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

[nostres]

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

Two cans for me please, one red, one silver and a PayPal invoice to piuro76@yahoo.com

 

[sebastien murat]

Almost to good to be true hey. Early days yet, but after maybe a hundred trials and several years of research it looks promising. From a purely invisibility point of view it has a lot going for it, as it would be shape altering, but like I said, only as long as its not in Snell's window, which is a substantial proportion of the viewing field. Haven't tried pressure tests but maybe it can handle several decimeters. Re-aerating should be pretty straight forward.

 

[Andrew the fish]

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?

I think you are wrong in thinking this. Reduced surface drug will actually improve thrust generated by indulations.

Think ice scates, they need no teeth to generate thrust, they are equally "slippery" in both directions but move you forward nevertheless.

 

[sebastien murat]

At first guess: Ice-skates propel you forward because of the lateral forces applied to the skates, otherwise you'd be doing stand-stills surely. The glide, however, probably occurs on water, since the pressure on the tiny surface are of the blades probably turns ice into water, otherwise there be too much friction to move very far forward (or backwards)

 

[Andrew the fish]

sebastien, I am not sure what you were trying to say. Ice scates was just one example. Try casting boards (Ripsticks), airplane wings or ship's propellers. None of those will ever suffer loss of propulsion due to reduced surface friction.

 

[esom]

sebastien, I am not sure what you were trying to say. Ice scates was just one example. Try casting boards (Ripsticks), airplane wings or ship's propellers. None of those will ever suffer loss of propulsion due to reduced surface friction.

and ice skates are able to push you forward because of their high friction. in lateral direction.

but your point is very clear and interesting- will look up biomechanics of armstrokes...

edit: read a little, doubt it makes sense to descibe. but maybe swimmers who tried the ian thorpe like long sleeve low friction suit can report. well- maybe the arm have another surface quality in those suits i don´t know. anybody?

 

[guybly]

I for one would like to order a couple of liters of this stuff, it sounds pretty handy for all things water.

Cheers,
Guy

 

[sebastien murat]

Just last night I put some wax on a piece of wood that was lying around and then pressed into the wax some of the stuff; a thin layer only. It gave the same effect: water simply bounced of like it was mercury and I couldn't get it wet no matter how hard I hosed it down. However, when I applied hot water, the wax melted and that was that! How stupid! When I did the same with the dried out paint coating, no problem. Still, not many places where you be playing around boiling hot water I guess.

Also, tried things like ketchup, beer, and salad dressing. It gave the same +ve result to splashing. It could also have an application for cameras in housing, since you could redirect the flow water away from the camera.

I need to try it next in the rain, under the impact of large and heavy droplets to see if it can resist invasion.

Starting to look very cool indeed.

If anyone knows of any really good wetsuit paint manufacturers (not resellers) that I could access to use as base for mixing this stuff with it would be kindly and greatly appreciated.

 

[Siku]

I think you are wrong in thinking this. Reduced surface drug will actually improve thrust generated by indulations.

Think ice scates, they need no teeth to generate thrust, they are equally "slippery" in both directions but move you forward nevertheless.

I'm not sure about this at all, but should we distiguish between:

a) motion provided by pulling, and requiring friction (eg crawling, cycling)

and

b) motion provided by displacement, i.e. push something back to create thrust - Newton's third law (e.g. jet propulsion, finning)

Not sure which breast stroke is? Hmm...

 

[sebastien murat]

Thrust and skin-friction cancel out for a human swimmer at speeds and body lengths we're practically talking about. In other words shaving your arms or keeping your fingers spread in the pull stroke makes no difference, though it may seem like a good idea. The most important thing in the stroke or thrust phase is your form drag, i.e., the shape you present to the water. It is only a good idea to minimize skin friction if you can engage in longer glides. That's because then your not thrusting. In this case, shaving-down or wearing a smooth-skin is a definite plus.

What does this suggest? That the advantage of having gripping panels along the arms provide, as some manufacturers would now have you believe, actually provides no advantage at all. In fact, they will prove to act to increase skin-friction in the glide, unless you can conceal them or they have special skin-friction reducing properties (highly unlikely). But in that case why have them at all since they don't help. Good. Now I don't have to think about having lateral ridges on the arms.

 

[Andrew the fish]

Not sure which breast stroke is? Hmm...

in relation to freediving, what breast stroke are we talking about .

 

[Siku]

By thrust do you mean displacement of water - my (b), above?

In, say, a dolphin stroke, the thrust is the amount of water displaced, and will depend on the form, frequency and amplitude of the stroke. I don't see that this will change depending on the friction (except in so far as the friction might enable or otherwise alter the stroke). The thrust generated is obviously higher than the friction, or there'd be no movement, and the less friction the better, as you say. Same in the glide phase. So shaving, I guess, must help.

But I'm not sure that keeping your fingers spread in the pull stroke makes no difference. In the case of the pull, the inertia of the water is crucial. The greater the area that can be held, the greater the mass of water and resulting the inertia. Like Michael Phelps big feet, gripping panels along the arms catch a greater volume of water.

Having said that, if the propulsion is provided by the (slow and inert) backward movement of the water, then it's the same principle as the dolphin stroke - big hands being equivalent to a wide amplitude stroke.

