Air injection for planing hulls

[CDK]

From my airforce days, long ago, I remember a unique feature of the Lockheed F-104 Starfighter plane.
Because the aircraft had unusually small wings, large flaps were needed to obtain enough lift at and below 200 knots. In addition, the flap angle was an extreme 35 degrees, causing air turbulence on the upper surface.
To resolve the problem, the designers used an air injection system. The rear wing edge had a row of small holes, connected to an air pump that was powered as soon as the flap angle exceeded a critical angle.

The above has nothing to do with boating, but is just a background for the following:

The friction between a solid surface and air is only a fraction of the hull-to-water friction. If a planing hull would have a row of holes at the beginning of the planing area, through which air was injected, there would be an enormous reduction of drag, resulting in a much higher speed and/or a lower fuel consumption. It might even me possible to reach planing speed with a much smaller engine that normally could never get the boat over the hump. The power requirements for the pump would be very modest, just a single V-belt and a vane type pump similar to the air injection pumps that were used in the automobile industry to meet CO requirements before the introduction of the catalytic converter.

Does anyone know of such an experiment being carried out? No skirts like on a hovercraft, just a row of holes, an air pump and of course a non-return valve to prevent water entering the boat when moored.

[rwatson]

The Lockheed method reminds me of the technique used by jacque cousteau for his 'solid' sails on his experimental wind assisted yacht.
The concept of injecting air bubbles in the water might have merit, but it would reduce bouyancy for the hull of course.
Should be easy to set up as a model experiment.

[mmd]

Yes. In 1995-96, I collaborated with a fellow designer to construct an air-lubricated planing catamaran hull for a Barbados client. The vessel, named "Ocean Mist", was 18.25m x 8.0 x 1.00m, arranged as an eight-passenger, three-crew charter boat. It was powered by twin 400-hp Cummins through conventional shafts & props, and achieved 31.25 knots during trials.

http://i32.photobucket.com/albums/d19/mmd_ns/OceanMistpowercat.jpg

Her owner sadly was diagnosed with cancer a few years after delivery and, after a valiant struggle, passed away two years ago. The boat was sold prior to his death and I have lost track of it.

[curridronan]

I know someone did a final year Bachelor Nav Arch thesis on this air injection into the boundry layer but it was on an Open 60 sailing yacht. I know that on hydrofoils (surface piercing) to alter the lift coefficient they use injection of air bubbles near the trailing edge of the upper surface of the foil to initiate early seperation. Also there is a method of shooting a fast stream/jet of water at the trailing edge to alter the stream speed over the foil.
I know alot of sailing rules (Open 60/Volvo 70/ AC90's/ ACC ver.5) stipulate that any device altering the boundry layer flow is forbidden. They mention devices to release films of varying viscocity over the hull and similar devices...
Another way to greatly reduce the viscous drag would be to resonate the hull at the frequency of the atomic forces that attract the fluid to hull...

[tom28571]

You need to differentiate between a hull that is partially supported by air pressure or an air/water mixture. Many suggest that injecting air into the water under the hull will lower skin friction. I don't know enough hydrodynamics to say but have read that introduced air bubbles increases total drag rather than decreasing it. As Watson says, it makes sense that adding air that does not support the hull by pressure will make the boat sink lower in the water to retain equilibrium displacement. Does this increase wave making and add to total drag? Some have run engine exhausts to the underside for the same purpose.

I know that many successful boats have used skirts at the chines to trap air and some even add blower fans for greater effect. These do work but are not widely used, maybe because the advantages are limited in practice.

curridronan's comments refer to rulings after some experimenters tried injecting long chain polymers into the boundary layer to reduce friction and retain laminar flow longer. This does work and so was outlawed in sailboat racing in the late 1960's I think. This method is used in industry to reduce friction in liquid in pipes, such as in steam powerplants.

[curridronan]

Tom, from what Im studuing about Marine Hydrodynamics (MSc. Yacht & Small Craft) a turbulent boundry layer has less skin friction than a laminar one that will almost always trip to turbulent which is difficult to calculate and therefore design for. The air injection I was talking about above is purely for a planing/semi yacht hull form, it does not affect buoyant forces as hull is planing anyway. And it is not an air cushion vehicle. Also riblets/especially roughened surfaces like swimmers suits take advantage of the turbulent boundry layer theory...

[eponodyne]

Golly, I'd think you'd need a pump capable of moving like a thousand cubic feet of air a minute to see any real improvement. I might be mistaken but wouldn't you need like eight times the air when your speed doubled, following the ccube function rule of thumb for horsepower? Or is that only in air and in a denser medium you'd need correspondingly more? Dunno.

[Guillermo]

Air injection has been treated in these forums in several ocasions, as per example in:
http://www.boatdesign.net/forums/showthread.php?t=14886

More radical use of air injection:
http://www.boatdesign.net/forums/showthread.php?t=10574

Cheers.

[Chris Ostlind]

A few years ago, I visited a website where a Danish designer had been studying the performance characteristics of classic Viking craft. His take was that they, quite often, had constructed channels in the hull from bow to stern in which an entrained air column moved while underway. This column functioned much like the air bubble trail you suggest, CDK.

Obviously, they had little in the way of pumping said air such as the bubble stream suggested. Well, unless you'd buy a Viking warrior sitting up at the bow running a blacksmith's manual bellows for the entire voyage. ;-)

Anyhow, I have lost connection with the Danish guy's website in the ensuing years since forst reading it. I do know that he had built several classic sailing boats, of the harbor and short coastal variety, using this entrained air channel technology and was reporting them to be faster than the non channeled version of same.

If anyone knows of this site, I'd love to get the URL and refresh my understanding of his studies.

Chris

[Guillermo]

More interesting info:
http://www.turbulence-control.gr.jp/PDF/symposium/FY2004/Kodama.pdf

Search internet for "microbubbles drag reduction" "microbubbles planning hull" or the like, to find out a wealth of info.

Cheers.

[tom28571]

This is all interesting for thought but I would sure like to see some objective testing and reporting.

It is difficult to believe that turbulent flow has less skin friction than laminar flow when so many engineers spend lifetimes trying to maintain laminar flow of wings and other foils. Of course that includes lift/drag ratios among other factors.

Anyway, whether a boat is planing or not, it still requires exactly the same lift force to hold it up. Buoyancy plus dynamic lift must equal the weight of the boat, unless Newton was wrong.

I'm reading the links above but it requires a lot of study to see it through.

[TollyWally]

Forgive my possible misunderstanding but isn't this very similar to what happens in an old fashioned step hydroplane? I was under the impression the the step created a sheet of bubbles that decreased the friction between the aft section of the hull and the water. Several modern go fast boats appear to have ducts that channel air to the aft areas of the hull.

