new product .....

…I’m not sure if I posted this on P-Net but I’ll post it here. I recently mentioned this in another thread but I think it deserves it’s own thread. A new superhydro-phobic coating is supposed to be on the market within the next year( if not already). I think it would work well with kevlar and fiberglass and hopefully poly boats. It’ll have other uses also, cars, clothes etc etc.

yeah I’d try some …
… wonder where I can get a can to try ??

Sounds good…
…I intend to apply to myself and ditch my drysuit asap :slight_smile:

been eagerly following…
they say a spray on version will be available late summer or so. Biggest question for me will be price which will determine where it’s practical to use.

I’ve seen the demo videos and it seem pretty impressive. They sprayed some on white tennis shoes and stepped into a mud puddle and stepped out still pure white. Had a metal plate in salt water for a year and when they pulled it out all water would immediately and completely bead and fall. They sprayed in iphone and left it in water for 30 minutes while running.

Durability is key since some other less hydrophobic products have also worn off quickly. If it works one could spray much of their gear and then when you step out of the water it would be dry. More important maybe is that your gear would have no salt residue because that mostly only happens from salt water sitting long enough to evaporate.

Staying hopeful but skeptical.

Great for shoes, boots, but WHY would
I use it on my boats?? It won’t make them faster. It won’t preserve them from degradation. Why?

Waste of Money and Time
Simply rinse boat , maybe use terry cloth towel,

and let it dry most days is just fine.

Use a bit of 303 protectant for sunshine UV.

Easy peasy and nothing else is needed.

Even the pro racers use nothing, nada, zilch

on the hulls of their expensive boats.

Possible salt water
Salt water has different stickiness issues than fresh. We have to spend extra time rinsing things off, especially vulnerable stuff like rigging, when we are parked at the shore for an extended period. It’s not an impossibly big deal, but it’d be nice if we could be less attentive about it. Kind of like being able to Scotch-Guard the perimeter lines for anyone old enough to remember.

i was kinda thinking…
…if you applied this stuff to a boats hull, that would reduce “stiction” and the boat would , should, glide easier and therefore faster, with less effort than the surface tension drag normally associated with boat hulls.anyone who has ever waxed a hardshell boat knows it immediately glides much easier and faster than a untreated hull.

gotta argue the point…
Hi willi…i have to argue the point , not to start a pissing match, but yes racers do wax their boats when applicable, they just don’t admit it , thinking it’s their “little secret” and it don’t matter if it’s a kayak/canoe/ or a America’s Cup racer or a hydroplane. anything that reduces the Stiction of surface water on a boat hull is a plus.

stiction [ˈstɪkʃən]…(Physics)the frictional force to be overcome to set one object in motion when it is in contact with another.


– Last Updated: Apr-26-12 11:27 AM EST –

Note that the manufacturer of the product claims anti-wetting, -icing, -corrosion, -bacterial, and self-cleaning properties, but not drag-reduction.

Changing the wetting properties of a hull will not reduce skin friction. ALL surfaces exhibit the no-slip condition, which means that the layer of water in direct contact with a hull sticks to the surface, hence it moves at the same speed as the hull. Fluid friction results from the interaction of this fluid layer stuck to the hull with the fluid layers in relative motion next to it. All hydrodynamically smooth surfaces are equivalent, which you can verify by looking at a Moody Chart.

A hydrophobic coating can only reduce one portion of the drag of a body in water - that due to the meniscus, the curved surface of the air-water interface where it meets the hull. A non-wetting surface will have a meniscus that curves downward, not upward as usual. This reduces the wetted surface area by a tiny amount, and will reduce skin friction in proportion. As this is a vanishingly small amount of drag (unless you happen to be a water-skimming insect), it is a pointless exercise.

