doing a science fair project on hydrofoil boats. We are looking for a video and model we can purchase. We thought you could tells us where we could purchase them.

      Thank you Janet Harrison
      [Date/Time=02-28-2004 - 6:51 PM]    Name: Janet Harrison, [Msgid=605177]

    Science Fair project on hydrofoil boats
      Hello Janet,

      Unfortunately there are few hydrofoil model kits available these days as they are all out of production. One option to track such a model down would be to keep a look out on Ebay online auction site for one to be offered. This may not be a practical proposition for you.

      For a videos on hydrofoils, follow the link "Books, Videos and Popular & Trade Magazines" from the main age of the IHS website and see what is listed. One video which has a good overview of hydrofoils is listed as follows:

      [13 Oct 03] The new Discovery Canada video Hydrofoils: Flying on Water is available in VHS format for $29.95, including shipping and handling within the U.S. and Canada. IHS assisted in compiling historical photos and video clips for this production. More details and a description of the video are on the internet at . To purchase a copy of the VHS tape, send a cheque or money order to: Lucy Decoutere; 1657 Barrington St., Suite 138; Halifax, Nova Scotia; Canada B3J 2A1; Tel: 902.446.3414; Email:

      [Date/Time=03-06-2004 - 7:47 AM]    Name:Martin Grimm, [Msgid=608656]

    Lift off Speed?      ViewThread
      I am building one man hydrofoil boat, and I am planning to put hydrofoils
      on a rowing boat! I am wondering what speed I need to get the boat out of
      the water. Doe sit depend on the size of the Hydrofoil. I would like to
      get the boat out of the water at the slowest possible speed, I hope this
      is possible.
      Many Thanks
      Philip Rage
      [Date/Time=07-12-2004 - 8:48 PM]    Name:Philip Rage, [Msgid=678447]

    model rocket boat      ViewThread
      Im currently working on a model rocket boat project for an internship. we are given several pieces of aluminum, an estes d-12 model rocket engine, and a few requirements like it cant get airborn. the object is to make it go the farthest. I was interested in puting a hydrofoil on it to reduce drag from the water and increase distance. I dont really have any experience with hydrofoils though. Is the idea feasable with such a small boat? will it work with a rocket engine? will it be stable with no remote control? Anything will help, thanks
      [Date/Time=07-14-2004 - 1:22 AM]    Name:Alan, [Msgid=679221]

    Re; model rocket boat
      The difficutly you have, is testing the boat prior to an actual rocket powered run. It took two non radio controlled "crashes" for me to get a rocket car to run straight. And these runs, it was radio controlled. Not that you could steer it during a run, but it did give us some measure of steering during a run. See this link.

      What should be noted, is that from the start, the nose was weighted with at least 150- 200 grams of lead to keep the nose down. The roll over you see in the first run is due to too large a drag chute.

      The point I try to make here, is that you will need to run the boat several times to get the boat trimmed. Especially on hydrofoils.
      In a hull born boat, The rocket at a slight down angle and a skeg at the back of the transom would probably be enough to keep the nose down and fairly level. Once you lift the boat out of the water on a foil, the dynamic will change completly. If you keep the foils low, and can do some testing using an electric motor, you probably have a good chance of succeeding.
      Safety first always. Once a rocket is lit it won't stop.

      Aimee Eng
      [Date/Time=07-17-2004 - 12:26 AM]    Name:Aimee Eng, [Msgid=680936]

    Re; model rocket boat
      I have contributed the report to the model R/C hydrofoil. It got interested in your model rocket hydrofoil. Would you teach [ you ] me the model rocket hydrofoil under plan in detail? Then, I think that I can provide you with the idea of a useful hydrofoil. It is the size of * rocket engine, and a weight * injection thrust, * injection time and the above item that I want to know. I wait for a reply. Please see the BBS contribution report of my model R/C hydrofoil.
      [Date/Time=07-17-2004 - 12:44 AM]    Name:yoichi takahashi, [Msgid=680941]

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