Archived Messages
Count,MessageID,category,ShortTitle,Message,Date,UserName,MsgPswd,Phone,Email,ParentMsgId
"1","912645","3","Re; Re; Re; A faster pontoon boat||912645","FYI: Several people around the USA are working on adding foils to pontoon boats... hobbyists, not manufacturers. Their correspondence with IHS is archived and accessible. Go to the main IHS page at www.foils.org and use the PicoSearch Engine to look for the word "pontoon." That will lead you to several citations.","2005-10-12","Barney C Black","poopdeck"," "," ","911944"
"2","911944","3","Re; Re; A faster pontoon boat||911944","There's a company in Canada www.u-fabboats.com that I have shared what I learnedand are planning to offer a foil kit on there pontoon boats. It will be a hydro-foil assisted with a fixed foil in the tunnel. Which will reduce wetted surface I guess thats what it's all about? I been playing around with a fixed foil and have had much luck with it I was focusing on slow speed. 12 mph and she's on a plane and thats at gross weight I am planing a motorsailing cat around this concept.","2005-10-12","Mike","nopswd"," ","info@buildboats.info","888662"
"3","888662","3","Re; A faster pontoon boat||888662","I have thought about this as well. Trick is, don't get too high out of the water. It is tempting to want to run the hull 3 feet out of the water to skim through wakes, but a sudden drop will be more than the hull was designed for. Lifting the hull 10 inches will give you speed and fuel economy, with less structural risk. Raising and lowering an outboard is a great way to accomplish powering the boat. I would be concerned about what will happen when the foils hit something (and they will). A front foil centered between the hulls could pivot back up between the hulls. The rear foil or foils could be fixed to the structure behind the hulls, and pivot up when trailering or running shallow. The trick (as I have learned from my dynafoils) is to have the rear strut mounted so that the foil is in front of the pivot point. That is, the rear strut(s) would go from the pivot point at an angle, the bottom of the strut forward of the top of the strut. Helps keep weeds off too. Why is this important? If the rear strut is vertical and operates on a pivot, after striking debris the strut would begin to pivot backwards. As it does the foils angle of attack changes. At some point in the travel the foil will be perpendicular to the drag load placed on it and it will not rotate up out of the water. Kiss your transom goodbye, keep pliers handy to pull your teeth out of the dashboard. If the foil is forward of the pivot things change. The foil will become perpendicular to the direction of travel while still well below the axis point. By the time the strut rotates far enough to line the center of drag up with the centerline of the structure, the foil is now operating backwards with positive lift. This forces the strut to continue rotating up and out of the water, saving you a lot of pain.
If you would like to take a look at the dynafoil system, or just talk, feel free to drop me a line. I just moved up from Miami to Stuart. By the way, a lot of talk goes into how to control roll in hydrofoils. While this is a concern with ships, I am convinced it is far less complicated with smaller boats. If you have ever ridden a bicycle I'm sure you have learned that you already have the ability to overcome roll issues with steering. After a while you don't even realize you are doing it.","2005-09-05","Scott Smith","nopswd"," ","boatswithwings@adelphia.net","3"
"4","853019","3","Re; Re; A faster pontoon boat||853019","Good luck with your project. Hope this helps.
Bob's Machine Shop make the motor lifting plates you need. You can find them at.
http://www.bobsmachine.com/
Several catamaran builders and designers make the keel mounted foils systems you are talking about. See for instance the Hysucat Hydrofoil System.
