I read somewhere about how applying a coat of marine grade polish to your OC-1 hull is supposed to make it perform better. Huh, really? I understand a coat of polish may be a way to care for and protect my boat, but how do folks support the claims that adding a coat of polish or "magic spray" will actually improve it's performance? Note, I said it's (the boats) performance, not your performance. =)
Submitted by King of Kailua on Wed, 10/28/2009 - 12:38pm
NO.
#1 Wed, 10/28/2009 - 1:35pm
I figure if teflon is illegal in the olympics it must be doing something good. Maybe its just a mental thing. I just like the way the boat is when its slicker than eel shit!
#2 Wed, 10/28/2009 - 2:35pm
If you believe it has an effect, then it has one...
#3 Wed, 10/28/2009 - 3:40pm
astroglide works pretty good so i hear.. definitely improved performance.
#4 Wed, 10/28/2009 - 10:32pm
Teflon is bad for the fish...
#5 Thu, 10/29/2009 - 5:05am
depends what waterspeed you are running at. certain paints have scientifically proven to achieve laminar flow. i spent a long time working through this theory with America's Cup boat designers and painters. http://en.wikipedia.org/wiki/Laminar_flow. i dont remember the effective speed range for laminar flow but i remember painting my canoe it becoming heavier and only really lifting on really fast bumps - otherwise the canoe was heavier.
#6 Thu, 10/29/2009 - 7:52am
I've also heard of people scuffing up their hulls with a really fine sandpaper claiming that this improves their boats (again, not there own!) performance. It's interesting to me that people are trying things on both sides of the hull smoothness spectrum with the same claimed results.
#7 Thu, 10/29/2009 - 9:57am
The people who are scuffing the nose of their boats are trying to trip the boundary layer turbulent to reduce drag caused by boundary layer separation.
A few links:
http://en.wikipedia.org/wiki/Boundary_layer_separation
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml
There's a pretty cool picture in most introductory fluid mechanics textbooks of a bowling ball being dropped into water with a smooth nose and roughness patch on the nose. The drag reduction due to the roughness patch is on the order of 50%.
In general, the smoother the surface, the less drag. So if your canoe hull is beat up and has a lot of scratches, dings and dirt on it, then polishing will probably help you out a little. Plus you get to spend some quality time off the water with your canoe.
#8 Thu, 10/29/2009 - 10:33am
Now there's a paddler who firmly belives that Turtle Wax makes his surfboards and canoes faster, even though I keep telling him that the stuff re-formulates in salt water to actually make the boat slower.
#9 Thu, 10/29/2009 - 10:38am
If all of the expert paddler didn't mention it (polishing hull) in the thread "How to paddle fast"
http://www.ocpaddler.com/forum/2009/how_paddle_fast
then you know it doesn't help you-otherwise they would have mentioned it.
Now they didn't mention weed or beer either, and I know...............................
I've confused myself-maybe it does make you faster.
#10 Thu, 10/29/2009 - 10:47am
There's obviously something to be said for scuffing up your bowling ball, or polishing your yacht, but if you want something a little more similar to our sport, you may want to check this out: http://www.epickayaks.com/news/news/to-wax-or-not-to-wax
#11 Thu, 10/29/2009 - 1:20pm
Greg Barton said:
Clean your boat regularly.
A few notes on Goto's link:
Exactly how a drag reducing polymer works isn't truly understood and is still an area of active research. The Navy has supported research in this area for several years (for obvious and not so obvious reasons). A very simple explanation that leaves out the how is the polymer organizes the flow in a similar manner to the riblet material mentioned in the article. The viscosity change mentioned by Barton doesn't account for all of the drag reduction created by the compound nor some of the more interesting changes in the flow researchers have noticed with these polymers.
I think it was in Nature (the scientific journal) a couple of years ago there was an article on shark skin and how it interacts with the flow to reduce drag, making sharks both very fast and very efficient swimmers. Again, no one understands the underlying physics of how this works. This is what the riblet material was potentially doing. The main difference is a shark changes shape relative to the flow while a boat doesn't.
The fancy speed suits that swimmers wear are another attempt at the same idea, reduce drag by creating a smooth surface. The researcher (I believe it was at NASA where the testing was done) that tested all the materials for these suits summed up his research by saying "The smoother the better." Most boats are smooth enough you won't ever see a difference, but that's no excuse not to protect your investment by keeping it clean.
#12 Thu, 10/29/2009 - 1:43pm
The basic issue of skin friction resisitance (vs. wavemaking resistance) has to do with which surfaces interact. On one hand, generally smooth is faster than bumpy, dirty, dented, or covered with sap drops, so having a clean, smooth hull is better than a dirty, bumpy hull. However, most waxes and coatings are hydrophobic, meaning water is repelled by it and beads up. The surface interaction is water on wax. This does not promote laminar flow. The fastest surface combination is water on water. Wetsanding a hull in the direction of travel actually causes a microscopically thin layer of water to adhere to the bottom of the boat. Hence, you get water on water, the lowest source of friction possible.
#13 Sat, 10/31/2009 - 11:01am
It's a basic principle of fluid mechanics that the water immediately in contact with the surface will not be moving relative to the surface. This is known as the no-slip condition and is a rather important concept since without it viscosity really wouldn't have a way to remove energy from the flow (i.e. there would be no velocity gradient to generate viscous forces).
I also really doubt that any flow past a hull will ever be laminar. It might be smoothly varying, attached and many other things, but not laminar.
#14 Sat, 10/31/2009 - 1:01pm
Laminar flow could exist for perhaps the first 10-12% of the hulls wetted area, if the entry is fine enough......this according to those who have actually seen the thing happening.
After this the flow becomes turbulent.
#15 Sat, 10/31/2009 - 3:17pm
there was an amazing video on the Discovery channel TV show Time warp, They use high speed cameras to see what is happening to everyday objects, They had one where they dropped a cue ball into a tank of water, One view had a normal ball, when it hit the water it made a huge splash pulling air deep into the tank, the second view had the same ball with a thin coating on it, The ball made almost no splash. The difference was amazing. The same principals would apply to a hull, and the release of water.
#16 Wed, 11/04/2009 - 5:46am
Now how many of those high tech "Fast Skin" swim suits do I need to buy to cover the hull of my canoe? Or where do they sell the material so I can start bonding it to the hull now?
#17 Wed, 11/04/2009 - 2:30pm
Gotta remember though, those swimmers are trying to take off 100ths of seconds and if lucky 10ths with their speed suits.
I don't remember losing many races by fractions of a second ;o)
#18 Wed, 11/04/2009 - 9:04pm
Actually just talked to my advisor about the sanding issue as it pertains to sailing, and it's not exactly what I thought. What they are actually trying to do is control where the boundary layer becomes turbulent so as to minimize separation and form drag. Anyway, this doesn't change the concept of smoother is better for paddlers. Try whatever you want to go faster, but the paddler is going to make the biggest difference so that's probably your best investment.
#19 Mon, 11/09/2009 - 10:49am
In my head I keep hearing Dave Chapelle- " Smooth as eggs..." Like you said, try whatever...
#20 Tue, 11/10/2009 - 1:50pm