International Hydrofoil Society Photo Gallery


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WILLIWAW Pioneering hydrofoil yacht designed, built, and sailed extensively throughout the Pacific Ocean by David A. Keiper of DAK Hydrofoils.

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TECHNIQUES AVANCEES French Racing Catamaran





Mike McGarry (Canadian and US Champion) flying his Rave on a reach in fairly light air.
A starting line shot of Rave Regatta at first race. Hard on the wind and hullborne for starting.
Hobie TrifoilerMore photos at
Dave Carlson’s Hobie 18 with foil kit attached.

Information from Dave Carlson




VOLADOR II was a canard type hydrofoil, having ladder main foils with cantilever low end. It had 14 m2 sails. The hydrofoil was designed and built by Fulgencio García and Adolfo Avilés in Spain.



EIFO hydrofoil trimaran
Dr. Sam Bradfield’s trimaran that he converted into a hydrofoil by inserting Rave style incidence control mechanisms into the daggerboard wells.
His website

Baranski Hydrofoils
Article by Michael Baranski

Dactyloptera, build by Alexandr Jegorov.
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(Several More images)
Miller hydrofoil windsurfer. Description is at
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This is an International Moth class dinghy fitted with Tee foils. It has a trailing sensor arm to control the main foil and ride height. Total fully rigged weight is 30kg. Designed and built by Fastacraft in Australia. For more information see and also the class website at
Photos from John Ilett
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(Several more images)
Rohan Veal sailing at the Moth world championships in France using a Fastacraft hydrofoils built by John Ilett in Western Australia.
He ended up 3rd overall and created a lot of interest about the foils on the international moth. He expects to see a lot more people using them in the future.
Rohan’s website is at and more information about the class is in the box above.
Modified Bethwaite Mk II
More images and more information.
Broomstick – Hydrofoil Trimaran by Doug Halsey
Original images and more information.Current Images and more information Nov 2007Download Current Images and more information (wnw071111) 

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The International Hydrofoil Society (IHS) Hydrofoil Message: Chats, Info Sharing, Networking

The International Hydrofoil Society (IHS) Hydrofoil Correspondance Archives


General: IHS Administration Design of Foils: Foil-Struts-Controls-Performance Design of Vessels: Hull-Machinery-Costs-Performance/Ops History of Hydrofoils: People-Vessels-Operations Hydrofoils: Commercial Hydrofoils: Military
Hydrofoils: Models Hydrofoils: Pleasure Hydrofoils: Sailboats R/D: Student Projects/Thesis etc. Sources, Buy/Sell: Brokers-Builders-Designers-Operators Miscellaneous:Hybrids-Other High Performance Vessels-etc.

Updated last August 20, 2006

Hydrofoils: Sailboats

Hydrofoils: Sailboats      Scroll To Top Top


Archived Messages


“1”,”946256″,”9″,”Re; Foilboard Video||946256″,”OK, all you technical types out there – take a look at this video and then try to explain how it’s balanced about each axis!

Furthermore, if the foiler had been more balanced, he could have focused on speed and the non-foiler might not have overtaken him at the end of the video.

I’m guessing the Miller foil sailboard ( ) has better pitching stability.”,”2005-12-12″,”Mac Stevens”,”nopswd”,” “,””,”945786″

“2”,”946245″,”9″,”Re; Foilboard Video||946245″,”OK, all you technical types out there – take a look at this video and then try to explain how it’s balanced about each axis! Ok, I’ll try:

I challenge your premise that it is balanced about each axis. The board appeared quite unbalanced.

I think it is balanced the same way a unicycle or an ordinary sailboard is balanced, i.e., the operator’s control of weight and other forces.

The rear hydrofoil probably adds some pitching stability.”,”2005-12-12″,”Mac Stevens”,”nopswd”,” “,””,”945786″

“3”,”946241″,”9″,”Re; Foilboard Video||946241″,”OK, all you technical types out there – take a look at this video and then try to explain how it’s balanced about each axis! Ok, I’ll try:

I challenge your premise that it is balanced about each axis. The board appeared quite unbalanced.

I think it is balanced the same way a unicycle or an ordinary sailboard is balanced, i.e., the operator’s control of weight and other forces.

