High-Speed Waveless Boat

[kach22i]

Airboats are not hovercraft.............story of my life explaining the difference - and there are many.

Hovercraft are not "displacement craft". That is to say they do not displace water to achieve buoyancy. They hover on a cushion of pressurized air contained at the sides by a flexible curtain known as a skirt. The air leaks out the bottom, which in affect air is the lubricant allowing the craft to slide along the surface. This is why the French call them "air sliders".

Once an airboat (or aeroboat) gets up to speed they don't create much of a wake, but they are still a displacement craft. Airboats are boats, however hovercraft are registered as watercraft in the United States.

Confused yet?

Ever play air-hockey?

[waveless]

Once an airboat (or aeroboat) gets up to speed they don't create much of a wake, but they are still a displacement craft.
=================================
that is correct, and the component of forces of hovercraft will generate wave too.

[waveless]

I also have designed a high-speed submarine that is like a dolphin, the dolphin submarine can flying on the surface of the water, and dive into the water. it can glide under water and drive by batteries. the principle of the dolphin-submarine is same as waveless boat, it have a long fin out of the water. if I have time, I will draw a 3D model here.

[Leo Lazauskas]

Originally Posted by waveless

Sorry, my poor english,

Do you have any experimental results or wave resistance calculations to support your idea? "Pulling water" into the space left by the hull using a screw prop does not necessarily mean that the velocity of that water will produce a waveless solution. And what happens when that water "stops" at the tail?
=======================================================
I had done experimental test in my bathtub, the results is perfect.
without screw prop fitting in the front, you will get more resistance.
the high speed water is slow down at the tail.

A bathtub-size model is probably not big enough. At that scale surface tension will wipe out high-frequency (diverging) waves which is where most energy is going at high Froude numbers.

[kach22i]

Originally Posted by waveless

I also have designed a high-speed submarine that is like a dolphin, the dolphin submarine can flying on the surface of the water, and dive into the water. it can glide under water and drive by batteries. the principle of the dolphin-submarine is same as waveless boat, it have a long fin out of the water. if I have time, I will draw a 3D model here.

This is one of my bookmarks on my computer, you might want to look at it.

http://www.innespace.com/

[kach22i]

Originally Posted by Leo Lazauskas

A bathtub-size model is probably not big enough. At that scale surface tension will wipe out high-frequency (diverging) waves which is where most energy is going at high Froude numbers.

That's the most intelligent thing anyone has said on this thread.

I'll let you take over now.

I'm no engineer, I bow to your expertise.

[Leo Lazauskas]

Originally Posted by yipster

narrow deep and wide shallow, must have done it all without knowing what i was doing

for CFD (Computer Fluid Dynamics) check and try Leo Lazauskas Michlet 8.05 Pro - Free again! Michlet 8.05 Pro - Free again!
you may also like to try other programs like http://www.acricfd.com/software/CFDStudio/default.htm

Strictly speaking, Michlet is not a CFD code. Thanks for your promotion though - you can have 10% as an agent's fee.

[waveless]

A bathtub-size model is probably not big enough. At that scale surface tension will wipe out high-frequency (diverging) waves which is where most energy is going at high Froude numbers.
==========================================
I am a computer engineer, no ability to do the test. I think that is posible to solve the problems by changing the size and speed of the screw, and also can fix the screw prop to the middle of the boat.
-------------------------------------------------------
High-Speed Waveless boat is my dream, she will come to the world.

[Leo Lazauskas]

Originally Posted by waveless

A bathtub-size model is probably not big enough. At that scale surface tension will wipe out high-frequency (diverging) waves which is where most energy is going at high Froude numbers.
==========================================
I am a computer engineer, no ability to do the test. I think that is posible to solve the problems by changing the size and speed of the screw, and also can fix the screw prop to the middle of the boat.

There might be some advantages such as better inflow to the prop, but I doubt that you will get a large decrease in wave resistance and wave-making. Don't let that stop your experimentation though!

Some of my ideas for wave wake reduction can be found at:
www.cyberiad.net/wakeimages.htm

See "Weinblum" and "Tetrahull Animation".

Good luck!
Leo.

[kach22i]

RE: www.cyberiad.net/wakeimages.htm

Great, loved it..............will you ever do images for Hovercraft and Hyrofoils?

[Leo Lazauskas]

Originally Posted by kach22i

RE: www.cyberiad.net/wakeimages.htm

Great, loved it..............will you ever do images for Hovercraft and Hyrofoils?

You can find some images of very low wave resistance "hovercraft" in a paper I co-authored at:
www.cyberiad.net/pd.htm

There are more images in "Wave patterns and minimum wave resistance for high-speed vessels":
www.cyberiad.net/wakepredict.htm

Your "dolphins" are delightful. Can they sense when there is trouble at the mill, or that Gramps is being held hostage by bearded ruffians?

Leo.

[kach22i]

Beautiful, thanks.

I'm not getting access the full user's manual for Michlet Version 8.05. Do you have any tips other than what's in the instructions? Only 1 of the 16 catagories is working for me.

[Leo Lazauskas]

Originally Posted by kach22i

Beautiful, thanks.

I'm not getting access the full user's manual for Michlet Version 8.05. Do you have any tips other than what's in the instructions? Only 1 of the 16 catagories is working for me.

I'm not sure what you mean. I just downloaded the file myself and unzipped it. When I load the file "michman.htm" into my browser I get the index to 16 sections. Each section can be accessed by clicking on the appropriate line in the index.

Leo.

[kach22i]

Time to call in the computer guy across the hall then. Thanks for checking it out for me. Cheers George/kach22i.

[Leo Lazauskas]

Originally Posted by kach22i

Time to call in the computer guy across the hall then. Thanks for checking it out for me. Cheers George/kach22i.

My pleasure.

Please keep in mind that Michlet is not an easy program to use. And be sure that you really need to calculate the drag for whatever project you are embarking on.

All the best,
Leo.