Crazy Idea. Yes, No?

[Krazymaan]

I was recently watching Mega Ships on the Boob Tube and it seems that now a days, huge ships are dumping micro air bubbles out the bottom of the bow to reduce friction which actually makes these Mega Ships go faster and more efficient because of less resistance. I know our boats don't weigh in at 854 metric tons but thats not the point. Plus the fact that you can't really run an air compressor on our boats.
I wonder how it would work if you were drag racing being your supply is limited and you had a bottle of compressed air which wouldn't weigh that much at all to discharge millions of tiny bubbles out the bow under the water. Its been proven to work, I wonder if anyone has tried it on a small fast boat.
It would work like a shot of Nitrous, but free.
Your neck and neck and you dump a shot of anti-friction and take the lead.

[Markus]

Ventilated steps on offshore race boats do about that.

[olboatman]

I would think that could be helpful to sob tunnel hulls where the prop is in clean water and the air would not cause slippage. Gary

[Da Bull]

Yes, It has been done. Ron Baker had a forward thinking and cam up with many interesting concepts envolving boat bottoms. If memory serves i think it was a Viking that Ron devised a tube system that aerated the pad. I don`t know the results but maybe somebody on here will. Sam should.

DB

[mjw930]

Many race boat builders have experimented with various techniques to introduce air into the running surface in ways other than "steps" in an attempt to maintain the handling characteristics of their hull design while providing just that little extra speed. Most efforts turned out to be not worth the time and effort.

I recall one such effort at Velocity where a 26 hull was modified to introduce air at various points along the running surface using a ram air system. It did increase the speed on flat water but It was deemed "not worth the effort" if I recall correctly.

[RocketMan]

I may be wrong but I seem to remember back in the early '70s up on Lake Wallenpaupac in Pennsylvania, a man named Bakker had a display in his boat dealership. The display board showed a patent he had on such a bubbling device. His son(s) still have a boat dealership on the lake.

[TooStroked]

Introducing air to reduce hydrodynamic drag is not a new idea for pleasure / race boats. It is a new idea on big ships though. The advantage is that it reduces drag so a given hull can go faster. The disadvantage is that it also reduces drag laterally - which can make for a pretty evil handling boat in any kind of turn. (YouTube is full of videos of aerated hulls spinning out in corners - sometimes with some pretty nasty results.) Although modern stepped hulls have reduced this tendency quite a bit, they can still be tricky to handle if you don't know what you're doing.

I know a drag boat only has to go in a straight line for a short distance. But there's a good deal of steering required to keep it going in that straight line. Although it might help you go faster, it might also lead to disaster.

[Jimboat]

Many race boat builders have experimented with various techniques to introduce air into the running surface in ways other than "steps" in an attempt to maintain the handling characteristics of their hull design while providing just that little extra speed. Most efforts turned out to be not worth the time and effort.

Yup! It seems that the whole idea of aeration doesn't do anything positive for planing hulls.

[Brad Zastrow]

Jimboat Yup! It seems that the whole idea of aeration doesn't do anything positive for planing hulls.[/QUOTE]


Are you being sarcastic or is that your opinion? Maybe I am not reading this right. But virtually every high performance offshore hull is stepped to aerate the hull.

[Jimboat]

Are you being sarcastic or is that your opinion? Maybe I am not reading this right. But virtually every high performance offshore hull is stepped to aerate the hull.

Brad - I agree with MJW930. Aeration is shown to be of little practical benefit to planing hulls. There's some research that shows that it can help on some displacement applications, though. [The trick on planning hulls is that for micro-bubble drag reduction to work the bubbles must be small and very close to the hull surface
within the boundary layer thickness. This is very difficult to control, particularly at rapidly changing speeds or conditions. If the thickness criteria is violated then the bubbles actually cause less Lift which results in increased wetted surface and increased drag].

Yes, many offshore hulls utilize stepped bottom designs, but not for aeration. A well-designed stepped hull can maintain near optimum angle of attack throughout a speed range and can improve the efficient lift away from the leading edges. Many stepped hull designers do use ventilation of the steps, however, to help mitigate the blowout and tripping that poorly located steps can cause.

[Instigator]

Yes, It has been done. Ron Baker had a forward thinking and cam up with many interesting concepts envolving boat bottoms. If memory serves i think it was a Viking that Ron devised a tube system that aerated the pad. I don`t know the results but maybe somebody on here will. Sam should.

DB

I have a picture of it somewhere Bobby. Very crude, approx" 1 1/2" pvc pipe epoxied to floor/bottom to aerate a step he added to the pad.
Was running it in the Supersport class w/the green 150's. Told me it helped some.

Tony Brucato did similar to his yellow basser. Was experimenting w/steps on the pad. Said it wasnt doing as expeted so he vented it through the bottom into the bilge. Told me he had a hose hooked to it and at speed it would suck a vacuum on his thumb.

[tripower]

My 1980 Challenger 21 has a stepped hull with air tubes that dump out just past the step.

[Instigator]

My 1980 Challenger 21 has a stepped hull with air tubes that dump out just past the step.

Did that come from Rob Twible in Ontario? I think his was red, but had identical set up.

[tripower]

Did that come from Rob Twible in Ontario? I think his was red, but had identical set up.

Nope, the original owner was from Rhode Island. He ordered it new from a Challenger dealer in Canada (it was built there). I bought it from him this past summer. Guy owned it for 36 years and had to sell due to health issues :-(

[eli]

might work at slow speeds to free thinks up but haulin azz would be of no benefits my twister dont need any bubbles its light compared to my 23 daytona which could of used bubbles for cruising