|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 Top
[17 Feb 99] I received some further information from Aldis Eglais in Latvia (Lettland), the designer of the Catri 26R MicroFoiler. At the moment I'm still in the planning phase of my project but I intend to build the boat this summer here in Switzerland. Aldis is offering the plans for a very good price (US$ 1,300), and I'm very close to ordering them. I'm waiting now for his study plans. I will keep you informed. His E-Mail: firstname.lastname@example.org. -- Phil Schlund (email@example.com)
[17 Feb 99] There is a short article about the Catri 26 Trimaran on page 48 of Multihulls Magazine Mar/April 1998 edition. The address given is Aldis Eglajs; Maskavas 291/5-26; Riga LV-1063, Latvia; Tel/fax : +371 7258427. -editor
[17 Feb 99] In Winter 1997-98 I did a project for a Dutch company called PJPC Multihulls. They wanted to build the Catri 26 for the European market to sell for about US$50,000. There were complete plans for making the (eastern European) ship suitable ( more comfortable) for the rest of Europe, which was part of my study (I was asked to design a mechanical device to lift the two swords). Unfortunately the Dutch company stopped their activities due to health problems of the owner, so I am at the moment looking for other tri-builders who could use my design. If you want to know more, contact me. -- Maarten de Jong (firstname.lastname@example.org)
[21 Feb 99] We are working out two types of Catri Foilers -- trailerable cabin boat range (22' 26' 30') and offshore cruising & racing range (35' 39' 45'). After very successful prototype tests in the Netherlands there are two shipyards in Latvia started with 22' and 26' and one in San Francisco starting with 26'. The first boats will be delivered this Summer. The 30' will be started in March for delivery beginning 2000. There are some homebuilders in Australia and elsewhere. You can find our presentation and description of Catri 22, 26R, 30 as well as the draft price list in the attachment. -- Aldis Eglajs, Catri Marine (email@example.com)
[Date/Time=03-21-2002 - 10:52 PM] Name:firstname.lastname@example.org [Msgid=236662]
[13 Jan 02] This looks exactly like the site I need. I want to have a crack at the wind-powered water speed record, and I reckon the only way we're going to get the thing fast enough is up on a foil. The only problem is I have absolutely no idea. If anyone has info. it really would be appreciated (formulas/heights anything to help me build the hull) -- Ian Montgomery (email@example.com)
[13 Jan 02] The world sailing speed record was once held by a hydrofoil - Greg Ketterman's LONGSHOT. This boat has since been adapted for production as the Hobie TRIFOILER . A used TRIFOILER would be a good way to get experience in high speed sailing. In my opinion, the world speed record has risen out of the reach of subcavitating hydrofoils. The current record holder used planing hulls, which you can think of as fully ventilated supercavitating foils operating at the surface, which is where a supercavitating foil is most efficient. Cavitation proved to be a barrier to Ketterman's pushing his hydrofoil to today's speeds, and I doubt if there's much you can do with section shaping to raise the cavitation speed much higher. Designing a supercavitating hydrofoil system that had a lift/drag ratio adequate for a sailing craft is just feasible, but requires very sophisticated hydrodynamics design. Hydronautics' experience with their supercavitating helicopter-towed sled demonstrated drag reductions on the order of 40% -60% just by doing a more sophisticated type of analysis of the spanwise hydrodynamics of their design. You'd have to do the same for a sailing hydrofoil. Something like the Windjet LANDYACHT adapted for the water might be a starting point for the hull and rig design. -- Tom Speer (firstname.lastname@example.org); website: http://www.tspeer.com
[5 Mar 01] Is there any website on a leeward-foil assisted faaast monohull dinghie, say an IC, Contender or 505 with a Bruce on a 3m lever ? -- Claus-C. Plaass - Pickert 10 - 24143 Kiel - Germany - email (email@example.com), ph +49-431-36 800
[5 Mar 01] Not only foil assisted, full flying: http://imca-wa.freeyellow.com/index.html. -- Tom Speer (firstname.lastname@example.org); website: www.tspeer.com; fax: +1 206 878 5269
[6 Mar 01] I have designed a 16' 100lb 2-person monohull foiler using two(only) fully submerged foils; should be sailing in 2-3 months. Take a look at the Hanno Smits website (listed under websites of IHS members) for info on his work with SP foils and a FLYING DUTCHMAN. Personally, the Aussie work on their Moths is most inspirational and should lead to light weight production monohull foilers that while not as fast (top end) as some multihull foilers will provide the thrill of flying to a much wider audience. -- Doug Lord (email@example.com)
Hydrofoils Excluded From TheRace2000...