The coating may reduce drag as a secondary effect, by preventing the build up of crud on the hull, but one could do that with a rag as Willi pointed out.

more about salt on gear
After every paddle I hose off several items. I also take the boat from the car to a stand, rinse, flip, rise, empty then move to storage spot. With this product if it’s not too expensive I could in theory spray PFD, skirt, boat and some other items then when I get home I just take boat directly to storage and hang other gear to dry without rinsing. One application should last a year or more if what they say is true. Easily saves me 15 minutes every day I paddle (which is often a lot). I’m not looking to speed my boat, just make life with salt water easier.

I’d love it if this or something similar (similar products are in the works) could be used on sunglasses. I don’t use sunglasses when surfing my kayak because it can take a minute or so for spots to clear and in the meantime it’s hard to see that next big wave heading my way.

The implications of a product likre this has enormous promise for a wide variety of applications!

Wash my car, spray this stuff on everything, just rinse to keep clean!

Argue with John Winters
noted canoe designer and naval architect and yes I believe he raced.

boundry layer?
It’d be interesting to see how this affects the boundary layer of an immersed object.

FWIW, the successful drag-reduction coatings I know of have been hydrophilic, not hydrophobic. Some have attempted to mimic the mucus layer on a dolphin’s skin. The problem is that they’re ablative and can be regarded as a pollutant.

VHF radio
Could be good for preventing that white crusting on electronics devices.

Would love to treat my truck with it against road salt but that would be prohibitively expensive.

It won’t

– Last Updated: Apr-26-12 3:06 PM EST –

A smooth surface is a smooth surface - the boundary layer will be the same as long as the Reynolds numbers are the same. What alters a boundary layer is roughness, primarily.

The long-polymer additives that have been used in the past to reduce drag are able to function because they are ablative, as you say. They leave the surface, mix with the fluid and modify the motions in the boundary layer.

The last I heard, the theory was that they alter the velocity gradient in the near-wall portion of the BL by stretching within small eddies, reducing the shear rates there, but I don't think anyone really knows what the details are.

Useless for kayak speed

– Last Updated: Apr-26-12 3:38 PM EST –

The faster you try to go, the larger the
turbulent boundary-layer becomes, with a
sharp increase in chaotic water flow near the hull.
The boundary layer exists, regardless of "what" you
smeared on the hull of any kayak. The frictional forces
are water-on-water.
Keeping the kayak hull clean and free from scratches
will help you maintain speed better than any wax
or goo from the store.

The amount of surface tension reduced by micropolishing
super smooth kayak hulls is literally less than 1 %

Form refers to stuff like a plumb bow, amount of waterline, etc on a physical kayak shape

Actual testing has showed that waxing
slows a hull. RainX slows a hull.

If a hull is totally smooth to begin with, wet sanding the surface with very fine sandpaper may improve the way water sticks to the hull, but I don’t think anyone has found the difference to be worth the maintenance.

I once added a new epoxy skin to two whitewater boats that had gotten fuzzy. On the faster one, after fine sanding with a random orbit sander, I sprayed on a product claimed to make speedboats faster. The kayak certainly felt faster, but it might have been only placebo effect.

The best thing about boat wax is that it usually has some UV inhibitor, so it protects the resin from sun damage. It makes the boat easy to drag, if that’s what you want to do. It may make the boat slip over rocks more easily. But it does not make the boat faster.

Racers? When I was rowing in the 60s
our coach at MIT consulted the Naval Architecture department, and then had us wet-sanding the hulls of our 60 foot shells. But no one noticed any improvement. All it did was temporarily psych out some of the other teams.

If you have seen marathon racers wax hulls, I imagine they did it because some drag hulls over portages. The wax does make them slip easier.


– Last Updated: Apr-27-12 2:47 PM EST –

I have to correct one misstatement - as you go faster, the boundary layer actually gets thinner. The thinning is part of what increases drag, as the velocity gradient at the hull is steeper, both because the velocity differential is higher and the layer is thinner.

This is why fast boats need to be smoother - a thinner boundary layer is more sensitive to smaller roughness elements on the hull, because they physically protrude into the thinner BL. A hull that seems smooth at low speeds may be rough at higher speeds.

BTW, I'm on track with everything else Willi says above.