Has anyone tried an application of, say, Armor All - or something similar - on the outside of their boat to reduce skin friction? Thoughts?
Skin Friction
- Thread starter Kayak Jack
- Start date
Reducing scratches and grooves would help reduce friction and let the water slip off the hull better. Would wax or floor polish be hard enough to fill those scratches and not create thier drag? Not sure.
Opposing that is the golf-ball dimple effect to reduce drag but that involves Bernoulli principal, fluid mechanics, boundary layers, Reynolds number, etc, etc. That doesn't work on a boat because the boat shares different frictions with air and water.
Some power boats fool around with similar theories and stepped hulls. But boats that are paddled or even sailed don't have enough forward thrust in relation to surface area and fluid resistence to make these theories effective. A guy did it with a baseball bat with very little gain.
Anyway... smoother is better for the boats we use.
Opposing that is the golf-ball dimple effect to reduce drag but that involves Bernoulli principal, fluid mechanics, boundary layers, Reynolds number, etc, etc. That doesn't work on a boat because the boat shares different frictions with air and water.
Some power boats fool around with similar theories and stepped hulls. But boats that are paddled or even sailed don't have enough forward thrust in relation to surface area and fluid resistence to make these theories effective. A guy did it with a baseball bat with very little gain.
Anyway... smoother is better for the boats we use.
Anything you do to change the surface tension of the water as it relates to the surface of the boat will change the friction. Of course it's more noticeable at higher speeds - which us geezers rarely achieve.
While waxing won't fill in the scratches, it will make the flat parts slicker
Ultimately what you're looking for is a surface that water will not wet but will bead up on. Put a drop of water on your car hood then wax it and reapply the drop of water. That drop will bead up more on the waxed part than the unwaxed part. You've made it harder to wet the surface and reduced the friction
A similar effect is a non-stick teflon lined skillet - notice how water won't wet it out and stuff won't stick to it. Or consider how Rain-X works on your winshield
While waxing won't fill in the scratches, it will make the flat parts slicker
Ultimately what you're looking for is a surface that water will not wet but will bead up on. Put a drop of water on your car hood then wax it and reapply the drop of water. That drop will bead up more on the waxed part than the unwaxed part. You've made it harder to wet the surface and reduced the friction
A similar effect is a non-stick teflon lined skillet - notice how water won't wet it out and stuff won't stick to it. Or consider how Rain-X works on your winshield
Jack, I never tried any kind of coating on my boats. I remember reading that world class yacht racers differ in the surface prep of their hulls. Some swear by waxing or using other coatings and some are convinced that very light sanding with fine grit sandpaper is the way to go. A sanded graphite/epoxy layer on the bottom does make for a slippery ride.
Joey
Joey
It's interesting to note that animals, like whales and dolphins, seem to have a lower coefficient of friction than any boat of any shape. I'm sure there has been some research on this for design of boat hulls, particularly submarines, but I've never seen any results. I wonder if the actual surface of the skin is responsible? Or maybe it's because the skin flexes (blubber underneath) when small pressure waves slide across it, and this flexure somehow reduces drag? Or, a combination?
ya jack put fur on your boat like a seal. i think you have somethig going. no i think sarah palin has don that. forget, keith
A lady in fur is better than a boat in fur, I'm pretty sure. But, whales aren't very furry, I don't think? Maybe we need to talk this over with an adult beverage in hand.
The movement of fish through the water is very interesting to me. Between human contestants a .1 % increase in speed is major acheivement. The fastest fish have as much as SEVERAL HUNDRED percent edge in speed on us humans. I've read a lot on the subject looking for some of the secrets. No conclusive evidence but my pet hunch is that a fish's sinuous movements somehow "curve around" the water's resistance and shed it's effect. Think of a snake going back and forth between the pickets of a fence without actually running into the fence. The fence can offer no resistance to the snake if hardly touches it. Just a hunch.
Joey
Joey
It's interesting to look at the hydrodynamics. We have a rigid hull, and it's difficult to figure drag etc. on those. A moving, flexing hull (fish's body) presents problems several orders of magnitude more, and they change in an instant and cannot be held constant for study.
Fish have slime, and that has to be part of it. I agree, Joey; I also think their movement is part of it. As a fish flexes, major portions of its body are pushing back - at least in some degree - on the water. A human swimmer has to drag his arms out of the water, partly creating back force and the rest is just drag. A fish makes propulsion no matter how it moves.
Fish have slime, and that has to be part of it. I agree, Joey; I also think their movement is part of it. As a fish flexes, major portions of its body are pushing back - at least in some degree - on the water. A human swimmer has to drag his arms out of the water, partly creating back force and the rest is just drag. A fish makes propulsion no matter how it moves.