[9 May 00] TheRace headquarters has admitted that they limited the entry of our hydrofoiler for the No Limits Race around the world. Their discrimination against foils has seriously impeded the development of effective offshore sailing hydrofoils. Our potential sponsor withdrew when our entry was denied. If they reverse the decision now, there is still a chance to pull it off. The prototype is complete. Our nine foot wide horizontal spans are designed to retract when we hit the inevitable obstacles. Please email firstname.lastname@example.org with a copy to email@example.com and ask them why they are discriminating against hydrofoils and why they still call this a "no limits" event. You can make a difference. Thank you for your support. Peter Murray firstname.lastname@example.org Tel.#(1)561-286-2643
VOLANTIS 60' Sailing Trimaran...
[12 Feb 00] I just attended a meeting of the Northwest Multihulls in Seattle where Duff Sigurdson of Canada presented the latest news on the 60 foot trimaran planned to be built in Hawaii. Sam Bradfield has designed the foils thus she will have inverted T-foils and small amas. Nigel Irens is the designer. They plan a solid wing with reefable/furlable center section, and a hard vertical tab on the lower leech of the rig for depowering. It looks like a more delicate Rave Trifoiler, with a single CF gull-wing crossbar. I was impressed, even considering that Queen Elizabeth II is supposed to christen it. It is not immediately clear that "Volantis" is meant for The Race. Burt Rutan will build the foils in his "Composites" shop in the Mohave Desert, and the majordomo is Adm. Stuart F. Plott, formerly head of seaborne infiltration efforts during the late unpleasantness in Vietnam. Duff also talked about aquatic satellites- small versions of the hardsail trifoiler that would be permanently at sea, monitoring the shipping lanes and seaport accesses, video-monitoring incoming ships for oil dumping/bilge pumping. Solid wings again? Please contact Duff Sigurdson for more accurate news- he is the new publicist: formerly associated with the Ronin project for The Race. -- Dave Carlson (email@example.com) website: www.fastsail.com/catcobbler/
Moth Class Sailboat Races With Foils...
[25 Feb 00] In a world first, Western Australian International Moth Class dinghy sailor Brett Burville has cracked it with a Foiler Moth, winning outright two heats of the World International Moth Class Championships held in Perth last week and finishing a creditable 10th place overall. The International Moth class is one of the few truly development International sailing classes and also allows foil development. At times Brett was travelling at up to 1-1/2 times the speed of the top existing designs and easily won the races in which he stayed upright. This is no mean feat, keeping in mind that an existing Moth can outpace a 505 and is already the fastest 11' monohull in the world. Brett's boat is a standard Moth, with a larger-than-usual T-foil on the rudder and forward V-foils mounted at the end of the wings. It appears he showed bursts of incredible speed in the stronger winds, punctuated by many capsizes. Clearly there is scope for further development, perhaps with some form of sensor control. He was foilborne above about 8-10kts of wind and sailed both downwind and also upwind on the foils. In the light wind races he removed the foils from the simple mountings in a couple of minutes. This is a major achievement, as most foilers to date are only reaching speed machines, like sailboards. This is the first time ever for a foilborne craft to compete successfully around the buoys in all conditions in a truly international standard sailing competition. It is hoped that Brett will produce some further details and it is expected a lot of further development will now proceed, as it is possible to take any existing Moth and truly revolutionise its speed in winds over 10 knots! Who will be first to take it further?? -- Ian Ward (firstname.lastname@example.org)
[25 Feb 00] See also the article and photos in the Jan 25, 2000 Sailing News from Boating Oz. Also, information and photos from various sources was reprinted in the Spring 2000 edition of the IHS newsletter.
Racing Boat Design Source...
[2 Apr 99] Does anyone know where you can get designs for jet boats (sport/racing versions - not fishing/commercial)? Please email me. -- Mathew Davies (email@example.com)
[3 Apr 99] The following groups run both propeller boats and JET (impeller) boats in various classes. The prop boats are quicker but both achieve speeds in excess of 200 mph regularly. Contacts (Hope the phone numbers are current.):
Liquid Quarter Mile magazine (909) 989-1169
IHBA International Hot Boat Assoc. (714) 634-4422
ADBA American Drag Boat Assoc. (216) 543-9647
NJBA National Jet Boat Assoc. (714) 993-2664
SDBA Southern Drag Boat Assoc. (817) 662-0774
-- Ken Cook (firstname.lastname@example.org)
[Date/Time=03-23-2002 - 12:58 AM] Name:Webmaster@foils.org [Msgid=237130]
[Date/Time=03-24-2002 - 2:01 AM] Name:email@example.com [Msgid=237508]
[Date/Time=03-24-2002 - 12:16 PM] Name:firstname.lastname@example.org [Msgid=237618]
[Date/Time=03-24-2002 - 3:26 PM] Name:email@example.com [Msgid=237691]
[Date/Time=03-25-2002 - 4:09 PM] Name:Webmaster@foils.org [Msgid=238105]
[Date/Time=04-20-2002 - 4:44 PM] Name:Doug Lord firstname.lastname@example.org, [Msgid=249625]
I have seen many multihulled sailing Hydrofoils and a few Centerboard/daggerboard/leeboard Monohulled sailing Hydrofoils. I have also seen Cantable Daggerboards and keels. I have never seen the combination you describe.