http://admin.sun.ac.za/kie/unistel/technologies/foiltech.htm","2005-06-29","william white","nopswd"," ","whitewn@speakeasy.net","0"
"5","852923","3","Re; A faster pontoon boat||852923","I've been fighting that problem for some time. The easiest technique would be to jack the outboard motor up/down with spring-loaded and hydraulic jackplate. The rear foil which fits between the tubes, would move with the motor. A similar arrangement for the bow. If you allow the tubes to just skim the water that will keep the boat more stable. Make sure that going aground won't be catastrophic. I'd love to find someone "local" to work with on my pontoon project. barry_steele@yahoo.com","2005-06-29","Barry Steele","nopswd"," "," ","0"
"6","852922","3","Re; A faster pontoon boat||852922","I've been fighting that problem for some time. The easiest technique would be to jack the outboard motor up/down with spring-loaded and hydraulic jackplate. The rear foil which fits between the tubes, would move with the motor. A similar arrangement for the bow. If you allow the tubes to just skim the water that will keep the boat more stable. Make sure that going aground won't be catastrophic. I'd love to find someone "local" to work with on my pontoon project. barry_steele@yahoo.com","2005-06-29","Barry Steele","nopswd"," "," ","0"
"7","852376","3","A faster pontoon boat||852376","Living in Florida I spend a lot of my time on the water and most of it in the shallows. Pontoon boats offer the best way to take the party with me, slowly. A pontoon with retractable foils would be the best of both worlds. Any body out there tried this? I have given this a great deal of thought and have many ideas how to achieve this but expert advice is always welcome. Any advice where to look for info besides this excellent website would be greatly appreciated. Opinions on this would be welcomed aswell. ","2005-06-28","Brian Scott","nopswd"," ","brian.scott.ctr@hurlburt.af.mil","0"
"8","792474","3","TUCUMCARI||792474","Hello,
For the past 26 years I have served as a project supervisor creating museum exhibits in honor of U.S. vets and those of our allies. Some of the venues I have done work for include the USS Intrepid Sea Air Space Museum and the Museum of Polish Military Heritage in America, both in New York City. Load my name Mike Dobrzelecki into a Google Search Engine and you'll see examples of some of my work on two continents over the years.
I saw your name & email on the IHS website and hope you can provide some help on a research project concerning the Tucumcari PGH-2.
I built the old Aurora kit when it first came out in the late 1960's early 1970's (?) and not too long ago picked up a derelict unpainted damaged built-up, as well as a pristine complete kit still in the original box. I even still have some parts from my original build model.
My intent is to build one 'flying' and one in the water with its struts and foils folded up and possibly write a good article on the Tucumcari.
I have everything available on the internet for this fascinating hydrofoil, as well as, the old Sea Clasics issue with the Tucumcari on the cover. Recently, I obtained a copy of the History Channel Mail Call episode with the world's most famous D.I. narrating exquisite video of the this fast-fighting boat in action - great footage, BTW. I have even manage to track down some of its crew for personal interviews. Most frustratingly, the crew I talked to so far all stated that their photos went missing during moves over the years.
I am looking for more photos including details of the interior, the exterior fit on the cockpit/bridge and upper surface of the hull and an answer to what's in the large opening aft of the .50 cals and masts/antennae. I would also like to track down some more crew and any other books or naval history magazine articles on the the Tucumcari. Any leads would be appreciated.
Mike Dobrzelecki
3040 Clayton Street
Easton PA 18045
","2005-03-07","Mike Dobrzelecki ","members"," ","Michael_Dobrzelecki@fwc.com","0"
"9","737553","3","Foil or Log?||737553","I don't know what calculator you're using, but if it's telling you you can get good results from a section with a 50% thickness ratio and 25% "profile curvature" (camber?), I think you need to get a new calculator. These numbers sound like your foil section is a half-circle. Might there be just a little bit of flow separation coming off such a shape? ","2004-11-13","Tom Speer","nopswd"," ","me@tspeer.com","0"
"10","737001","3","Hydrofoil Design Validation||737001","I downloaded a hydrofoil simulation calculator and wanted to verify the results I am getting.
Can someone tell me if the following numbers are accurate? I am trying to get the highest amount of lift I can for a constant water velocity over hydrofoil of 20m/sec or 38.9Knots. I am also trying to keep the foil span as short as possible.
Here are the input numbers:
Foil Area Square Meters: 1 Sq M (1M span X 1M chord)
Speed M/sec: 20 M/sec
density of water kg/m^3: 1000
thickness of foil divided by chord: 0.5
Aspect ratio (Foil span/chord): 1 "This is a square foil I know"
Angle of attack: 14.32 degrees
Profile Curvature: 0.25
The calculation is claiming that the hydrofoil would produce 53690 pounds of lift with these numbers. I need to make sure this is true and also that the wing is not in a stalled state on these numbers.
Greatly appreciated. Sidenote: Would anything change if I put a rectangular ducting around the hyrdrofoil? I know in airfoils and fans, the ducting produces more volume of airflow.
BE","2004-11-12","Foiled Again","nopswd"," ","mirequest@yahoo.com","0"
"11","732177","3","Re: planing hull seakeeping||732177","I don't have a copy of these articles, but I would suggest contacting the Davidson Laboratory via their web page at:
http://www.stevens.edu/engineering/cms/
","2004-11-03","Barney C Black","poopdeck"," ","barney@alum.mit.edu","0"
"12","722280","3","planing hull seakeeping||722280","I am looking for copies of Gerard Fridsma's two publications:
Fridsma, G., “A Systematic Study of the Rough-Water Performance of Planing Boats,”Davidson Laboratory, Stevens Institute of Technology Report 1275, Nov. 1969.
