Recently I overheard a fellow kayaker say he was going to shave his “plastic” kayak. I didn’t pay much attention until I heard someone else mention it also. He said if you take a regular BIC razor and shave all the small nicks and scratches on the bottom it will make it smoother in the water. Do people actually do this and if so, does it really help much?
I don't really get the point. Maybe for racing, I could justify any minute performance gain, if any, but then I wouldn't be using a plastic hull for racing, anyway. If I wasn't racing, I wouldn't care. As always, YMMV.
Of course, if it makes you feel better about your kayak, and you like to keep your gear well-maintained, why not?
Unless your racing, in which case you most likely are not in a plastic boat, why bother? I paddle for exercise as much as anything, so a little extra drag is a good thing. My bottom is really rough, with gouges and every thing else and I really don’t care. In fact, my ability to just run it up on shore and not have to worry about it is probably half the reason my fiberglass boat gets paddled so little. As in 3 paddles out of my last 190 paddles has been in my fiberglass boat! Want to buy a very little used Assateague reasonable?
The new pivoting four blade Gillette’s cartridges along with the Gel cream makes the boat fly!
There still isn’t much evidence about
how much roughness affects plastic boats, smooth or scarred. Plastic boats don’t enter serious races, they don’t carry out missions for the Navy, and so there isn’t much motivation for towing plastic boats in float tanks to find out the truth.
Have you guys ever sailed a dirty hull
then cleaned it and sailed again ? Night and day difference. Plastic boats are more effected than composite BC the ‘hairs’ stick out into flow. A few scratches cleaned up not gonna notice, but if your boat looks like it wallowed across oyster beds for a week then it will be noticeably improved in speed and glide by shaving or melting this stuff off.
melting is better
if you really want to do it. Get a torch and heat a metal rod (held with a firm grip tool). Carefully move the heated rod over the surface of the hairy plastic hull to fill scratches and remove protrusions. Don’t get burnt and don’t get the rod too hot. And don’t post here about “how do I repair burn holes in my hull”.
how do I repair burn holes in my hull
Completely utterly FALSE
You'll never ever notice the speed effect
unless you have 100th of a second precision timing
and are in Olympic caliber physical condition.
Generally speaking, a clean smooth hull is good.
People have been playing with smooth vs rough
surfaces for a very long time now.
Myths unfortunately remain in the kayak world.
A micro-grooved adhesive backed plastic film from 3M
was tried out by Greg Barton in the semifinals of the
1986 World Championships in Montreal.
Apparently the grooves need to be very carefully
aligned so they are parallel with the flow of water
over the surface. The size of the grooves was matched
to the density of water and the speed of travel so
that the grooves dampen the turbulence of the water
as the flow detaches from the hull.
This leads up to a popular internet myth
in the kayak world.
The crazy idea of hand sanding scratches lengthwise
down the entire boat hull to make your boat go faster.
Don't do it folks ! You'll never get the robotic
accuracy needed for perfectly straight and parallel
lines down the entire length of your hull.
If you entered the boat in an actual sanctioned race,
you would only get disqualified by the judges anyways.
I thought my fuzzy kayak and c-1 were
faster after I smoothed and recoated them, but I just don’t trust my own subjective impression. Somewhere, there’s got to be some tow tank data.
I have, but don’t now
I have shaved boats in the past, but don’t now. Didn’t feel a difference between shaved and un-shaved.
I’d Save the Shavings
For filling in any large gorges and holes.
Would be. If one cared enough to shave ones plastic boat, why does one have all these scratches, and why does one race a plastic boat?
A 50 lb tub of Nair did it for me.
Shave your head
You’d probably notice more of a difference if you shave your head. All that hair in the wind is slowing you down too.
I saw some experimental and simulation results of flow in the micro grooves. Interesting, and yes they have to be tailored to the velocity and flow direction to have any useful effect. It’s not really about detaching flow, the grooves actually modify the flow structure at the wall, and reduce the overall viscous friction production.
Even if the grooves were 100% straight down the length of the hull, or even better, if they were somehow aligned with the mean flow direction at every point on the hull, the truth is the direction of the flow over a kayak hull changes enough while paddling to make the grooves effectively out of alignment most of the time.
Pat is right that smoothing a hull will reduce drag - the amount depends on how bad it was before and after, obviously. And Willi is right that just smooth is best, no additives, wax, etc.
Don’t shave my hull with a shaving razor…
Have a Scupper-Pro that gets pretty scratched and niked up from use, launch sites are not all smoothe, shallow water fishing has rock and coral contatc, and oyester beds in unexpected places.
I have cut my self more than once loading/unloading or carrying the kayak from stand to car or roof to water on the jagged little curleys.
I do take a safety razor and shave the curleys off every once in a while just for visual affect, never thought of it helping performance as they go in all directions, and don’t notice the differenct but I’m not racing anyone from place to place. No more of unectected cuts do to running your hand or leg across the hull.
I also once stole my daughters flat hair iron, busted it into 2 parts and used the hot flat iron to reshape and flatten out the jaggiies and curleys… did teh the trick also… I guess you could use a high enough heat to melt the jaggies and curleys back into the hull but I’ve never tried it and would be skeptical of getting the roto plastic hull that hot.
don’t shave it
Just tell everyone it’s a European kayak
That was truely funny.