Are the Foils fully submerged and attached to the keel or are the foils separate from the keel?
At 42 inches, you might want to also post this message in the Sailing model section.
[Date/Time=04-20-2002 - 4:59 PM] Name:Bill White email@example.com, [Msgid=249626]
When you say Keelboat, I understand that to mean a sailboat with a centre keel? I am not aware of any such boat adapted to run foilborne. Looking though a publication by AYRS on sailing hydrofoils indicates that most experiments with sailing hydrofoils have tended to use hydrofoils mounted on outriggers or catamarans. In the case of monohulls, the foils are usually mounted off wide crossbeams and there is no keel below the hull in those case. The nearest I can come up with compared to what you outlined are a number of International Moth class sailboats that have been designed with hydrofoils fitted rather than the usual centreboard. Photos of these craft can be seen on the International Moth Class Association of Western Australia website at:
I am curious about your own concept so I hope we will hear more about it from you down the track?
[Date/Time=04-25-2002 - 7:47 AM] Name:Martin Grimm firstname.lastname@example.org, [Msgid=251569]
[Date/Time=05-04-2002 - 8:24 AM] Name:John Thomason email@example.com, [Msgid=255277]
Take a look at our books page http://www.foils.org/popbook.htm. There are some titles on this subject, all out of print I believe. However they can be obtained with a bit of effort from a library, used bookstore or the eBay on line auction site.
The Amateur Yacht Research Society has published a number of technical papers on the subject of hydrofoils, and these are all still available. There is a link to AYRS from our links page at http://www.foils.org/linksout.htm
The IHS has for sale the set of David Keiper files on adding foils to cats, however this design work was aimed at much smaller Beach Cats. Info on these files is at http://www.foils.org/ihspubs.htm. After David Keiper died, his work was continued and perfected by Dave Carlson. His email and website addresses can be found on our site by using the search engine on the main page. He is a good source of practical as well as theoretical information.
You might want to consider getting a boat that is already foil equipped and was designed for it. The Catri is such a vessel. Information is on our site at http://www.foils.org/catri.htm and at http://www.foils.org/catri.pdf. When the designer Aldis Eglais first corresponded with us, he was offering to sell just the plans or the plans plus kit as an alternative to buying and shipping a fully manufactured vessel... don't know if this is still an option.
Anyway, just some thoughts that may be of use to you.
[Date/Time=05-04-2002 - 8:27 AM] Name:Barney C. Black firstname.lastname@example.org, [Msgid=255279]
Over the years I have seen many mods made to Stiletto Cats. The Stilletto has always seemed to draw out the adventurers in the sailing world due to their High performance and rasonable price. They have very light foam sandwich hulls which might be very difficult to attach foils to, if you can not entirely use the crossbeams.
I have not seen any Hydrofoil conversions but many other Stilletto projects can be found in back issues of Multihull Magazine, Quincy Mass.
They have a web site and their owner publisher is very user friendly.
Best of Luck
[Date/Time=05-04-2002 - 9:23 PM] Name:Bill White asst Webmaster email@example.com, [Msgid=255479]
Bill White of IHS asked if I would share my experiences in developing and sailing a small sailing hydrofoil. I am happy to do so. Below is a brief account of my 10 year adventure with PK.
Thanks to my web site (and the International Hydrofoil Society site), I look forward to and receive a lot of e-mails on PK Hydroptère de loisirs (Small Hydrofoil Sailboat. The address of this site changed last month.
The new address is: http://membres.lycos.fr/monsonnec/
(Editors note: This is an extensive personal site of sailing hydrofoils)
I started the design of PK in 1992 and the construction in 1993.
This boat is exclusively made with some "Recycled materials"! For example the rail of the "rotary bench", is an old bicycle wheel! As a result, I designed and built PK for approximately $800 £.
PK flew the first time in 1997 without the system for the modification of the incidence and with a classical cat boat sail. When I sail I don't want to have some spectators chuckle (if PK don't fly!) and that's the reason why, I just have bad photos of PK in flight!