National Fisherman published an article 10 years back or so about some experiments with a big airduct channeling air underneath an experimental power catamaran. They got quite a difference by opening or closing the top of the air duct. This was a fairly unsophisticated demonstration, very much home made and low tech.

In the same article, more sophisticated experiments regarding Russian freighters running on rivers were mentioned. The Russians were reportedly injecting the exhaust under the freighter hulls and achieving some increase in effiency. There were no details of the Russian experiments other than the report they had done it.

Once again I mention that I may have completey misunderstood the premise of this thread, and if so, look forward to being set straight by the collective wisdom of our assembled panel.

[mmd]

Tom, what type of more objective testing and reporting would you like? The boat in the photo above is a shallow-vee planing hull form terminating in a flat after section bounded by rails, into which an air stream is introduced to reduce skin friction in the after part of the hull. Top speed of the hull exceeded calculated expectations for a non-ventilated hull by approximately 20%. I thought it a rather successful real-world demonstration of the principle. Too bad we didn't have an additional half-million dollars to build a similar conventional hull as a trial horse, I guess.

[CDK]

Golly, I'd think you'd need a pump capable of moving like a thousand cubic feet of air a minute to see any real improvement. I might be mistaken but wouldn't you need like eight times the air when your speed doubled, following the ccube function rule of thumb for horsepower? Or is that only in air and in a denser medium you'd need correspondingly more? Dunno.

No, all that is needed is a very thin air layer. Of course the output must increase with speed to obtain the same thickness but that need not be the objective. Too much air would cause the hull to loose its grip and behave like a hovercraft.
That's the way I think it is, but I have NOT yet tried it.

[tom28571]

Tom, what type of more objective testing and reporting would you like? The boat in the photo above is a shallow-vee planing hull form terminating in a flat after section bounded by rails, into which an air stream is introduced to reduce skin friction in the after part of the hull. Top speed of the hull exceeded calculated expectations for a non-ventilated hull by approximately 20%. I thought it a rather successful real-world demonstration of the principle. Too bad we didn't have an additional half-million dollars to build a similar conventional hull as a trial horse, I guess.

Well Michael, some experts claim that air entrained water under the hull decreases drag and some say that it increases drag. I have read these claims but can't direct you to them. The boat in your example gave results with injected air but no performance data without the air. I don't think you would buy that without further data and I don't either. Your reply adds some information that would have helped (the 20%), but it's still calculation, not demonstrated. I don't have a dog in this fight, I'm just interested.

As I said, the material in the links above looks interesting and seems to support lower drag for injected air under a flat plate. I don't have the time, money or expertise to work on this myself and will just wait to see what falls out.

[mmd]

As stated, we didn't have the money to build a trial horse. However, with previous boats built with similar hull forms in varying sizes from 28 to 60 feet LOA, the accumulated trials data was used to refine our in-house hull speed prediction program to the point where we were confident of our velocity prediction to within a knot or less. The Ocean Mist shattered those predictions with a vengance, with no other variables other than hull afterbody form (which should have created drag rather than reduce it) and air injection along the planing surface. We didn't investigate further because the client was happy and we were in the business of building boats, not doing academic research on them. I have no better proof available other than a successful build.

[tinhorn]

Found this while I was searching for something else:

[rwatson]

with no other variables other than hull afterbody form (which should have created drag rather than reduce it) .

Now the the other variables start surfacing!

How simple would have been to turn the air bubbles off and record the "non aired" performance?

Record the average speed on GPS for 10 minutes, average speed on GPS without bubbles for 10 minutes - keep that up for an hour, and you should see a healthy trend despite variance in winds.

If I was an owner, and I had spent money on the innovation, that would be the first thing I would have done! If I was the designer it would have been top priority for me!

[tom28571]

Now the the other variables start surfacing!

How simple would have been to turn the air bubbles off and record the "non aired" performance?

Record the average speed on GPS for 10 minutes, average speed on GPS without bubbles for 10 minutes - keep that up for an hour, and you should see a healthy trend despite variance in winds.

If I was an owner, and I had spent money on the innovation, that would be the first thing I would have done! If I was the designer it would have been top priority for me!

My argument exactly. Michael, I have no problem with your work. Quite the contrary as you have showed some impressive designs and always have good thoughts or advice for us amateurs and designer wanabes. Maybe it's because some guy was just trying to send $2,000,000 if I would only advance him $2500 for some expenses.

[rambat]

MMD, How much did the Ocean Mist weigh? Also I think Tom is confusing trapped bottom bubbles with aerated or frothy water. Anything, including air-bubbles (pressurized not cavitation) which displaces water between the hull bottom and the surrounding fluid will raise the hull equal to its own displacement. If that was not true a hovercraft would create a very deep hole in the water in defiance of physics.

[mmd]

Ocean Mist's air-induction system was not pressurized nor one that could be "turned off". It was an atmospheric system, controlled slightly by a damper in the ventilation duct, that relied on a pressure differential of the water flow along the hull (cavitation in the sub-transom) to draw air into the slipstream. And, yes, we did do a series of trials at varying amounts of damping of the air ingress and at varying speeds and sea states.

C'mon, guys, think about what you are asking... Do you really think that I built a large, expensive boat with a novel hull feature and did not do as complete a program of evaluation trials as I was able to? They were not as controlled nor as exhaustive as I would have liked due to time constraints and client demands, so I didn't publish a technical paper on the hull, but I didn't just build it and send it on it's way. I do have a pretty extensive amount of data on the performance of the hull; enough to convince me of the efficacy of the concept within certain limitations. Enough, also, to convince me to not make every detail public, either. <wink, smile> To paraphrase my esteemed colleague and fellow forumite John Hardiman's byline, "The only thing a naval architect has of value is his data base", and that is not to be given away freely.

Her full-load displacement was approximately 18 long tons.

[BMcF]

Positively ventilated steps in planning hulls have been successfully implemented on many craft. The Russians were heavily in to 'air lubrication', even for non-planing hull types. We have worked with several designs over the last 20 or so years, and the results for the air-lubricated non-planing or semi-planing vessels were routinely diappointing. But the benefits for a planing monohull have been proven.

There is (or used to be) a monohull crew boat working out of Jacksonville, Fl that was retrofitted with a ventilated step and the blowers to force air through it. With no change in the powering (DDA 12-71s IIRC), the top speed was increased from roughly 28 knots to 34-35 knots. Unfortunately, I cannot lay hands on my notes about what the air-HP requirement was...I do recall that there was a common 'plenum' built over the step and used roots blowers bolted to it, end to end, to provide the air.