Fridsma, G., “A Systematic Study of the Rough-Water Performance of Planing Boats - Irregular Waves Part II,”Davidson Laboratory, Stevens Institute of Technology Report 1495, March. 1971.
Can anybody supply me with copies of these?","2004-10-12","Gunther Migeotte ","nopswd"," ","gunther@cae.co.za","0"
"13","699947","3","Re: Engine Torque||699947","I have several small hydrofoils, probably similar to what you are trying to do. They are called Dynafoils (a search of the archive will turn up pics for you)and are about 8' long, similar to a one-person sit-down waverunner. They were available in two HP's, a 26hp model, and a 36hp model. Neither used a torque convertor. They used 2 cylinder, 2 stroke snowmobile engines, direct coupled to a 90 degree gearbox, to a downshaft with an evinrude outboard lower unit. The 26hp unit used a 9-1/4" dia. by 7" pitch prop, the 36hp unit uses a 9x9 prop. My 36hp Dynafoil leaps out of the water pretty well, and does about 35 mph. If you like, I can send you pictures, videos, or you can stop by in Miami and go for a test ride :)
If you are considering a 4-stroke, also consider a rev-limiter.","2004-08-26","Scott Smith","nopswd"," ","ssmith@syntheon.com","0"
"14","694448","3","Re; Re; Re; Engine Torque||694448","Barry,
Thank you for the information. What make is the prop...
","2004-08-13","Philip","nopswd"," ","kernowii@sympatico.ca","0"
"15","693009","3","Re; Re; Engine Torque||693009","For my application I have purchased a variable pitch prop for my mercruiser outdrive. The 3 blades to the prop are spring loaded with a lower pitch (around 16) for getting out of the hole and up on the foils. When the engine picks up speed, centrifugal force rotates the blades for up to about 25 pitch. This keeps the engine running within a fairly tight speed range. They are available for outdrives, outboards and inboards.","2004-08-11","Barry Steele","nopswd"," ","barry_steele@yahoo.com","0"
"16","692414","3","Re; Engine Torque||692414","Philip,
I would have expected that torque converters would rarely be required for small craft such as you describe. These devices result in a loss of power between the engine and the propeller and so a more efficient solution would be to select an outboard and propeller combination with an optimum gear ratio and propeller pitch to diameter ratio.
Hydrofoils have a resistance versus speed curve that means they require a relatively high thrust at takeoff speed and after that the resistance curve is more flat. Some larger hydrofoils (such as the Supramar PT 150) therefore had torque convertors of some form fitted to cope with this characteristic such that the engine would not be overloaded during takeoff but would run near optimally at cruise speed. For a smaller hydrofoil, there would typically be a surplus of power across the full speed range, but you may be adopting an outboard with relatively low power output so the takeoff condition may become critical for your boat.
Note that when using gearing in an outboard, the following relationship applies:
Power = (Torque) x (Rotational Speed)
Metric units for this equation are Watts, Nm and rad/s respectively.
Put another way, if you use a reduction ratio of 2:1 then the propeller shaft RPM will be half the engine RPM but the torque available at the propeller will be double that at the engine output shaft (neglecting any losses in the gearing due to friction). You can play with gearbox ratios until you obtain the required torque and RPM combination you need at the propeller. ","2004-08-10","Martin Grimm","nopswd"," ","seaflite@alphalink.com.au","0"
"17","687245","3","Engine Torque||687245","I’m currently reviewing a design for a small one-person hydrofoil powered by a 15hp-25hp long shaft outboard. The question of engine torque has arisen and the need for an engine mounted torque converter however; in reading a lot of the design material on these pages (excellent guidance by the way) I have yet to come across this issue being discussed. Is torque a major design consideration on small (<9 feet) hydrofoils?","2004-07-30","Philip","nopswd"," ","kernowii@sympatico.ca","0"
Propulsors
Arneson Drive For Sale
[2 Feb 02] This asd 6 drive is for sale. I think it would be a good drive for a hydrofoil. The drive is like new. Price $1,900. Credit cards OK. -- Fred Rodolf (FREDRODOLF@aol.com)
[Date/Time=03-23-2002 - 12:33 AM]
Name:webmaster@foils.org
[Msgid=237120]
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