The latest version, (it's the same hull and floats since the start, but I changed all the other parts), has been ready since last summer (July 2001). Unfortunately I have had a problem with my backbone since the same date! As a result, I don't know if I am going to sail soon and I don't have photos of this version on the sea!
The particular points of this latest version of PK are:
Rigid rig and sailboard sail
T foils with " incidence control system"
Rotary floats (to protect the foils)
Length Overall 5 m
Length Hull 3.85 m
Beam 4.8 m
Sail area 7.5 m2
Weight 70 Kg
Built For Only $800.00£!
Please note that I cannot send the plans of PK, because I am not a naval architect and I think PK is not perfect, it's just a prototype! However, I would be happy to discuss her design and construction over the IHS Bulletin Board.
Thank you very much
I have enclosed different photos of PK at diverse ages below:
Before the first test of the fifth version in 1997: PK5 Stern-97
and PK5 Bow view-97:
Central hull during the first flight in 1997:
First test of the "incidence control system" in 2000:
PK6 in my garden last year! :
[Date/Time=07-04-2002 - 4:22 PM] Name:Raiola Giancarlo firstname.lastname@example.org, [Msgid=278825]
Attached File "PKxICS-00~jpg.zip" - size 40357 Click Here To Download
normal sails. I wonder if one could power some sort of lightweight 1-seater hydrofoilbuggy. It's obvious though (after finding the IHS-site ;-), that I still have quite some reading to do... Thanks to everyone at the IHS for making that possible ! -- Bart Derks,
[Date/Time=07-12-2002 - 7:57 PM] Name:Bart Derks email@example.com, [Msgid=281893]
[Date/Time=07-12-2002 - 7:59 PM] Name:Barney C Black firstname.lastname@example.org, [Msgid=281897]
[Date/Time=07-12-2002 - 8:01 PM] Name:Tom Speer email@example.com, [Msgid=281901]
There is a lot of Kite Board sailing on the Outer Banks at Cape Hatteras where I vacationed a few weeks ago. The boards are short versions of windsurfers boards or more like snow boards.
If I had the time and was a bit younger I think one could add a set of Hydrofoils to these kite boards and about double the speed. The foils would be similar to the ones that have been adapted for water skiing. There are several on our IHS web site at http://www.foils.org/linksout.htm#buyit
A good example is the sky ski http://www.skyski.com/home.htm
Best of luck
[Date/Time=07-13-2002 - 12:00 AM] Name:Bill White firstname.lastname@example.org, [Msgid=281938]
available hydrofoil trimaran. I see a lot of articles on your website about sailing hydrofoils, but nothing about the Windrider Rave. Their website is http://www.hydrofoils.com, and http://www.windrider.com. The Dutch over here claim a max speed of 41.5 knots, and I read that a French sailor has even gotten to 43 knots with the Rave.
Another sailing hydrofoil I noticed, is the hydroptere, http://www.hydroptere.com, and is mentioned on your site.
[Date/Time=09-14-2002 - 11:27 AM] Name:Mark-Jan Bastian email@example.com, [Msgid=309662]
[Date/Time=09-14-2002 - 7:57 PM] Name:Frédéric Monsonnec firstname.lastname@example.org, [Msgid=309784]
Thanks for the inputs. We do mention the Windrider Rave model on our Links page at http://www.foils.org/linksout.htm. Their web address keeps changing, so we appreciate the input so we can keep it current. The Rave is an exciting boat to see in action, though I have never seen it at the speeds you mention.
IHS BBS manager
[Date/Time=09-23-2002 - 7:04 PM] Name:Bill White email@example.com, [Msgid=313647]
[Date/Time=09-24-2002 - 9:15 AM] Name:Doug Lord firstname.lastname@example.org, [Msgid=313860]
[Date/Time=09-24-2002 - 10:37 AM] Name:Scott Smith email@example.com, [Msgid=313899]
The Hobie Tri-foiler certainly has a neat and simple foil control system, but the 'wand' approach used on the 'Rave' also seems to work well. From what I have read about sailing the Rave, it should not be necessary to manually control the foils to keep the boat flying in a stable manner. There is however a capability to control the foils manually if that is what the crew want to do.
Christopher Hook, who first developed a workable fully submerged hydrofoil craft, employed manual surface skimming attitude sensors that projected far forward of the bow foils. Apart from looking somewhat ungainly, these would undoubtedly have been subject to a fair bit of damage in service, even if just bumping into a wharf occasionally. I have often wondered whether it is really necessary for such mechanical surface sensors to actually project far forward of the foils. The Rave seems to demonstrate well enough that this isn't necessary as it runs well in waves while foilborne. For small waves that are typically short, it is not necessary for the hydrofoil craft to react to them by rising up, rather it can just continue through them straight and level. Having a foil sensor far forward is therefore no advantage in that case. For long waves relative to the boat it does not matter much whether they are detected directly in line with the foils or one or two metres in front of the foils as the wave elevation will not be very different between those locations. It would therefore only be for waves that are around the length of the boat that the position of the surface sensors would have a noticeable effect on the motion of the craft.
