Super wetsuit: warmer, more slippery, doesn't wet

[sebastien murat]

Hi,

Over the last few years I've been experimenting with some novel ways to render wetsuits more slippery and, therefore, faster in the water, but also warmer, without adversely increasing buoyancy. Today, I'm pleased to report that I've managed to develop a wetsuit paint that is both elastic, robust (nothing new here) but also superhydrophobic. This latter quality renders the surface of the wetsuit essentially unwettable. This is achieved by generating a microscopic air layer between the suit and the water. This has at least three noticeable advantages:

Thermal protection: a (thermal) insulating layer is formed between the suit and the water, thereby greatly reducing conductive heat loss. Evaporative heat loss is also limited since a film of water can't form; water instantly beads and runs-off at the slightest inclination of the wetsuit surface.

Non-wettable: immediately upon exiting the water, the suit sheds itself of any water. Coating the inside of the suit similarly renders the suit dry upon removal. If you pee in it, no problem. Simply dunk it back in the water and its instantly clean and dry. You don't have to wash it in freshwater actually because salt stains simply don't have a chance to form, since water instantly beads off. This makes for the suit readily packable and you don't have to do anything to it between dives, even long breaks.

Super slippery: the suit never makes actual contact with the water, because the trapped layer of air; maybe less than a a small of fraction of a percent is actually in contact with the water. This means that there is essentially no measurable (skin) friction between you and the surrounding water. The only friction is between the thin layer of air and water, which is not worth talking about. So, this means that you'll glide further for any given effort, or just simply be able to swim faster. Quite simply it renders any wetsuit more slippery than anything out there, not by a little but several orders of magnitude.

Over the next week or so, I'll film a demo of this pretty cool paint to show you just what I mean. Stay tuned

 

[esom]

what about aging, sun in particular? any experiments putting the new material in a relation to classic smoothskin? there is no nylon layer at all, is it?
cool you took the time to figure this out.

 

[Simos]

Looking forward to the demo Seb - sounds really interesting!

If successful, this could be one of those developments that all of a sudden make much bigger performances possible!

Just a question - sounds like a suit that's completely coated in this paint could adversely affect CNF/DNF? You'd obviously get more glide but on the downside you wouldn't be able to generate as much thrust. Or am I wrong in thinking this?

 

[sebastien murat]

The active ingredient that imparts the special qualities is completely inert, i.e., resistant to salt-spray, UV, and scratching. The active ingredient is not just a superficial aspect but an inherent property of the coating, such that hard scratching could remove some of the coating, but the subsurface qualities are the same as the surface so that the desirable qualities are maintained. The coating will probably outlive the life of the suit. However, it can reapplied It is best applied to an open-cell structure. An open cell structure dramatically increases its adhesion. I'm about to do some trials on a nylon and will post results shortly. Buying a smooth skin and applying this paint would serve no benefit. A suit with an open cell structure and, therefore, cheaper would be smarter.

 

[sebastien murat]

Simos,

There is a trade-off between glide (=> slip) and thrust (=> grip). It would be possibel to get the benefit of both by fulling coating the suit with a toothed-spatule that generates small longitudinal ridges and troughs. In this way, when the ridges are oriented perpendicular to the flow, in the catch phase, they would generate turbulence and minimize slip. This would have a minimal effect on increasing the overall surface area of the suit and, hence, skin friction because we're still only talking about an air-water interface.

 

[Simos]

The active ingredient that imparts the special qualities is completely inert, i.e., resistant to salt-spray, UV, and scratching. The active ingredient is not just a superficial aspect but an inherent property of the coating, such that hard scratching could remove some of the coating, but the subsurface qualities are the same as the surface so that the desirable qualities are maintained. The coating will probably outlive the life of the suit. However, it can reapplied It is best applied to an open-cell structure. An open cell structure dramatically increases its adhesion. I'm about to do some trials on a nylon and will post results shortly. Buying a smooth skin and applying this paint would serve no benefit. A suit with an open cell structure and, therefore, cheaper would be smarter.

Apart from the outside, are you going to try coating the inside too? Sounds promising, especially on the 'wear and tear' front which is usually where smooth skins can be a bit of a let down.