[Village_Idiot]

I mentioned this in another thread a while back, but here goes again.

Back around 1993, the science journal Nature had an article on hydrodynamic flow. The researchers were testing the speed of water through a pipe or sluice and found that random projections on the inner surface of the pipe increased the water velocity something on the order of 15%. Uniform projections increased water velocity minimally, perhaps insignificantly. They summarized that the real key was that the projections had to be random.

The theory behind the projections was that with a smooth surface, water flowing next to the surface was slowed down by friction against the surface. This slower-moving water would tend to "roll up" much like you would roll up a rug, and create large vortices. Once the vortices became large enough, they would break away from the surface and into the more mainstream water flow. The "breaking away" action is what caused turbulence and slowed overall water velocity. By adding the protrusions on the surface, the vortices were broken up before they got very large, thus improving overall laminar flow adjacent to the surface.

Take-home message: For hull design, you won't get laminar flow right at the surface, no matter how slick. The trick is in controlling laminar flow just a few mm away from the surface to enhance overall flow. Random protrusions seem to be a good start at doing this.

[TollyWally]

"Take-home message: For hull design, you won't get laminar flow right at the surface, no matter how slick. The trick is in controlling laminar flow just a few mm away from the surface to enhance overall flow. Random protrusions seem to be a good start at doing this."

Is this similar to the sharkskin "rougher is faster" idea?

[Fanie]

I haven't read all the posts in detail. The simplest way of 'air' injection would probably be achieved using the hull. My power boat has a semi cathedral hull. At low speed the outer hulshapes pushes the water towards the centre hull, so it gets on the plane faster and easier. I'm sure air forced under the hull does make some difference, but considering the boat's weight and the inefficient shape for tunneling air under the hull this would have a neglectable difference.

If you want to add air into the water / hull part you either have to go much faster than what I can go, or have something that induces air into the water (bubbles) just before the planing area. Keep in mind that this creates another set of problems, props like solid bubble-less water to bite in, otherwise the prop starts to cavitate and you lose more than you gain.

Maybe a wabble front in the hull planing area could cause water surface disturbances, as long as the drag it creates is less than the gained less friction.

If you're looking for pushing air between the hull and the water surface, I guess you're looking for a hovercraft... ?

If you're after more speed, just maybe one could pay better attention to the planing area shape of a hull - there may be something there yet, but I'm no expert on that. Something like a twin shallow hydrofoil as mentioned somewhere previous that would take over the planing area at a certain speed.

[tom28571]

MMD, How much did the Ocean Mist weigh? Also I think Tom is confusing trapped bottom bubbles with aerated or frothy water. Anything, including air-bubbles (pressurized not cavitation) which displaces water between the hull bottom and the surrounding fluid will raise the hull equal to its own displacement. If that was not true a hovercraft would create a very deep hole in the water in defiance of physics.

I don't think so, but there is obviously a lot more to be learned here than can be taught by a simple yes or no answer. I think hovercraft are supported by two forces and neither is air bubbles. Unless the air under the skirt of a hovercraft is equal to or less than(not) the pressure outside the skirt, there must exist a hole in the water. Not enough to support the craft, but some. This is off-topic anyway.

[AmnonMikeCohen]

As to marine application of the idea, there are many marine vessels already using this idea, and if you search Google Images for Surface Effect you should see much of what is already there.

The WIG (Wind In Ground) Effect, is actually applicable to Seaplanes and not to Boats and Ships - as it is in our focused interests!

The best I have found, which has less problem in open seas - of the air leaking out from under the hulls, is The Norwegian Skjold Surface Effect watercraft.

There is a lot to gain by employing the concept, but only my invention goes where no one has yet been able to develop, but it is still useless for you and our readers, as I am keeping it as a highly valued trade-secret and am only working on the water-lubrication layer part of my multi-lubrication surface effects hulls; an advantage which can be added to all existing hulls already.

The tests show 30% increase efficiency by air injection, and there are other lubricants' options developed which are economic for use - but the extra power for air-injection is needed and must be added plus installed on a boat or ship to be effective.
It is a good idea, and is in use, but the USA Navy has not yet mastered the capabilities in a way which is very economically beneficial, while ignoring my development because I am not willing to be dishonest with the USA taxpayers who subsidized my scholarship education, many years ago, and which is why I want the benefit to be honestly in the best interests of the American people.

:idea: Here is where you may find, the American model of the invention, published in 1996 It unfortunately has The Leaking Air problem...
http://http://www.google.com/patents?id=3VQlAAAAEBAJ&printsec=abstract&zoom=4&dq=surface+effect

Please do not hesitate to ask for more information, here or directly, from developers and owners of this knowhow.

[CDK]

mmd's "Ocean Mist" gained 20% speed with just a clever hull design to introduce air in the boundary layer. No blowers, ducts, valves or plenum that might be considered as negative factors for reliability. Yet it didn't start a hull design revolution.
I bet that if a passenger car manufacturer found a simple way to improve fuel efficiency by 20% the whole industry would follow immediately. History shows that even a not so simple improvement like overhead cams, 4 valves per cylinder and common rail injection was rapidly accepted and became general practice. Felix Wankel's rotary engine was an exception, but that had to do with patent rights and the making the whole existing engine industry obsolete.

Why there is so much conservatism in the boating industry I can only guess. Maybe because the disciplines of hull design and propulsion each follow their own path or because the volumes simply aren't large enough. And it is of course much simpler to install a larger engine when more speed is required.

rwatson's suggestion to do a scale model experiment is tempting, but it would be tough to measure differences in speed, find a pond without waves etc. And you all would not be impressed if I would report that my air injected toy boat ran 15 minutes on a battery charge instead of 10.
But there are some derelict fishing boats nearby and I happen to have a garden blower I never use because it is so noisy.....

Village_Idiot, the information about random projections is not correct. A hull with a lot of barnacles is slower than a clean, waxed one.
I once shortly worked in Martonair's laboratory where I developed an empirical formula to predict the flow capacity of compressed air through a tube, based on pressure, tube length and diameter. Any obstacle that causes turbulence reduces the output, even fittings that did not reduce the diameter but had a gap between tube ends.
It was a pneumatics company, so they were not interested in liquids.

[AmnonMikeCohen]

You are right, Fanie:
If you look for the MSHIP design, you will see information supporting and explaining what you already have and what they are doing in this Marine Art.
See it @ http://www.mshipco.com/mship/wrapper.php?page=tech.html


I haven't read all the posts in detail. The simplest way of 'air' injection would probably be achieved using the hull. My power boat has a semi cathedral hull. At low speed the outer hulshapes pushes the water towards the centre hull, so it gets on the plane faster and easier. I'm sure air forced under the hull does make some difference, but considering the boat's weight and the inefficient shape for tunneling air under the hull this would have a neglectable difference.