The rear hydrofoil probably adds some pitching stability.”,”2005-12-12″,”Mac Stevens”,”nopswd”,” “,””,”945786″

“4”,”945786″,”9″,”Foilboard Video||945786″,”OK, all you technical types out there – take a look at this video and then try to explain how it’s balanced about each axis!”,”2005-12-10″,”Tom Speer”,”nopswd”,” “,” “,”9”

“5”,”873505″,”9″,”Re; Hydrofoil Voyager David Keiper Book||873505″,”I have just listed a copy of David A. Keiper’s book Hydrofoil Voyager on eBay. The item number to search for is 4567171188. This is a 10-day listing. This item is out of print and scarce. The book is (mostly) about design, construction, and sailing in the Pacific in the first hydrofoil sailing yacht WILLIWAW. See the listing for more details. There is a review of this book at: There is info about Dave Keiper at: There is a short video clip of WILLIWAW in action at (this is an 11 meg file, so don’t dare go there if you have a slow internet connection!) Questions about this book may be submitted via the listing on the eBay website.
“,”2005-08-08″,”Barney C Black”,”poopdeck”,” “,””,”9″

“6”,”862912″,”9″,”Hydrofoil Voyager David Keiper Book||862912″,”I have just listed a copy of David A. Keiper’s book Hydrofoil Voyager on eBay. The item number to search for is 4563256226. This is a 10-day listing. This item is out of print and scarce. The book is (mostly) about design, construction, and sailing in the Pacific in the first hydrofoil sailing yacht WILLIWAW. See the listing for more details. There is a short video clip of WILLIWAW in action at (this is an 11 meg file, so don’t dare go there if you have a slow internet connection!)”,”2005-07-18″,”Barney C Black”,”poopdeck”,” “,” “,”0”

“7”,”851283″,”9″,”Re; Re; Surface piercing hydrofo||851283″,”Jake,

The foiler moths that I have seen don’t have fences fitted and seem to be able to get away without them. In the first instance, in your position, I wouldn’t bother to fit fences and just test the board to see how it goes. After experimenting, if you have the feeling that air is being drawn down on the low pressure face, then you can always retrofit a fence or two later. Any fence will normally add drag, and that is the last thing you need if you are trying to speed sail. “,”2005-06-26″,”Martin Grimm”,”nopswd”,” “,””,”0″

“8”,”830684″,”9″,”Rave Hydrofoil for Sale||830684″,”WindRider RAVE Hydrofoil Trimaran Sailboat, 1999, Main and Jib, yellow hulls, custom galvanized trailer. Dealer display boat. $4000

Bob Rundus Sailboats
36 East Green Street
Champaign, IL 61820
Phone 217-359-3000
“,”2005-05-18″,”Robert Rundus”,”nopswd”,” “,””,”0″

“9”,”821336″,”9″,”Re; Re; Surface piercing hydrofo||821336″,”Thanks Tom,
I have just re-read my posting and I have been somewhat confusing. I am not looking at bi-directional foils. I am wishing to build a pair of asymetric windsurfer fins suitable for surface piercing usage, as the fin will be fitted behind or to the side of the board, not sticking out of the bottom of it, and may be canted to provide some lift. As I have fitted the device to a speed board and intend to take it to Weymouth speed week this year, low drag and no ventillation at high speeds are important factors. I have also conceived a system that enables the two separate fins, one port , one starboard profiled to be swapped while sailing. I just need to get the test rig working on one tack so that the optimum fin position, cant, rake, attack angle etc. can be discovered.
Could I just use one of the profiles you recommend for foiler moth lift foils and fit a couple of fences?
Rich Miller, by using a long symetrical root foil with fence, ended up with his asymetric foils submerged all the time, so the demands on his foils were slightly different to mine. “,”2005-04-30″,”Jake Frith”,”nopswd”,” “,””,”0″

“10”,”821326″,”9″,”Re; Re; Surface piercing hydrofoil||821326″,”I don’t think ogival sections are a great idea. The sharp leading edge leads to separation unless the angle of attack is in a narrow range of ideal angles of attack. When separation occurs, you have all the ideal conditions for ventilation. So everything can be fine, and then suddenly change dramatically with just a small difference in loading.

It’s possible to design bi-directional sections that have rounded edges instead of sharp ones. With attached flow at the leading edge, you can maintain a good run of laminar flow, while still controlling the location and extent of the laminar separation bubble. And separation begins at the trailing edge, where it can progress smoothly and predictably as you load the foil.

For an example of such bi-directional sections, see These are predicted to have comparable performance to conventional NACA sections, but no experimental data are available to confirm this yet.”,”2005-04-30″,”Tom Speer”,”nopswd”,” “,””,”0″

“11”,”819881″,”9″,”Corection to address||819881″,”Hi Jake,

Here’s a quick correction to the web site given previously. It is: and the tread you are looking for is “foiler design”. You will probably be required to register, but you should find the site to be useful.

