Plus One has always given direct, credible and detailed responses about design tech and SB performance.
George Gall has always addressed SB tech straight up.
Much respect for the mathematician, engineer and skilled surfboard designer/builder!
My humble opinion…
Hate to see GG take heat.
The guy has been thru a lot, a wealth of info is in his head.
Reminds me of ages ago, "just shut up and try to understand what you are being told.
Yup!
I am a believer…
Hate to kiss ass, except I’ll witness
Spent 3 years trying to “improve” a design he turned me on to.
Worthless folly. I am back to the beginning ( exactly as told).
Big Aloha GG…
What are your Opinions About Channels etc?
I commented on this design feature several times .
It became a thread about" proper" interwebing and a bit of shaming , with no real disscussion of the subject those same posters .
This will be denied endlessly by those guilty of this .
Picture worth a 1,000 words 
…regarding this last photo channels, since I saw them for the first time decades ago, I always though that the logical way was the other way, I mean, with the wider part on the middle part of the board not this way. Like a V (not venturi of course but same V idea)
So, like you are an advocate of channels, what s your opinion about the two possibilities?
To me it’s like pouring water in a funnel. As the funnel narrows there’s resistance to the volume of water being poured in and it slows down the process (drag?). Turn the funnel around and there’s no resistance at all, or at least minimal. I AM a high school graduate, not a rocket scientist. (standard disclaimer)
I can see how toe in might magnify any low pressure effect created by channels.
Seems like the reverse would increase pressure, neutralizing any low pressure effect created by the channels.
EDIT:
Describing the channel effect as “low pressure” is a generalization on my part. As I understand the Coanda effect, the faster moving water would “cling” to the convex bottom surface of the channel as it enters and flows through. Low pressure is a component of the effect though.
This shot from the tail exaggerates the toe in
Its 1/4" in 9"
Guiding water rather than capturing it , always less pressure as you go rearward for the flow to move into at any speed .
I shorten the fins around 1/4" to balance this directional bottom back to the drift of a normal board
Only this time as it constantly drifts there is a very noticeable flow out the back - accelerating the board always - constantly
“Its 1/4” in 9"
So the channels run at an angle of 1.59 degrees to the (stringer) center line?
if channels are functional in the back what about the mid upper half of board too? If you are going to piss off a glasser and sander you might as well do it right.
^^ the answer to the “how do you do it?” question can’t be explained any more clearly than that.
It is a place to start.
Channel depth, width, length and cross-sectional shape would likely have a significant effect; assuming the best channel design is known. Should the bottom of the channel be laterally/longitudinally curved or flat? Walls straight/angular or curved?
What is the correct number of channels?
BB30 has raised another important design consideration. Where is the best placement? And I would ask why?
The constant acceleration has still got my attention…
I go with what works, not theory. Don’t take it so personal. At any give really good Surf spot on a. Good day the “fastest” surfboard is under the feet of the best surfer. 90% of the time that is NOT a channel bottom. Don’t get me wrong asshole; I believe they are credible to a point. You shape a nice one. And so did Byrne. But other than tweaking them and playing with the fins they are limited and cannot progress beyond certain perimeters. Theory is your specialty, not mine. You and you brown nose groupies can stick your commercial for “the Grif” surfboards where the sun don’t shine.
Greg, Just taken a good look at the boards you’re building. Awesome stuff and thanks for the input.
I’ve been thinking of a single channel twin/quad similar to the pics Huck has put up. In yours (or anyone else) opinion what would I expect under my feet surfing something like this? Would I notice the difference between a full length and tail only channel of this design? (assuming channels are similar width and depth)…Steve
Ever since I saw the Mike Daniel single channel tail 7 years ago in his finless, I have been thinking about it.
http://www.swaylocks.com/comment/361614#comment-361614
I made a quick unglassed XPS bodyboard for the kids a few weeks ago with a short, single tail channel. I got a few rides but not enough to make any definitive evaluation.
With the right design (length, width, depth, shape), I think a single tail channel could create some unique performance subtleties. Several channel design possibilities to be tried.
I believe a tail channel would perform differently than a full length. I could only speculate about the performance differences based on the effect I mentioned in previous posts.
To be fair, i am a fool and a bad surfer 
just built 4 boards up till now, thanks for helping me making them. Appreciate the input.
Just some assumptions from my observations:
Water doesnt like to flow in a straight line. Its creates ripple and resitance.
So why shaping straight channels? Nowhere in nature e.g. planes, boats and stuff like that a straight shape works well…
Think of race skis… They always got a profile, straight cut channels dont work on warm days because the water needs to be put away from the surface of the ski. Instead on real watery days, they cut a V like pattern to make the ski run fast.
So why not bend them to allow the water to flow free and fast, maybe creating some lift on top? It kind of shows octavic patterns on the surface.
Why not shape the channels in proper harmonical size and angular? I think the Jigg Bottoms worked that kind of way… Kind of a similar technique also was used a century ago to float bigger logs from mountains to the valley.
http://www.co-bw.com/Music_how_do_woodwinds_work_files/columns.GIF
You can read my description of how they work this way a few posts above
You only plane on a short area at any time also .
I can write book from experience not boats , airplanes , birds , ducks etc .
No one taught me , there was no intwereb demanding information while I learned what did .
I am a lousy interweber who has made very functional surfboards my whole life
Well we all keep on experimenting because its not boring