If you want to add air into the water / hull part you either have to go much faster than what I can go, or have something that induces air into the water (bubbles) just before the planing area. Keep in mind that this creates another set of problems, props like solid bubble-less water to bite in, otherwise the prop starts to cavitate and you lose more than you gain.

Maybe a wabble front in the hull planing area could cause water surface disturbances, as long as the drag it creates is less than the gained less friction.

If you're looking for pushing air between the hull and the water surface, I guess you're looking for a hovercraft... ?

If you're after more speed, just maybe one could pay better attention to the planing area shape of a hull - there may be something there yet, but I'm no expert on that. Something like a twin shallow hydrofoil as mentioned somewhere previous that would take over the planing area at a certain speed.

[kach22i]

http://www.google.com/patents?id=3VQlAAAAEBAJ&printsec=abstract&zoom=4&dq=surface+effect

I know this one (SeaCoaster), have been told it's a "dead-end".

http://www.seacoaster.com/Air-Assisted_Catamaran_Concepts/index.htm


And there is this..........

http://www.dkgroup.dk/

[charmc]

This article from New Scientist (Feb 2006) gives a good overview of research and protypes so far, including mention of the practical problems inherent in scaling up from tow tank test models, as well as discussion of the supercavitation tests which have seen torpedoes travel at more than 100 knots fully submerged.

http://technology.newscientist.com/article/mg18925391.600

[erik818]

The fan needed to inject air doesn't have to be very complicated. I tried a conventional dust-collector fan (actually the cheepest one I could find in the cheepest store in my area). It provides enough pressure for the purpose of helping the ventilation of a stepped hull.
My fan has the capacity of 15 cubic meters/minute. A slightly more expensive one, with a 2 kW motor, has the capacity of 45 cubic meters/minute (1500 cubic feet/minute) so feeding the step with enough air isn't a problem. I don't know at which pressure the flow was defined.

I don't have any results to add to the discussion, as my contraption had too many other problems. The fan worked however, and the bubbles were impressive. (And of course the boat didn't sink, i rose a few cm.) Next time I hope to do it better.

I think that the hull shape needed to trap the air used for lubrication gives properties that are considered negative from other market aspects. A deep V bottom wouldn't work.

Erik

[Village_Idiot]

[quote]
"Take-home message: For hull design, you won't get laminar flow right at the surface, no matter how slick. The trick is in controlling laminar flow just a few mm away from the surface to enhance overall flow. Random protrusions seem to be a good start at doing this."

Is this similar to the sharkskin "rougher is faster" idea?
[quote]

Yes, I believe that is what led the researchers to examine the concept further. It's been nearly 15 years since I read it, so don't recall all of the details.

[quote]
If you want to add air into the water / hull part you either have to go much faster than what I can go, or have something that induces air into the water (bubbles) just before the planing area. Keep in mind that this creates another set of problems, props like solid bubble-less water to bite in, otherwise the prop starts to cavitate and you lose more than you gain.
[quote]

There are some folks (mostly southern U.S. duckhunters) who introduce water into the prop stream via a vent in a tunnel (pocket) hull. They use heavily-cupped props with large blade surface area to cope with the ventilated water - it actually improves their performance (time to plane, top speed, etc.) over using a non-vented tunnel. Some use a semi-cleaver design, or some variation of a surface-piercing prop.

Bill Allison in Rosenberg, TX makes a fishing boat that you might classify as surface-effect. He calls it a catamaran, but it is really more of a hybrid planing cat / tunnel hull. The hull is designed to force water up into the tunnel and allow the prop to run and work above the surrounding water level, so that the only thing below the hull of the boat is part of the motor skeg. Sounds unbelievable, but there are many on coastal fishing forums who will attest to its shallow-water performance [check out http://2coolfishing.com/ttmbforum/search.php?searchid=2970895 ].

[quote]
Village_Idiot, the information about random projections is not correct. A hull with a lot of barnacles is slower than a clean, waxed one.
I once shortly worked in Martonair's laboratory where I developed an empirical formula to predict the flow capacity of compressed air through a tube, based on pressure, tube length and diameter. Any obstacle that causes turbulence reduces the output, even fittings that did not reduce the diameter but had a gap between tube ends.
It was a pneumatics company, so they were not interested in liquids.
[quote]

Maybe the barnacles were too closely spaced, or not the right shape? I don't recall the shape of protrusions that they used (was a long time ago). I also don't recall the size of the protrusions relative to the size of the vessel. If someone has access to a library with a large archive of periodicals, they could look up the article.

Such an experiment probably wouldn't be too difficult to design.
1) Set up a reservoir drained via a near-horizontal half-pipe sluice.
2) Swap out different sluices lined with various-sized protrusions.
3) Record time it takes for the reservoir to drain with each sluice.
OR
4) float a neutrally-buoyant object through the sluice and record time/distance.

Please don't take my word for it - find the article or do the experiment. I just brought it up to add to the discussion. I have no dog in this fight. :p

[AmnonMikeCohen]

Thanks George, these http://www.dkgroup.dk/ are closer to my invention, but mine is yet more advanced solution which offers more internal room inside the hulls for cargo or personal use for owners, which are important values to owners; and furthermore, my hulls employ my Water Lubrication layer which by itself is more efficient then the 15% they say come with the additional lubrication while not saying how much more power is being used (I'll try to get this information from them, if they answer me) and also please note, my invention also has an option of reduced pollution as well, so I am still ahead but it is unfortunately still only in my head and my corporate records - and not yet on the market which need good advanced inventions.

:!: Lets hope we see good news, and thanks for sharing this good DK GROUP work in the art of better and more economic sailings of big ships

Respectfully and thankfully yours, Amnon Ami Cohen

[rasorinc]

This is probably not of any assistance but don't we have a very high speed torpedo that moves within an envelope of air ? (a bubble)

[AmnonMikeCohen]

Under the surface travel is not like traveling on the surface, as under the water travel is more like traveling in air to space, with water pressures which are much higher the in atmospheric air and the vacume of space itself.
Russia had worked on this technology, and I am not sure where the USA is on this art, which is good for Submarines as well as Torpedoes.

You basically have water and special lubrications options you can pack into a torpedo or a submarine, but air (compressed) is too dear for such use, and can be good for short term as in short distances only.