If you reply and need a response, use this temporary address: “,”2005-04-28″,”Ray Vellinga”,”nopswd”,” “,””,”0″

“12”,”819877″,”9″,”Re; Surface piercing hydrofoil||819877″,”Jake,

If you are not already reading, you should try it. There you will find a running dialog about designing hydrofoil sailing moths.

If you design a sailing board that reverses direction, look at the Ogival sections. They are symetrical fore and aft, ie, they have sharp leading edges coming and going. They are a segment of a circle on top with a flat underside.

Hope this helps.

Ray Vellinga”,”2005-04-28″,”Ray Vellinga”,”nopswd”,” “,””,”0″

“13”,”819373″,”9″,”Re; Surface piercing hydrofoil||819373″,”You raise quite a few thought provoking questions in your posting. Hopefully one of the design-oriented people in IHS will answer you. Meanwhile you might want to take a look at Rich Miller’s successful design, if you have not already seen it. Check these two pages:

I doubt that Rich follows the IHS BBS, so if you want to talk to him, you could certainly give him a call or send him an email. The last contact info I have for him is: Rich Miller (; 640 Colusa Avenue; Berkeley CA 94707 USA; phone: 510-525-8006. I am not sure if all that is still good.”,”2005-04-27″,”Barney C Black”,”nopswd”,” “,” “,”0”

“14”,”819015″,”9″,”Surface piercing hydrofoil||819015″,”I would be enormously grateful for any advice IHS membes can give on the following:
I am nearing completion of a sailboard based test rig which I intend to use to attempt to achieve a semi hydrofoiling single tack sailboard. In short, the system uses a conventional board, truncated aft of the back strap with finbox removed and filled in flat. There is a mechanism that allows the fin to be adjusted in pitch, cant, angle of attack, depth, and -within the constraints of the position of the board and the sailor’s back foot- position. (In other words infinitely adjustable)
I propose to carry out the following test schedule:

1) Fix a conventional symetrical fin centrally as far forward as the back of the board will allow, ie., so it is in the same position as it would have been slid right to the back of the finbox, except it will no longer have the endplate effect of the board. The task here will be just to get the thing sailing. First barage of questions… Will a conventional fin just spin out due to the loss of the endplate effect allowing air to be sucked down? If I wish to fit fences to the fin, how big should they be, should they entirely surround the chord or just be around the leading edge? Should the fences be angled up or down, if so by how much? When I travel at high speed in choppy water on a standard board and the tail of the board frequently leaves the water I don’t immeadiately spin out, so would I even need to modify the fin at all?

Part ii)Fit asymetric foil/s (single tack use obviously) so that the fin will attempt to provide lift, rather than just lateral resistance, and start playing with angles of attack and canting the fin (tip to windward) to provide a more accurate counter to the forces from the sailor’s feet and the mastfoot. I have been looking at the horizontal lift foils that Moths are using, but am not sure if they will work in the context of surface pircing and at the higher speeds. (anything over 50 knots will do:) Once again, will it need fences?
Essentially my problem is that I have spent far too much time actually windsurfing etc. to learn how to design my own bespoke range of foils for this craft. I am capable however of drawing a series of chords from foil coordinates and building a simple foil.
Does anybody have a good idea what foil already designed (and at what scale of chord) might work for these purposes (both the symetrical and asymetrical), and where I might find the coordinates. For ease of fabrication I would like to try a straight untapered foil, perhaps just with a bit of finishing at the business ends that could also be end for ended for the different tacks on the asymetric foil.
Any other comments on whether this has been done before etc. most welcome.
Final inventor’s rant… I believe that the recent regaining of the outright speed sailing record has largely been due to Finian Maynard’s adoption of a single sided rig. After all Yellow Pages’ foils only allowed it to sail on one tack. Why, when water is some 800 times denser than air and fairly primitively rigged ice yachts have bettered 100mph, is the windsurfing world wasting time developing rigs while still sailing on fins that are hugely compromised by having to work on both tacks?
Secondly, Think why a windsurfer has a fin mounted in the middle sticking out of the bottom of the board at the back. I think it might be lazy thinking – the evolution from surfboards which do not have to cater for the same loads, and ease of manufacture. There are two seperate forces delivered by a windsurfer: planing lift of the board and lateral lift of the fin. by sticking the fin out of the board, surely you are introducung all sorts of strange immeasureable vortices at its base. The stuff I am doing at the moment is attempting to divorce as much as possible the two different goals of board and fin. It may of course not work…
Any ideas, help gratefully received here or on”,”2005-04-26″,”Jake Frith”,”nopswd”,” “,””,”0″

“15”,”817494″,”9″,”New Book on Hydrofoil Sailboat MONITOR||817494″,”The auction is now closed. However, the book can still be purchased direct from the author. The closed eBay listing can be viewed for 90 days to get details about the book and some copies of the illustrations. Just used the advanced search function on the ebay site to search for the item number among the completed auctions.”,”2005-04-23″,”Barney C Black”,”poopdeck”,” “,” “,”0”

“16”,”814200″,”9″,”New Book on Hydrofoil Sailboat MONITOR||814200″,”There is a new book for sale on eBay about the hydrofoil sailboat MONITOR developed in the mid-1950s by Baker Manufacturing Co with US Navy backing. Go to and search for item # 4542861342. The listing expires in five days.