A question someone may be able to answer: For large electronically controlled fully submerged hydrofoils like the Boeing Jetfoil and PHM that could happily cruise in large waves at 40+ knots, how far ahead of the boat did the bow mounted surface sensor actually look to detect oncoming waves? How did the signal from that sensor get coupled with the signals from all the accelerometers mounted around the boat that were also used to achieve a smooth ride?
By the way, there is some nice footage in the video by Arcadia Entertainment "Hydrofoils - Flying on water" that shows a Rave doing a 180+ degree turn (downwind) in the blink of an eye, and remaining foilborne for a good portion of that evolution. Given that can be done, tacking the Rave while remaining foilborne would seem straightforward.
[Date/Time=09-26-2002 - 7:41 AM] Name:Martin Grimm firstname.lastname@example.org, [Msgid=315018]
[Date/Time=09-26-2002 - 8:38 AM] Name:Scott Smith email@example.com, [Msgid=315058]
As for the height sensors they where mounted looking directly down at the water. The ACS control system was set up to maintain a constant 1 "g" force on the deck via accelerometers and gyro's. The Hull mounted accelerometers where located on the PHM at the to rear struts and the forward one was mounted just aft of the forward strut. The accelerometers dampen out the effects of the height sensors seeing chop by clamping the signal to the hydraulic systems.
[Date/Time=09-28-2002 - 11:30 AM] Name:"Jake" Jakobson Jakobson@bellsouth.net, [Msgid=316107]
Thanks for your reply. I follow what you are saying about the dynamics of sailboats and the effect of the scale on the motions of a craft.
Just reinforcing your point about scale, for a case where all proportions of a boat and the waves it is travelling in are scaled down and if the speed of the boat is also "Froude Number" scaled, the time period in which successive waves are encountered is reduced by a factor of the square root of the ratio of model to full size length. For example, a 1:20 scale model of a hydrofoil boat will encounter the corresponding "1:20 scale" waves in only 22% of the time of its full size counterpart, or around 4.5 times faster.
Although there is an agent for the sale of the Windrider Rave in Australia, I have not seen any first hand. I have not seen any Trifoilers either so I can't comment about their relative characteristics!
[Date/Time=09-28-2002 - 9:12 PM] Name:Martin Grimm firstname.lastname@example.org, [Msgid=316268]
Thanks for that straightforward response to my question. It beats trying to find that out by tracking down and then reading through long and complex technical papers!
[Date/Time=09-28-2002 - 9:16 PM] Name:Martin Grimm email@example.com, [Msgid=316270]
We should also not forget the amazing development by Rich Miller of the first true and only "monofoiler", a high performance sailboard with just one foil in the water..like a unicycle!
[Date/Time=11-11-2002 - 1:43 AM] Name:Ian Ward firstname.lastname@example.org, [Msgid=336265]
If you would like I'll be more than happy to add your boat to the others on www.monofoiler.com
When did you first sail your boat on two foils?
Congratulations on a great job! Doug Lord email@example.com
[Date/Time=11-11-2002 - 8:19 AM] Name:Doug Lord firstname.lastname@example.org, [Msgid=336328]
[Date/Time=11-22-2002 - 4:05 AM] Name:Barney C. Black email@example.com, [Msgid=341779]
Also, adding words is a valid resource in both languages, exactly as in Latin or Greek. For example: "pepó" is derived from "pe" + "pó" = "flat" + "hand".
As a consequence, the word "Hydrofoil" can be translated directly into "Y'pepó" and the meaning is clear in the course of normal conversation. The roots were double checked in three different Guarani dictionaries and two Tupi dictionaries and the correctness of the composed word was verified with many Guarani speakers, among them two teachers of the language.
I searched for this word while trying to find ideas to name my future hydrofoil assisted folding trimaran model "Catri 27R" designed by Mr. Aldis Eglajs, from Latvia. By the way, I found and read his text in your website before my first contact with him and now the boat will be the first of a serial production in Brazil. I shall name it "Y'pepó" if my wife and daughter allow me...