[rambat]

I ran a quick calculation and the 20% gain is not proven for the "Ocean Mist" As I am not the only one on this forum with a horsepower to weight, speed prediction program this is offered for comparison. I show that a craft of the weight and horsepower stated would go 27.6 knots conventionally propelled, and 30.4 Knots with surface drives. Both of those predictions are at full load and boats are seldom run for speed trials at full load. I have grown skeptical of most air-film enhanced hulls. I think like any beneficial technology if it were real after the last 127 years since John Thorneycroft discovered it, it would be in widespread use. But I am not here to cast dispersions at inventive ideas, just wish we had something new to check out.
I think the concept for a air-lubricated hull breaks down in practice when the "film" separates upon contact with the bottom flow, its not like a cohesive sheet and tank video often shows the air "film" streaking into tendrils, wetting the supposed lubricated surface. In spite of this I am a big proponent of SES's and ACV's as they ride on a true air-bottomed hull, most of the time clear of hard contact with the wave tops. And Tom was right IMHO, a cavity sucking air is also likely to suck the hull lower in the water. Also a ACV pushes a depression in the water while at rest but on cushion as if it was a displacement hull, it crawls over that depression or Hump as its known when it starts going too fast for the viscous water to move out from under it, then its planning on its air cushion. The first program I ever wrote was to calculate the depth of water displaced by a SES when on cushion while at rest.

[tom28571]

Rambat,

Did you look at the proportion of the hovercraft weight supported by the air cushion (pressure) versus the amount supported by the thrust of the fans? The former is bound to cause a depression in the water. I would think the depression gets shallower at speed because of the time element.

This would be similar to waves from a speeding planing boat getting smaller than at low speed. That is, the dynamic force supporting the boat must be the same at all speeds but the waves created at high speed are spread out over a larger portion of water, making them of smaller height. Total energy in the waves remaining the same.

[kach22i]

I would think the depression gets shallower at speed because of the time element.
Correct.

[mmd]

The issue with Ocean Mist that made me hesitate to yell about it from the mountaintops was that the entrained air "lubrication" was difficult to maintain in a seaway. Worked great in sea state 0 to 3 or 4 (depending on wave period and form), but failed after that. Since this particular boat worked in the northern trade winds where sea states were normally 4 to 6, it was operationally a failure. In different ambient conditions, such as a sheltered bay or river, it would be a good concept. I'm just waiting for the right commission to come along to ressurect the idea...

[rambat]

Its Mardi Gras down here so that may be why I dont understand the dynamic vs Thrust issue, its also tooo bright right now, must find ....a dark bar to shield my bloodshot ....eyes

[AmnonMikeCohen]

Air Injection, will leak out if A SKIRT or The HULL can not keep it in the open seaway - and this is its real challenge - as it can grant up to 30% increased efficiency from what I have been told.

[kach22i]

FYI:
Some projects I just found, worth looking at if interested in this topic.

http://www.seseu.com/R&D%20folder/randd.html
http://www.seseu.com/R&D%20folder/Bilder%20monoCat%20model/MonoCat%20model%20in%20the%20water.gif
http://www.seseu.com/R&D%20folder/Bilder%20EFFISES%20partners/EFFISES%20partners%20in%20Athen.jpg
http://www.seseu.com/R&D%20folder/Bilder%20ASV%2027%20Medium%20Lift%20LC/ASV%2027%20ML%20LC%20Westcoast%20of%20Norway.jpg
http://www.seseu.com/R&D%20folder/Bilder%20E%20125%20-%209%20m/E%20125%209%20m%2060%20kn%20.jpg

[AmnonMikeCohen]

Thank you, very much George, again; I have heard about this project, so thanks for spotting it for me - - but as you may and can see from my more primitive pictures resulted from poor funding, my invention is well ahead of them, as they still have a wake next to the hull (The hull is still Plowing, even it being sharper to cut through the water) and have not climbed "The Hump" of the Bow-wave my invention cancels along with the Skin Friction and Drag which have been virtually eliminated by my invented FINS, achieving this, even without my Secured Air Cavity which is also included in my inventions, as in my registered application in April 1991.
Yet, this is who should call or contact or respect my work and invite me into the project Europe or America, so we can offer everyone what I can not do alone, as a privately funded successful and honest inventor.

I wonder how can I get these good guys to contact me for my help to the positive evolution of our maritime industry

FYI:
Some projects I just found, worth looking at if interested in this topic.

http://www.seseu.com/R&D%20folder/randd.html
http://www.seseu.com/R&D%20folder/Bilder%20monoCat%20model/MonoCat%20model%20in%20the%20water.gif
http://www.seseu.com/R&D%20folder/Bilder%20EFFISES%20partners/EFFISES%20partners%20in%20Athen.jpg
http://www.seseu.com/R&D%20folder/Bilder%20ASV%2027%20Medium%20Lift%20LC/ASV%2027%20ML%20LC%20Westcoast%20of%20Norway.jpg
http://www.seseu.com/R&D%20folder/Bilder%20E%20125%20-%209%20m/E%20125%209%20m%2060%20kn%20.jpg

[rwatson]

"I wonder how I can get these good guys to ...."

Hi Amnon

I have been following your contributions with interest, and I do hope you have a successfull technology there, that will be of value to the marine industry.

May I comment in a constructive manner without wanting to be unkind at all.
I dont think I am in a position or be an investor or whatever it is you are seeking, but my observation is that your presentation of information could do with a bit of polishing from a competant English speaking technical public relations person.

While you are listed as being based in Canada, I gather that english is not your first language. The letters you write and your website give me the same feeling as those emails we get from someone in Kenya who wants to send me 3 million dollars and will give me 25%, in other words, they dont inspire confidence in any business dealings.

From my experience, this appearance in written and web publication, together with your enthusiastic claims, is likely to discourage serious businessmen from approaching you to talk about business opportunities.
As I say, I am not saying this to be unkind or critical, but as a contribution to your effort.

I do hope my suggestion isnt at all offensive, and I hope it will help you achieve all the success you deserve. I know it can be difficult to share ideas and research secrets with other people, but I do think you need to approach english speaking clients with a more inspiring standard of communication if you want to achieve good results.

Good Luck with all your efforts.

[AmnonMikeCohen]

NO WE ARE NOT FROM KENYA & I AM NOT OFFERING SOMETHING I DO NOT HAVE!

1st) English is not a language I shall ever master, as it has to evolve to my clearer thinking in another, yet older natural language.
2nd) My reply to what many already had shared as you do, in good spirit indeed and as you state, is that "we throw the package the gifts come in, as we keep just the gifts we like to keep", so my gift is presented unwrapped and not made attractive to attract an investor, or to catch a fly (From Kenya), but my gift is to interest a mariner who like myself wishes to take the industry into its next future evolution which is in harmony with ecology (Not much market value there, except in Europe) as well as bring us money and profits and thanks plus respect.