The 61 page soft cover book includes 19 drawings and sketches of various elements of the MONITOR design covering the foils, hull, sail and control arrangements. Also contained in the book are 25 photos of MONITOR and other Baker hydrofoil craft. The back cover features a screen shot from a simulation by Hanno Smits. This book is undoubtedly the most definitive single source of information describing the MONITOR design.

MONITOR Principal Characteristics:

Sail area: 230 square feet
Length of hull: 26 feet
Overall width: 21 feet
Weight 1014 lbs plus operator(s)
Wind velocity required to fly: approx 13 knots
Automatic trim regulation with varying thrust
Steering by rotation of rear foil
Foil incidence angles adjustable in flight
Rolling moment partially compensated by differential adjustment of foil angles

This book will be of interest to designers and engineers who want to know the details of MONITOR’s design and construction. It is also of interest to hydrofoil historians and model makers. People intrigued by David Keiper’s hydrofoil yacht WILLIWAW and hydrofoil sailboat STORMY PETREL may also be interested in this book about an earlier sailing hydrofoil craft.

“,”2005-04-16″,”Barney C Black”,”poopdeck”,” “,” “,”0”

“17”,”789894″,”9″,”Telestar foil conversion||789894″,”Michael

Go to our primary web site at

Then go to our Pico search at the bottom of the page and enter

Sailing Foils or ladder foils

You will find tons of information addressing your conversion.

It has been a long time since I saw a working Telestar. Good Luck

Bill White
Web master”,”2005-03-02″,”William White”,”nopswd”,” “,””,”0″

“18”,”782452″,”9″,”Telstar 28||782452″,”Intersted in building a ledder hydrofoil on my Telstar 28 (simmiler to dak hydrofoil).
looking for information/blueprints/etc that can help me with this.
“,”2005-02-16″,”Micael”,”nopswd”,” “,””,”0″

“19”,”764795″,”9″,”Re: Bruce’s Foil||764795″,”The best information is by Edmond Bruce himself – “Design for Fast Sailing,” The Amateur Yacht Research Society, 1976. I think there’s also some information on Bruce foils in the AYRS book, “Sailing Hydrofoils.”

(Some background: the Bruce foil is like a daggerboard or centerboard placed on an outrigger instead of on the centerline of the boat. The foil is canted to provide a stabilizing vertical force as well as a horizontal force to counter the side force from the rig. This greatly reduces the heeling of the boat, using the hydrodynamic moment from the foil for lateral stability instead of the hydrostatic moments from hull form stability or keel ballast.)

Bruce typically canted the foils at 45 degrees from the vertical (tip inward). The outrigger beams were sized such that the center of laeral resistance of the foils was located the same distance from the centerline as the height of the center of effort of the sail rig. Both low aspect ratio foils and moderate aspect ratio foils were used. His small scale tank tests showed an aspect ratio of 1 gave him the best performance, although he only tested aspect ratios of 3 or less and at low Reynolds numbers. I believe in later publications he used a planform with a circular arc (ogival) leading edge and straight trailing edge.

In his moderate aspect ratio sailing experiments, he mounted the foil on a small outrigger float with a pivot so that it could be raked aft like a centerboard when the foil was to windward. One needs to have the center of lateral resistance aft with the foil to windward and forward with the foil to leeward to get the same directional balance as a centerboard, because the force from the sail is inclined forward.