[Date/Time=11-24-2002 - 9:15 AM] Name:Luiz Schechter firstname.lastname@example.org, [Msgid=342713]
[Date/Time=12-03-2002 - 5:57 PM] Name:Byron E. Wallin email@example.com, [Msgid=346366]
Unfortunately, Dave Keiper died and the book has gone out of print, along with the companion videotape of WILLIWAW. IHS first attempted to interest some publishers in the idea of reprinting this book commercially, but was unsuccessful. Then, IHS had the idea to create an E-Book version with clips from the video to be offered at cost on CD-ROM. We even went so far as to scan the book into Adobe Acrobat with bookmarks, internal hot links, and full optical character conversion. In fact, the remnants of Dave's website as preserved by his brother Frank state (incorrectly) that the eBook is available (see http://www.wingo.com/dakh/voyager.html). Unfortunately however, we were not able in the end to get unanimous consent to offer the book in this fashion without remuneration to the heirs.
Meanwhile, this excellent book remains unavailable to the public; I have not seen even one copy go up for auction on eBay over the years since Dave died. Attention is shifting inexorably away from Dave's legacy in the hydrofoil sailboat field to focus on currently active efforts such as the racing Moth Class experiments with foils and the Catri sailboats designed by Aldis Eglajs. At one point, IHS member Tom Speer was planning a follow-on to WILLIWAW (see http://www.basiliscus.com) but I do not know the current status of this idea; the site was last updated in 2001.
The key to getting permission to reprint the book is to interest a commercial publisher or other company to do so in a way that would benefit the heirs financially. IHS was not able to do this, but we certainly did not exhaust all possibilities. Perhaps someone else would be willing to tackle this.
[Date/Time=12-03-2002 - 6:25 PM] Name:Barney C Black firstname.lastname@example.org, [Msgid=346383]
We seem to have an amazing resource of such talent within the IHS ranks, and I am sure we could together pro-actively design a better Moth based on hydrofoils and come up with a really good, simple, light and cheap foiler dinghy for everyone to enjoy!
It would be good if IHS would sponsor a special development discussion section on the website, where perhaps some other members or interested parties may be able to contribute answers and ideas to many of the questions that I have. For example:
Why can't I sail foilbourne upwind in under 15kts of wind, how to fix this?
Is semi foiling upwind faster than displacement sailing?
Would a foiled bow rudder work?
How to maintain control at high speed?
Why can't I sail foilbourne upwind in under 15kts of wind, how to fix this?
[Date/Time=01-04-2003 - 3:07 PM] Name:Ian Ward email@example.com, [Msgid=358650]
[Date/Time=01-05-2003 - 2:59 PM] Name:jim hynes firstname.lastname@example.org, [Msgid=358944]
[Date/Time=01-06-2003 - 8:10 AM] Name:Dr. Raul Díaz Langou email@example.com, [Msgid=359235]
[Date/Time=01-06-2003 - 2:53 PM] Name:vincent browne firstname.lastname@example.org, [Msgid=359379]
You have made a nice observation. I tend to find it hard to understand how hydrofoils with such apparent little transverse stability as the current series of fully submerged sailboats with only centreline foils can be operated, yet Ian and others have shown it can be done! That doesn't only apply to these sailboats and the air chair water skis that you also mentioned, but also solar powered one-man hydrofoils, pedal powered hydrofoils and now even hydrofoil surfboards!
For those with a really technical bent, the mathematical modelling of the human operator using skilful body weight shift to maintain stability of a solar powered hydrofoil has been examined in the following reference:
Terao, Yutaka; "Lateral and Roll-Yaw Coupled Motion Control of Hydrofoil Craft", Proceedings of the 7th International Conference on Stability of Ships and Ocean Vehicles (STAB 2000), 7-11 February 2000, Launceston, Tasmania, Australia. AMECRC Ltd, Editor: Martin Renilson. pp 542 - 550.
For me, I just prefer to see these spectacular craft running foilborne. The Arcadia Entertainment "Hydrofoils - Flying on Water" video shows some good footage of such solar and human powered craft and air chair water skis in action.
[Date/Time=01-07-2003 - 12:41 AM] Name:Martin Grimm email@example.com, [Msgid=359572]
[Date/Time=01-09-2003 - 1:23 PM] Name:Barney C Black firstname.lastname@example.org, [Msgid=360565]
I am interested in adding fins to the sterns of the catamaran, to help
reduce pitching while sailing and motoring into chop. My question is, can you recomend a person or company that could help me evaluate the possibility of adding fins to my cat to help give it a better motion while moving through chop/ waves?
As you can imagine this is a recreational sailboat, and I would only add fins to my cat if it is something that I can do economically (they would be fixed fins).
