From ST tech center
"PULLING SURFACES
Though I’ve had my wetsuits tested at the flume in Colorado Springs, I’ve reliably found that the most precise wetsuit “feature” testing was accomplished at the pool. You put a guy (or gal) in a “featured” suit, he swims 3 x 200m, then you put him in an “unfeatured” suit (exact same suit without the “feature”), he swims the same set, then he’s back in the first suit for another set, and so forth. After four people swim four sets in the same pair of suits, you have a pretty good idea whether a new feature is fast or it’s not.
Back in the early 1990s we put “pulling surfaces” in our wetsuits. These were forearm panels that had irregular textures that would theoretically stick to the water during the pull. I took these suits to Interbike. I got my dealers all jazzed up over them. I took orders. I thought I’d taken a giant leap ahead of my competition. I had only omitted one thing. I never tested these pulling surfaces.
So, before I commenced production on these new super duper wetsuits, I decided to go through the perfunctory formality of testing them. Besides, I wanted to see just how much faster than a standard pulling surface these new designs were. My worst nightmare was that they would be no faster at all.
No need to have been concerned about that. These new secret speed suits did not exhibit speeds identical to the “unfeatured” suits. They were slower.
I was crestfallen. But also curious. So, I put on my goggles, held my breath, and watched underwater as swimmers stroked past me with these new suits on. It was immediately obvious what was happening. With each catch air was trapped by these surfaces, and whatever techniques swimmers used to shed the surface of water did not work when using these suits. Air bubbles came streaming off the arm during the pull phase.
I write this because there is frequently a disconnect between what seems intuitive and what is in fact happening. “One test is worth a thousand expert opinions,” engineers are fond of saying, and it was fortunate that I did not equate intuition and logic with sound engineering (well, I did in the beginning, but fortunately repented before it was too late). Had I not tested these suits, I would’ve been charging my customers extra money for a slower product.
I do not mean to imply that today’s pulling surfaces (examples include “Phase I Catch Panel,” “grooved panel,” “waffle grid pattern,” “aqua-grip,”) are actually slower than standard wetsuits. They may well be faster. Wetsuit designers may have figured out the secret to the “pulling surface.” However, I have not yet seen any study of these surfaces, and I have not found a manufacturer who sells this feature (many companies do) who can provide me with its testing “spreadsheet.”
Accordingly, I would question the utility of such a feature until somebody demonstrates to my satisfaction – with an empirical argument, not a reasoned one, nor one with anecdotes – that these surfaces work. Until then, I must assume that they belong in the same category as carbon seat stays, that is, this feature might work and it might not, but it certainly is sexy."