Also, if you can make it in appealing colours (or even just black), I'd gladly buy some and paint my smurf-blue Elios!

Would be cool/useful if you could somehow quantify how much glide you get in comparison to say a smooth skin. Should be fairly easy to test in the pool and measure...

 

[Azrael3000]

Am I right in the assumption that you use some sort of nano particles to achieve a lotus effect?

Anyways it sounds very interesting. Looking forward for more on it.

 

[Simos]

Simos,

There is a trade-off between glide (=> slip) and thrust (=> grip). It would be possibel to get the benefit of both by fulling coating the suit with a toothed-spatule that generates small longitudinal ridges and troughs. In this way, when the ridges are oriented perpendicular to the flow, in the catch phase, they would generate turbulence and minimize slip. This would have a minimal effect on increasing the overall surface area of the suit and, hence, skin friction because we're still only talking about an air-water interface.

Thanks Seb - makes sense and in fact I was thinking along the same lines i.e. that if someone could create a suit some kind of material that has difference properties according to the direction of flow, it would be very beneficial.

I am sure we could find examples like this in the animal kingdom... Anyway looking forward to seeing the results of your trials.

 

[sebastien murat]

Just checked some stats on the contribution of skin drag (Dsk) to total drag under various strokes, at the surface and u/w (cf. Pendergast et al. 2005):
- 25% for swimming at the surface (crawl)
- 40% for swimming at the surface without fins

- a whopping 75% for swimming u/w with fins ... since the wetted surface area increases dramatically and drag can now only be redistributed between pressure and skin drag; wave drag practically disappearing.
- without fins ?, but must be higher than 25% for reason given above

This suggests that coating not only the suit but the fins also would reap substantial rewards. It will be very interesting to trial this to proof of concept.

To be fair, however, I think that the effect will be partially gradually lost with depth since water pressure will cause water to invade the air film, i.e., unless some bubbles were exhaled into the slipstream so as to re-institute the air layer, again a trade-off, but potentially doable

 

[sebastien murat]

Guess it could be used on kayaks, water-skis, and other shallow draft watercraft since its waterproof. Don't know how it would fair under skis with the extra weight. I'll just have to try this winter.

Generating different colors is no problem. Interestingly, however, when viewed from underwater at angles around 40 degrees or shallower the coating renders the suit like a mirror, so that it reflects what's below and you can't see the human shape very well. The less the curvature of the suit the more `invisible´ it becomes. Good thing if you're afraid of shark attacks from below I guess.

I don't know what would happen if you blew bubbles over the suit at depth, but my guess is that you'd have a weird effect when looking at it from various angles, perhaps something like the trippy camouflage jungle scenes from Predator.

Azrael, the recipe has to be a secret.

 

[Simos]

unless some bubbles were exhaled into the slipstream so as to re-institute the air layer

...ideally by a dolphin passing-by

 

[esom]

what about the slip on dry skin? - you mentioned the option of putting it on the inside for other beneficial reasons

cheers

Azrael, the recipe has to be a secret.

who says so?

 

[Azrael3000]

Fair enough Seb.

If my theory is correct, then indeed the effect should be lost at depth. However, it could be that due to the structure of the suite small eddies are formed close to the suite that cause the surrounding water to slip by easier. The same effect that occurs close to the skin of a shark.

 

[Azrael3000]

who says so?

Well I guess Seb will want to sell it and why shouldn't he. He needs to eat like the rest of us and maybe that gives him some independence from sponsors.

 

[esom]

no offence at all, by the way. it´s far enough if it´s a question, if it "has to be...". my two cents

 

[sebastien murat]

Correct I too have to eat! I tried the other way, just living off air and sunlight, but I realized I wasn't a plant!

 

[esom]

lol- at least not a mangrove


edit: what about the slip on dry and wet skin i mentioned above?

 

[Apneaddict]

Should get someone to set a new WR with it before hyping it... Great marketing opportunity.

 

[sebastien murat]

Point taken...thanks. Have to think about this carefully since there are rules and regulations regarding the use of suits in triathlon and swimming.

 

[fcallagy]

Seb if this could be applied to the underside of surf boards and would give a mirror effect you could save both the lives of surfers and of sharks and make a ton of money in one swoop.
Really really hope it works out.