Now up here in Canada, noting you are there under (On Top if you see it from your sky) we believe we can teach the Australians some new technologies your champs had not yet devised, while you do hold a real big share of advanced designs and winnings on open waters - so please accept my respects in my hope for fair-play from your good people!

I do thank you for your writing as you have put me into a good mood, in the cold winter we are having - and I wish I was there now, in the sun with you good people.

(Please note, Philip at INCAT did not choose to respect my original input into the now DEAD Pacificats which were constructed for our British Columbia Ferries, and my invention was and still is the only savior of these 3 cat's...)

[rwatson]

Hi Ammon

Its good that you have no problem understanding english TO you, and I think I understand the English FROM you enough to continue the conversation (if I read it a couple of times ).

I, and perhaps others may be puzzled about how you wish to proceed. I got the impression from previous posts that you are not rich enough to fully patent and develop the product, but you are very wary about divulging any of the details, of course.
I see your situation as a problem, for the following reasons
1) If someone builds a boat using your invention, they will have the method.
2) If you consult in the design of a boat, they will have the method
3) If you provide enough info to someone who wants to pay for a licence, they have the method
4) If you get paid to educate people on the technology, they have the method

I am puzzled about how you want to proceed with your "product" development. I am sure there will be very few people who will offer any type of financial support until they get a lot more detail.

How is it that you plan to proceed ?

Cheers

Ray

[AmnonMikeCohen]

My humble website includes my proposed Executive Summary of my Business strategy plan, which is found @ http://www.SuperiorHulls.com/SHIBusinessStrategyPlan.html and there is also a 55 page Business Plan for the project, in a PDF document.

I like these, to attract the person who will meet my commitment and we then simply go ahead with a plan we agree on, as I expect the partner or investor, to have some new and other contributing positive input, as well as be already knowledgeable about the industry and option we may have, and expect him/her/them in some way to be already connected or active within the industry, with a team a company a facility, ideas and options - or even it may be a mariner who just love to take the project to the next step.
As soon as we can be showing and demonstrating and publishing plus starting to be serving my existing clients and also initiating the marketing of the products and services we can offer, which are related to the yet new invention, everyone will know the basic way these Fins are attached to a hull, and how these work, and we then will be having to be more focused on sharing all the knowhow with the world, so boat owners and ship owners can gain the benefits I am writing about and claiming as safe and beneficial, and these will be boats' and ships' owners who will choose to trust the technology and our ability to service its secured use. (There is some homework related to patent and insurance issues I have in place to be implemented as well, and not only the new business development initiative I believe you are asking about.)

It is the Opening of the door for business that is the only holdup I have, as I see it, and it will be derived first by the trust and interest of the proper person, and then-after by our way of protecting our incorporated interests in serving the vast open markets worldwide and protecting our clients from obtaining the wrong products which will not be licensed for safe use, so that only the proper product is installed on each boat or ship or a class of watercrafts - and this, I expect will be our key focus, from the time we open for business and will be sharing our knowhow with the mariners who like our products and services. (By employing a new impressive website, and opening a global business office etc...)
There will be efforts for Racing and Advertising, gathering Testimonials from our clients and verifying the facts as to improved performance and economy on many vessels and not only on our sets and demonstration boats, and there will be news making, and publishing articles in key selected professional publications, and I already have in place the ideas of following the standard way we shall have to "Fight our way to success and recognition" within the Maritime Industry, on International Basis, from our staring point.

believe me, I like it to be known, but can not prostitute the technology to the wild markets, as it will end up sick and unfit for future use, without the inside knowhow of the simple looking invention, and its real promising future designed hulls.

I hope this is not only a plan or a personal dream, because it is not much fun to have the only fun boat in the world which fly by the power of a marine engine!

[intrepid71]

[QUOTE=kach22i;183350]I know this one (SeaCoaster), have been told it's a "dead-end".

http://www.seacoaster.com/Air-Assisted_Catamaran_Concepts/index.htm



I remember reading articles on the Seacoaster a number of years ago and it sounded pretty promising. I take it they didn't get good results from the full scale prototype they built for the Navy. Do you have any details on what didn't work?

[kach22i]

[QUOTE=kach22i;183350]Do you have any details on what didn't work?
The information about this was "an opinion" posted by another forum member who was maybe working on a competing craft. However, I'm taking his word for it as I've found his posts to be very informative and respect his professional credentials.

I have seen so called "dead-ends" produce some fruit, but so expensive and of such a narrow operating envelope that only the US military can afford to use it. The Osprey tilt-rotor comes to mind as an example.

[juiceclark]

I've looked at hundreds of private equity financings of new projects over the last 20 years. The ones to be wary of are the grand inventions that will change an industry...all with few details. The best was a metal shredder in Mexico for CA autos - hardly genius.
Hey Cohen, do you want me to link you to a few good Venture Capital firms? BoatDesign.net is an awesome site for brainstorming design ideas, but we all are quite curious why you would try to sell an idea here? If there is anywhere your idea is likely to be stolen it is right here. Moreover, this is the most skeptical group your idea will face.
Find potential investors, qualify them and sell them. Mitt Romney was a great private equity financier...and I just heard he now has some free time.

Tony in Sw FL

[CDK]

Dear AmmonMikeCohen,

I started this topic because I do not want to invent a wheel that will not turn, so I am interested in success and failures from other people.
Turning the boating world upside down or even starting a business is not my objective. I passed that line long ago and am only interested in pursuing some old ideas I could not find the time for when I was president of an electronics company.
Before drilling holes in my boat's hull I want to learn as much as possible about similar experiments.

From you I learn nothing.

Your website looks like the Christmas tree in a Chinese restaurant: it hurts the eye, yet has nothing to offer but unsubstantiated claims. In my wild days a owned a Glastron-Carlson CV23 and let my wife take pictures while running over choppy water at 65 knots. Just the Mercruiser tail in the water, no hull contact, no friction. That would look great on your website, wouldn't it?
Look at my posts "Marinising VW turbo diesel engines" and "DIY tunnel drives". I have nothing to hide, feel free to use any idea you may find there.

[AmnonMikeCohen]

;) TONY, thanks for your help and frankness, but it is first my intent to bring the news about my successful work to this group, as they/we are committed to good and new marine designs, and to helping information flows and sharing plus help, and many if not few, do know people who may benefit from knowing about the opportunity to bring advancement to the industry and profiting or benefiting from it.
My second intent, is to locate the proper partner or investor, so I can post and share more and all my news, and not keep it under The HOOD, as it will be frustrating to us all, if it does not come about sooner then later.