[Date/Time=01-24-2003 - 1:59 PM] Name:Tony Amador email@example.com, [Msgid=366530]
[Date/Time=01-25-2003 - 6:26 PM] Name:Michael W. Preis firstname.lastname@example.org, [Msgid=367041]
[Date/Time=01-26-2003 - 8:21 AM] Name:Tom Speer email@example.com, [Msgid=367269]
I tend to agree with Michael. If you want to reduce pitching motions, it would probably be better to add an anti-pitching fin or fins as close as possible to the bow of your boat.
The Royal Australian Navy fitted an anti-pitching fin to the bow of its mine hunter catamarans and this seems to have been beneficial in reducing pitching motions. The fin spanned the entire gap between one hull and the other. These craft had a speed of about 8 knots but would have had a displacement significantly greater than your own boat.
Unless the fins are particularly well designed, you should anticipate some speed loss due to the additional drag that they will create. Also, there is a possibility that in some sea conditions, such as in following seas, the pitching motions may become worse if the fins are purely passive.
[Date/Time=01-26-2003 - 8:52 AM] Name:Martin Grimm firstname.lastname@example.org, [Msgid=367276]
[Date/Time=01-28-2003 - 7:51 PM] Name:Byron Wallin email@example.com, [Msgid=368609]
[Date/Time=01-29-2003 - 9:57 PM] Name:Barney C. Black firstname.lastname@example.org, [Msgid=369337]
[Date/Time=02-04-2003 - 1:46 AM] Name:Tom Speer email@example.com, [Msgid=371849]
As far as I know the HYSUCAT approach hasn't been applied to sailing catamarans yet. Maybe a foil stretching between the sterns?
[Date/Time=02-08-2003 - 2:46 PM] Name:Tom Speer firstname.lastname@example.org, [Msgid=374632]
My name is Gérard Delerm (I am french)
I already show my home page about "Le Foilboard" on the IHS site.
It is a sailboard with hydrofoils project.
There are now somes updates in the english version (link NEWS on the contents page).
[Date/Time=02-10-2003 - 9:00 AM] Name:Gérard Delerm email@example.com, [Msgid=375459]
Any comments or thoughts are appreciated.
[Date/Time=02-24-2003 - 4:39 AM] Name:Rohan Veal firstname.lastname@example.org, [Msgid=383699]
[Date/Time=03-15-2003 - 2:31 AM] Name:Steve Salani email@example.com, [Msgid=396535]
[Date/Time=03-19-2003 - 5:21 PM] Name:Henry firstname.lastname@example.org, [Msgid=399556]
I figure that at 8 to 10 knots I would like to get around 3-400 pounds of lift TOTAL from all four hydrofoils. This would allow a couple of people to ride forward on the cat without hurting performance and would keep the bows up when maneuvering in wind and waves.
I have no idea if this is a practical solution to this problem. If it is I have no idea of the actual size of the hydrofoils. So I am soliciting ideas from those who know much more than myself about this sort of thing to try and lead me to a reasonable decision as to whether or not I should try this.
[Date/Time=05-26-2003 - 8:24 AM] Name:Paul Cowles email@example.com, [Msgid=441573]
[Date/Time=05-26-2003 - 8:56 AM] Name:Paul Cowles firstname.lastname@example.org, [Msgid=441586]
I think the best answer is to use pivoting foils, with a sensor. This way you can always get optimum lift. If you are adventureous the HYSUCAT idea may also be a winner. see http://www.hydrospeed.co.za/
An alternative is to put T foils on the rudders to reduce pitching and diving. This works quite well, involves no moving parts and is simple to add.
[Date/Time=05-26-2003 - 11:23 PM] Name:Ian Ward email@example.com, [Msgid=441941]
Be Sure to check out our IHS Archives: Posted Messages and Frequently Asked Questions (FAQs) at
They contain lots of information from earlier converstations on this subject.
[Date/Time=05-28-2003 - 6:39 PM] Name:Bill White firstname.lastname@example.org, [Msgid=443265]
[Date/Time=06-03-2003 - 7:32 AM] Name:Gerry Levine email@example.com, [Msgid=446222]
[Date/Time=06-05-2003 - 6:41 AM] Name:Scott Smith firstname.lastname@example.org, [Msgid=447375]
[Date/Time=06-15-2003 - 6:36 AM] Name:Barney C Black email@example.com, [Msgid=452969]
[Date/Time=06-18-2003 - 6:11 PM] Name:Gérard Delerm firstname.lastname@example.org, [Msgid=455251]
I have recently modified an old non-winged scow Moth hull, placed a single foil on the centreboard and a retractable surface running foil at the bow. No rudder T foil at all. Total cost of materials to make the foils is about $200, even less if you simply modify your existing centreboard!.
I took it out last Sunday and got it up and going in about 10-12 kts of wind. There are many things to improve yet, but in principle it all works fine, no capsizes and some good bursts of speed on reaches!. It is really amazing to realize it is possible to sail with only ONE foil in the water!.
