Most of the study of Venturi effects (Carburetors etc, etc) are based upon mechanical flow of the fluids being induced (i.e. Fuel pumps etc.)- Not random flows—Surfboards may go from 0 mph to 15 mph, on take off, to 0 mph, if you get air after freefalling into the wave, then back to 15 or 30 mph when you reconnect with the face for an instant–Then–Here comes the turn, and now that water is going 30 to 45 degrees against the grain of the port flow–What do you think could happen then? Try–DRAG–. Like putting an upside down cup in the water, with a hole in the bottom–If using a boat for this experiment, I.E. Water pump, mechanical pump, constant pressure–Face the flow of the cup in the direction of the boat, all’s good and the water rushes in like crazy–Try turning the boat, and hold the cup in the same orientation–Well, things can get ugly fast-- Induction reverses the flow and pulls air in, but then again, it must be oriented in the direction of flow—Same thing on a smaller scale, unless you can change the direction of the induction port as fast as you can change direction–Modern power boats approached this with steps, not unlike John Kelley, and his stepped tail----That is another issue…Mac
My god!!! The intellectual, mind boggling, geometric,mathematical, theoretical, vectoring, drag and volume coefficient calculating physical laws of nature and perpetual theorem is making my brain hurt. I need to take some Excedrin.
This thread is very futuristic. Very interesting.
WINNING !
herb
a few months ago,
bill barnsfield asked me how the finless thing was doing.
i think it's catching on.
herb
I came across this photo of a board made by Dan( Sky Dog )Highland. This is a real back to the Future Board built in the early 1970's Not only is it vented ported and slotted it also has a 3 fin set up. I can't imagine how anyone was able to glass that board.
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''...built in the early 1970's...it also has a 3 fin set up.''
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Actually quite common, at that time.
I prefer fins too. But…
There used to be a great vid of Jamie O’Brien surfing a Beach Break using a board with fin removed. He was tearing it up without a fin. There are plenty of videos of skimmers surfing waves on their skimboards – no fins either.
@ Discussion about Induction Port Negative Pressure:
Regarding the induction ports, I’m not an engineer, but I have a fairly solid understanding of physics. I think the view that rail-scoop drag is the mechanism of what is happening for this design is correct.
I believe the low viscosity/density of air would actually reduce negative pressure more than if the concave shapes/depressions in the bottom/hull did not communicate with the deck surface/air via holes/tubes.
Just my $0.02
Bill, That board was common in the 70's? Now I might not recall everything from that time. I was known to use brain cell killing substances in my youth. Still I would remember if a board like that if it were common.
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Bill, That board was common in the 70's? Now I might not recall everything from that time. I was known to use brain cell killing substances in my youth. Still I would remember if a board like that if it were common.
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Well, it was common for me. I did the prototype of my removable tri fins in Sept/Oct 1970. By Feb 1971, was selling the fins to G & S, Dewey Weber, and using them on Surf Systems, and Surfboards Hawaii boards. So, yes, that setup was in common use.
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Thats a cool board. Cant absorb that its from the 70's !!!
Bill, The fin set up was used in those days i even had some on a 7" diamond tail.
If you re-read my post #166(prior page) you will see that my comment was directed to your mention of there being 3 fins. (even though they could be seen in the photo) It gave the impression that you thought that was somehow significant, and ''advanced.'' While the venting was innovative, there was nothing special about the shape of the board, or the use of 3 fins.
Just a mis communication Bill Gee how could That happen on the internet.