As for sizing the foil, I’d be inclined to use 40% more area than you’d use for a conventional foil. I’d also go with a high aspect foil rather than the low aspect ratio that proved best in his tow tank tests. Naturally, a symmetrical section is required because the foil has to operate on both tacks.”,”2005-01-15″,”Tom Speer”,”nopswd”,” “,””,”0″

“20”,”762800″,”9″,”Bruce’s Foil||762800″,”Can anyone supply design criteria for an Edmond Bruce foil?”,”2005-01-12″,”B.Rowe”,”nopswd”,” “,””,”0″

“21”,”738445″,”9″,””Monitor Hydrofoil Sailboat“||738445”,”The book “Monitor Hydrofoil Sailboat Design in Review” is now available. The cost is $25.00 plus $5.00 S&H in the US. S&H for Europe is $10.00 USD and for Australia is $12.00 USD. Please include mailing address.
Orders are to be made thru: Neil C. Lien
424 Meadow Lane
Evansville, WI 53536
“e”mail address:
phone 608-882-5551″,”2004-11-15″,”Neil C. Lien”,”nopswd”,” “,””,”0″

“22”,”732074″,”9″,”Trimaran stability||732074″,”I have a Sea Pearl trimaran and am looking for ways to reduce weight. The boat is 21′ with a beam of 14′. The center hull is 5’6″. Would it be feasible to replace the amas with foils to provide lift? They would either skim the surface or be out of the water in light air, but would gradually submerge as the wind picked up, eventually balancing the design force from the sails. The center hull will provide adequate form stability at rest. Thank you.”,”2004-11-02″,”Bruce Rowe”,”nopswd”,” “,””,”0″

“23”,”722690″,”9″,”Re: hydro foils for kiteboard||722690″,”Hi Rich,

I am French so excuse me if my English is poor.

Congratulations for your kitesurf performance. I am not sure that the solution to go faster is an hydrofoils system.
The limit speed could be caused by the very strong drift force due to the kite.
If you want to experiment hydrofoils, you have to study very seriously these systems ( I think there is not a good “ready to use” system which can be fitted on a kitesurf )

You can use composite material (fibreglass, carbon fibre, epoxies resin) to make hydrofoils (not only metal). You can buy, for example, long sailboard fins (about 50 cm) to begin tests (symmetrical profiles, but it can be used)

Good luck and contact me if you want more information.

Gerard Delerm
“,”2004-10-13″,”Gerard Delerm”,”nopswd”,” “,””,”0″

“24”,”721718″,”9″,”hydro foils for kiteboard||721718″,”I have recently competed in Weymouth speed week on a kitesurf kite and standard board and have posted a speed of 30.97 knots.
I wish to increase the speed and the only thing I believe is stopping me is the boards resistance. I wish to try out hydrfoils on my board that will lift the board approx 5-10 cm off the surface of the water. I have thoght about using hydrfoils off model boats.
The hydrofoils will have to be made of metal I think. Has anyone got any suggestions of where I could get such things from or made?
The board I am using is 130cm long and 37cm wide.
I look forward to your suggestions
Richard Gowers
Uk”,”2004-10-11″,”Rich Gowers”,”nopswd”,” “,””,”0″

“25”,”715101″,”9″,”T Foils||715101″,”Please send me a sample 2004 newsletter and information about joining your org. I am a small sailboat builder in the USA and I want to learn about T-foils for daggerboards and rudders. To date I know almost nothing, could you recommend a book or books that could teach me about foils. I build a moth boat and the Europe Dinghy (which is a moth boat but has a more advanced sail) Anything you can do to help me get started will be greatly appreciated.
Thank You,
Charles Graves
Graves Little Boatyard
1675 Riahardson Road
Merritt Island, Florida
USA 32952”,”2004-09-27″,”Chas @ Graves Little Boatyard”,”nopswd”,” “,””,”0″

“26”,”699955″,”9″,”catlift foils||699955″,”I don’t know about the catlift foils. I do have some of the Dak foil sections, if you need to see a section profile. Sorry, no plans or complete kits, although they do turn up rarely the internet.”,”2004-08-26″,”Scott Smith”,”nopswd”,” “,””,”0″

“27”,”692423″,”9″,”Re; Catlift information?||692423″,”Gordon,
I can’t say I have heard about the “Catlift” foils but certainly many years ago David A. Keiper (DAK Hydrofoils) developed a “Dak-foil” conversion kit for Hobie 16 catamarans. A photo of a Hobie fitted with such foils appears in the 1978 issue of Jane’s Surface Skimmers. You can find other information related to David’s work on our website. Unfortunately, he passed away a number of years ago.”,”2004-08-10″,”Martin Grimm”,”nopswd”,” “,””,”0″

“28”,”692419″,”9″,”,Re; Catlift information?||692419″,”Gordon”,”2004-08-10″,”Martin Grimm”,”nopswd”,” “,””,”0″

“29”,”685487″,”9″,”Catlift information?||685487″,”Hi,

Does anyone have any information on a device called a Catlift. It can supposedly be attached to a Hobie Cat or Top Cat and lift if up using a small hydrofoil.

Any information you may be able to provide would be appreciated.

Thank you,

Gordon Swift”,”2004-07-27″,”Gordon Swift”,”nopswd”,” “,””,”0″


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