:!: Now I do not know Mitt Romney and if he is a mariner, but if you do, please let me know.

I already have met and shared information with members, privately also, as far as Italy and Norway about the opportunity for a factory, shipyard or designer to capture the interests of a client as well to create the first one with the FINS on or with The Hull.

I also found most people are not Pirates, and this is a good membership of sailors and designers, novice and readers who care to know, old-timers, masters and so many good people, most are very helpful and like to see new technologies come to light, so I do trust this group of people, and hope you also accept my positive experience, as a very cautious inventor who is wise about not loosing his life's work by giving it away in a foolish way.

:confused: Looking forward to having Mitt Romney contact me or how to contact him - if he is a good man for the Maritime Industry.

Best regards to your BIG project I see in your gallery...

[AmnonMikeCohen]

The original invention, was just that, it was an invention on paper and not a result of a study of a concept or idea, and they found out the expensive disappointing way many go by, the flaws of the design, which was and still is to its copiers, LEAKING of Injected Air, in open seas that are not calm like a swimming-pool.

Please take note, that you can legally register an idea or concept - without any facts or relationship to life, nature, reality, markets, needs and so on. It is like writing a poem, a song, a story etc'. It can be classified as NEW ART, but as most inventions, no value! no use! no interest! no hope!!!

What you want to protect, is A Discovery with new science and value which is wanted and safe and increases the quality of life, something people will pay for and use, that you can put as a new Intellectual Property, and be the First to Invent, First to File and hopefully first to find the needed backing so you can share it with the world and not die a bitter disappointed person!

If you have noticed, my Superior Surface Effect includes first A Water Lubrication Layer as well as a Secured Injection Cavity - now this should get the brain working to figure out why I must protect it as I do, while telling you what it is without making it visible - that is sharing and not hiding.

My original potential partners, have developed the technology you are interested in, but the MID FOIL (Google for it) is theirs contribution that I respect, as it is in harmony with Archimedes as well as with Foil Technologies! They are good people also, located in Hawaii.

Ami


[QUOTE=kach22i;183350]I know this one (SeaCoaster), have been told it's a "dead-end".

http://www.seacoaster.com/Air-Assisted_Catamaran_Concepts/index.htm



I remember reading articles on the Seacoaster a number of years ago and it sounded pretty promising. I take it they didn't get good results from the full scale prototype they built for the Navy. Do you have any details on what didn't work?

[AmnonMikeCohen]

This patent, remind me of the original Jet Propultion concept, which we now know as a very viable technology, but the original was a pump moving the water and the water was moving the boat as a reaction to the flow into the seaway behind the boat.
:idea: Old inventions are real gems!
Ami
Found this while I was searching for something else:

[tuantom]

Anmon,
I've read this thread and looked at your website. While your motivation and persistence is impressive, I can't help wondering if medication might somehow play a central role in your business plans.

[kach22i]

Anmon,
I've read this thread and looked at your website. While your motivation and persistence is impressive, I can't help wondering if medication might somehow play a central role in your business plans.
He does get carried away;)

Not to hi-jack the thread, but from what I've read about SES, this hull should perform well even without air assistance or other gimicks.

http://www.catamarans.com/news/2006/04/CatComparison.asp
http://www.catamarans.com/images/news/2006/04/Fig_4.jpg

I love gimicks, but I also like to think that I'm developing an eye for what works. SES's work, hydrofoils work, hovercraft, cats...........and even plain old boats.:p

[AmnonMikeCohen]

This is just so you know, one can not achieve what I have, if one needs medication - because one needs all faculties in top order when experimenting or deriving proper conclusions.
I am Yisraeli born and raised, and our language is logical and natural, and helps us capture truth and facts, and as a spiritually very respectful person I keep serving the truth at all times; and this is like a gift, because my English will never save me, being the best political language that I know, and it always helps us all if pictures and sounds are added to facts in writing.
Trust, is a problem many people have with the truth I represent, so you are not alone and not the first to mistrust real truth you read in my poor English.

As a boater, and since I am in the security business, beer (Canadian) is the only medication I take, if I eat not Kasher (Kosher) food, just to help save my good health and younger look I still have.

The only wild thing I like, is speed on water, as on land, it is not safe - so I drive my Bonneville just over the speed limit so to keep the turbo-charger in higher the idling speed on the highway - and keep changing the oil more then required by the manufacturer.

My test boat, is not dangerous to take for a spin, and the SeaDoo is not in use now, so my water speeds are below 40 and very safe to play, even though it is safe to drink and drive with the fins installed on a boat...

Anmon,
I've read this thread and looked at your website. While your motivation and persistence is impressive, I can't help wondering if medication might somehow play a central role in your business plans.

[tuantom]

I imagine you mean "proper conclusions" in a subjective way.
As far as I can see, you haven't accomplished anything other than to go on and on and on about nothing in a language that dulls your mind - and to put a bunch of nonsense on a free website. Does your business plan state that even you won't invest any money in your "invention?" At first I thought you were just amusing yourself to see how far you could string this along; I'm beginning to think you may actually believe what your saying - Odd. Anyway I'm done wasting time on this. Play safe and over-medicate whenever possible.

- Tom Rohe

[rwatson]

This is the business plan from the web site -
"INVESTMENT OPPORTUNITY: "SUPERIOR HULLS INC." is seeking between US$175,000-$300,000-$475,000-$750,000 USD working capital to enter the industry and market its new advantageous product line, and may need further capital to secure its new corporate market share, after obtaining a successful stronghold presence within the industry."

So I imagine they will be happy to take any significant amount off some starry eyed investor, from $175 to 3/4 mill - anything will do. Lets not be tied to any firmly costed development schedule here in the "advantageous product line" until they get a "successful stronghold presence ".
I would have to get an english translation to figure out all the small print - imagine if the proposal and contract were worded personally by Amnon!!!!

[SaltOntheBrain]

This is a reply to the Air Lubricated Hull portion of this thread, not the hijacked portion.

There was a boat on St. John, USVI called "Caribe Air Ride". It was owned by Transportation Services. That boat had a large compressor which pumped air through holes in the outher layer of a double hull. It worked great in protected water, but not in heavy chop. The hull was cut out, the pumps removed and a single, conventional hull put in.

About 30-40 years ago, a small workboat out of Port Aransas, Texas used an auxilliary engine driving two 6-71 superchargers as compressors and upped his top speed from 21 to 31 knots by injecting the air through a small step glassed in at the front of the planing surface. I don't know how his fuel consumption was affected by the extra engine, but his speed came up nearly 50% even with the extra weight.