So maybe less friction makes no difference - you just get less propulsion but with a more effortless stroke?



BTW, if gripping panels do work, wouldn't they avoid the increased skin-friction in the glide by being be shaped so that the passing water keeps them folded down, offering the friction-less surface to the water. And isn't this roughly what a lot of fishes fins do?

 

[sebastien murat]

What I mean is this:

There is the notion, especially amongst swimmers, that it may be better to shave the arms, as this reduces friction in the recovery stroke, despite the small losses in thrust, because of the now greater slip, during the power stroke. The fact, however, is that these effects cancel each other out, so no gains using this approach. The gains would only work for something the size and speed of a flagellum; to do with the complicated world of Reynolds numbers, etc. What I'm referring to is those appendages or places on the appendages going back and forward (i.e., mirror images of one another) to propel you, not about shape altering form-drag effects, like increasing surface-area or using curvilinear motion to hold more water and prevent slip, which are of course very important. I'm not saying shaving or wearing a slippery suit is not a good idea, one must think however what exactly is happening and where.

Let's visualize the upper and lower part of the upper arm, one location that pretty much goes symmetrically back and forth. The grab panels provide extra thrust when the arm moves backward but then the extra friction on the recovery slows you. So, no advantage. The panels would need to be like, e.g., scales that can catch water on the stroking phase and then depress and tuck in the recovery. But now we're talking about shape changing effects, which is not what I'm referring to here.

 

[trux]

Seb, if your coating works for wetsuits, it should work for boats or submarines as well. So if you have a tested product, better than looking for a wetsuit coating manufacturer, you could start negotiating with the Navy and shipyards - such a coating on a big ship could save tons of fuel, and you'd be a millionaire quickly.

In the same time, of course, I hope we'd see the wetsuit coating soon anyway

 

[BennyB]

Hi Seb,

How would this material go when tracking a freediver with a fish finder?

Cheers,
Ben

 

[Haydn]

I would love to test this on my raft. Can I buy some straight away?

 

[sebastien murat]

I would love to test this on my raft. Can I buy some straight away?

I'm only in the R&D phase. I'd have to scale-up substantially to offer any to you in sufficient quantities, and I've got to see how cost-affordable it would be. My target will most likely be water and snow sport equipment manufacturers

 

[sebastien murat]

Seb, if your coating works for wetsuits, it should work for boats or submarines as well. So if you have a tested product, better than looking for a wetsuit coating manufacturer, you could start negotiating with the Navy and shipyards - such a coating on a big ship could save tons of fuel, and you'd be a millionaire quickly.

In the same time, of course, I hope we'd see the wetsuit coating soon anyway

The problem with fast moving displacement watercraft especially those with lot of draft or indeed fully submerged ones (e.g., submarines) is that the water pressure acting on the `skin´ would cause water to invade, resulting in loss of the water film. So then you'd need to regenerate the air layer with aerators, which would increase the cost substantially. Water pressure from speed would be a problem. I once saw a US sub go from Melbourne to Sydney, and to get there in the the time it did, I calculated it must of being too no less than 80 knots, so that's a lot of pressure on the hull front.

I haven't tested the max depth where the film becomes ineffective yet, but according to my calculations, it should handle a depth of at least 1-2 m. That being the case it would be ok for swimming/triathlons, and, say, freediving for distance in the pool, or maybe even canoes/kayaks/surfboards/rowing and skis/snowboards. Of course with SCUBA you'd just purge your reg and there it would re-appear.

I have my doubts that at really high speeds/water pressures, like water-skiing, or a fast planning hull it would work. Despite the ability to aerate I think the water pressure associated with the speed would be perhaps too much and invade the film. I can do the calculations, but in the end the only thing that matters is the actual test.

 

[sebastien murat]

Hi Seb,

How would this material go when tracking a freediver with a fish finder?

Cheers,
Ben

Its a bit out in left field. I don't know what the effect would be of placing an air-layer, especially of such small thickness. Maybe someone knows.

Top of my head, it wouldn't affect it because when you dive for depth the pressure increase would collapse the film, rendering it useless. The only benefits would be in the first few meters of the descent or, if you exhale, like Eric at -25m, on the ascent. When you add air to the surface, i.e., underwater, its so hydrophobic that bubbles quickly pancake and spread to cover the surface. In this really particular case you could then get some significant performance boost....maybe. Does that mean you'd then disappear? probably not, unless you can breathe-out air through the top of your head!

 

[Kars]

I think those ocean going sail race boats would be very pleased with it as well.
You could develop different types for different applications. Does it work as anti-fouling?

How expensive are the ingredients, can you make it in small quantities, and in big ones?

You can call your product mirrorskin, just a idea.

Are you able to make it affordable for regular consumers?
Can you use it on stretch Nylon swimsuits?

I think if the rubber underneath is solid enough water ingress at depth may not be such a big problem.
It's pleasing to know we got another cool freediver/inventor developing cool stuff. And actually I'm happy it's not suited for an army, they already got enough killing power.

I'm looking forward to some test numbers and maybe a nice small video.

Godspeed.