The principle is not new, Rich Miller has a sailboard already doing fantastic speeds up to perhaps 35 kts with a similar arrangement. This is just the first application to dinghies. There is a long way to go yet, but 35kt Moth is a real possibility
This means it is possible to use existing, old boats and adapt them to foils. I see no need for a new range of specialist hulls just for foiling. In fact some of the older and more stable hulls may perform even better as they are still good in light winds. It is also relatively cheap to make the necessary modifications. The boat is launched in the same way as a normal dinghy. In conclusion, it is indeed possible to have a low cost, high speed, easy to handle foiler suitable for begginers and speed demons alike.
In my opinon, most of the fears about foiling in sailing circles comes from not being able to imagine what is possible, not actually having a go and even worse, doing nothing to actively develop a solution! Some of those who looked at the original Brett Burville trifoil Moth contraption were horrified at its ungainly, impractical but fast foils and immediately wanted to ban these from the Moth class.
It is only with imagination and some real drive from the Isletts, Rich Miller etc that we have made real progress, and I am sure there is a lot more to come in terms of simplification, speed, handling and low cost! There is only one way to find out, I encourage all of you to give it a go and develop your own solutions!
I believe the International Moth class should be proud to be the only International sailing class currently prepared to allow foil development.
Without such an open forum, Moths would have remained Scows and foiler development would have ceased at Trifoilers.
In the long run I am sure Moths and all future sailing classes will benefit.
[Date/Time=11-10-2003 - 9:39 PM] Name:Ian Ward email@example.com, [Msgid=541387]
Thank you for your message and congratulations for your work. Can you show somes pictures about your project please ?
[Date/Time=11-20-2003 - 1:00 PM] Name:Gerard Delerm firstname.lastname@example.org, [Msgid=547448]
He has won five races against 30 plus boats by leads of three to nine minutes. In the race he won by nine minutes second place was also a hydrofoil!
Rohans boat sails on just two foils: one on the daggerboard and one on the rudder. Altitude control is by use of a "wand" system. Stability is provided
entirely by the crew. The boat and foils were built by John Ilett of Perth Western Australia and he deserves congratulations as well.
Way to go Rohan!
[Date/Time=01-03-2004 - 8:35 AM] Name:Doug Lord email@example.com, [Msgid=566079]
[Date/Time=01-03-2004 - 9:43 PM] Name:John Ilett firstname.lastname@example.org, [Msgid=566365]
[Date/Time=01-04-2004 - 12:43 AM] Name:John Ilett email@example.com, [Msgid=566418]
Image Attached: "Rohan-QLD.jpg" Click Here To View
does a planing hull beat a displacement hull to 10 kts boat speed in lighter wind conditions.
what im trying to acheive is lift off in a wind range between 5 - 10 kts and after that i would like a low aerodynamic drag hull. im thinking of something similar to a formula sailboard for its planing but am concerned about the wetted surface area as opposed to a displacement hull similar to a rowing skull. although i only have 11 feet of LOA (width currently runs around 1ft)
ps: consider the weight of each hull to be the same.
[Date/Time=02-04-2004 - 10:38 AM] Name:glen oldfield firstname.lastname@example.org, [Msgid=583861]
If you were considering a larger boat, say one carrying several people, then the answer would definitely be that a slender displacement hull would have less resistance at 10 knots. If on the other hand you are looking at something as small and light weight as a Moth, then it is harder to clearly identify the best option as there will be a transition of least resistance from the displacement hull to the planing hull at a speed around what you are interested in.
In the Moth size range, the best performing boats these days seem to be the very slender displacement types. In higher wind speeds it could be expected that a planing hullform should give lower resistance. Of course by that stage, if foils are fitted, the hull should be clear of the water under those conditions anyway!
[Date/Time=02-14-2004 - 9:19 AM] Name:Martin Grimm email@example.com, [Msgid=596593]
[Date/Time=02-18-2004 - 1:41 AM] Name:Ray Vellinga firstname.lastname@example.org, [Msgid=598753]
we're organizing a speed race over in Douarnenez (France). Different categories are invited to run : windsurfers, kitesurfers, multiholls 60 feet and hydrofoils[/b. I'll give you more information next time but for now, could you please give me some contacts of people eventually interested by that kind of races ?
Waiting for your answer,
Société des Régates de Douarnenez
57 quai de l'yser
[Date/Time=05-26-2004 - 11:32 AM] Name:Anne Raffray email@example.com, [Msgid=654338]
[Date/Time=05-31-2004 - 8:01 AM] Name:Barney C Black firstname.lastname@example.org, [Msgid=656322]
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