In controlled conditions, air lubrication can be made to perform very well, they just always seem to have the controlled conditions turned off when I get a chance to go boating.

Lance

[AmnonMikeCohen]

If you were A Businessman, in the development industry; you will understand the optional business strategies flexibility as a superior quality investment opportunity on a technological monopoly ownership; so your again trying to be pocking holes in the solid short-form of the 55 page business strategy plan, clearly demonstrate you are not at all familiar with sophisticated and winning Business Strategies Plans, and are reacting like a kid who believes he found a flaw in the work that someone smarter then he is has developed.

So as others say here, get off your negative thinking appeasing the many other negative self fooling members who are so vocal without respect to truth and facts I sure will not share with such negative people, as too many of you are obviously and simply a None believers group who has never invented something of value, and are not qualified to criticize my honest wise work, by claiming to be professional or using professional terminology instead of simple English for all people to understand and know.

Sorry there are more fools then respectful members responding to my positive and honest thread - as you have made it look as negative as your thinking is, distorting what the thread really is and has to offer, for the dissent mariners I am looking for.

This is the business plan from the web site -
"INVESTMENT OPPORTUNITY: "SUPERIOR HULLS INC." is seeking between US$175,000-$300,000-$475,000-$750,000 USD working capital to enter the industry and market its new advantageous product line, and may need further capital to secure its new corporate market share, after obtaining a successful stronghold presence within the industry."

So I imagine they will be happy to take any significant amount off some starry eyed investor, from $175 to 3/4 mill - anything will do. Lets not be tied to any firmly costed development schedule here in the "advantageous product line" until they get a "successful stronghold presence ".
I would have to get an english translation to figure out all the small print - imagine if the proposal and contract were worded personally by Amnon!!!!

[AmnonMikeCohen]

YES Lance, there are many more such cases as you have spotted, and this is why the problem has not yet been resolved by others - the leaking problem as I know it - a problem which has been resolved and where my invention has succeeded. It is worth the development, as I have been told it can add 30% and some claim only 15% additional efficiency - but I have not yet tested my more advanced model of the invention.
In all my writing, you may have not noticed at my website, that I am writing about A Water Lubrication 1st and with OPTIONAL Secured Injection Cavity, and this is what most readers here have been missing, while looking at the Air Cavity idea which has been around and experimented with for many years by now.

Thank you for being one of the respectful members on this website.

For any more information, you can write to me directly, as this thread has been tainted by negative thinking members, and a clear view is not so simple to see anymore!

Ami

This is a reply to the Air Lubricated Hull portion of this thread, not the hijacked portion.

There was a boat on St. John, USVI called "Caribe Air Ride". It was owned by Transportation Services. That boat had a large compressor which pumped air through holes in the outher layer of a double hull. It worked great in protected water, but not in heavy chop. The hull was cut out, the pumps removed and a single, conventional hull put in.

About 30-40 years ago, a small workboat out of Port Aransas, Texas used an auxilliary engine driving two 6-71 superchargers as compressors and upped his top speed from 21 to 31 knots by injecting the air through a small step glassed in at the front of the planing surface. I don't know how his fuel consumption was affected by the extra engine, but his speed came up nearly 50% even with the extra weight.

In controlled conditions, air lubrication can be made to perform very well, they just always seem to have the controlled conditions turned off when I get a chance to go boating.

Lance

[CDK]

Thank you Lance, that is the kind of information I've been looking for.
Of course sea conditions greatly affect the performance of air injected hulls, that is probably why experimenters tried to contain the air in cavities or between fins. But for pleasure craft of 20-30 ft I think it will be sufficient if the system works in a quit sea or lake. Planing in 6 ft waves gives you headaches and kidney problems.
I also think that even a partial air film could save a lot of fuel. If it would be possible to lubricate half of the hull's planing area with air, the effect should be noticeable. Using a turbo charger for that is an excellent suggestion.

[tuantom]

When does air lubrication become too much? If the boat were still, and bubbles were introduced under it, it would go down due to the now decreased density underneath it. Why doesn't this happen while planing? I'm guessing it has to do with the amount of time the bubbles are in contact with the hull - which brings another question: Is there a "critical speed" of sorts where the benefits set in?

[tom28571]

When does air lubrication become too much? If the boat were still, and bubbles were introduced under it, it would go down due to the now decreased density underneath it. Why doesn't this happen while planing? I'm guessing it has to do with the amount of time the bubbles are in contact with the hull - which brings another question: Is there a "critical speed" of sorts where the benefits set in?

I'm pretty sure that any bubbles under the hull must assume the same pressure as the water surrounding them. When the boat is at rest, the bubbles would have the pressure according to their depth underwater. If the boat is planing, the pressure would be higher to account for the dynamic force supporting the boat.

[erik818]

Tuantom,
The boat will not sink when you introduce bubbles under it, at least not when blowing them down throught the bottom of the boat itself. To introduce bubbles require a pressure when blowing the bubbles down into the water, which will create a lifting force for the boat.

It is simply not possible for a boat to sink itself by blowing bubbles under itself. The action would be similar to lifting yourself in the hair.

Injecting bubbles below a model boat with an external device as an experiment in an aquarium is a different case, as are the claimed gasses from the bottom of the Bermuda Triangle.

The problem with air lubrication is never too much air. The problem is to get air where you need it for lubrication when the boat is moving.

Erik

[tuantom]

Now that I've actually stopped to think about it Erik, you're right; and I like the analogy (but you can pull yourself down by the hair ;) ). Gaseous air can never be as dense as water, which would cause the boat to lower (or would the bouyancy of the bubbles lift???) - what I was missing, though, was the lifting force it takes to get the bubbles under the hull - and where it's introduced.
What would happen if we somehow managed to have a sheet of bubbles suspended on half the surface of a lake; and had a boat, which was planing on the normal water, cross into it?

[CDK]

Now that I've actually stopped to think about it Erik, you're right; and I like the analogy (but you can pull yourself down by the hair ;) ). Gaseous air can never be as dense as water, which would cause the boat to lower (or would the bouyancy of the bubbles lift???) - what I was missing, though, was the lifting force it takes to get the bubbles under the hull - and where it's introduced.
What would happen if we somehow managed to have a sheet of bubbles suspended on half the surface of a lake; and had a boat, which was planing on the normal water, cross into it?

That experiment could be done with the help of a large bottle of detergent and an outboard engine to create foam. Or the airport fire extinguishing equipment they use for precautionary landings.
An excellent idea, but I can't do it myself: the sea in front of my house is too agitated and the salt makes it difficult to create large quantities of foam.