Shaving Your Kayak??? - Canoeing / Kayaking

Table of Contents

Shaving Your Kayak??? - Dgremlin - Dec-02-12 3:08 PM
- Why bother? - gstamer - Dec-02-12 3:27 PM
- Why? - radskierman - Dec-02-12 4:53 PM
  - Sure - shiraz627 - Dec-02-12 6:44 PM
- There still isn't much evidence about - g2d - Dec-02-12 7:11 PM
  - Have you guys ever sailed a dirty hull - onnopaddle - Dec-02-12 8:17 PM
    - melting is better - Dr_Disco - Dec-02-12 8:53 PM
    - I thought my fuzzy kayak and c-1 were - g2d - Dec-03-12 11:17 AM
- how do I repair burn holes in my hull - ShadyClip - Dec-02-12 9:07 PM
- Completely utterly FALSE - willi_h2o - Dec-02-12 9:14 PM
  - Micro grooves - carldelo - Dec-03-12 5:49 PM
- If you decide to go ahead ... - Bob_d - Dec-02-12 9:45 PM
  - I have two Scupper Pros here - onnopaddle - Dec-02-12 11:30 PM
    - Clean and smooth - willi_h2o - Dec-03-12 9:58 AM
      - wax? - harry0244 - Dec-04-12 7:23 PM
- I have, but don't now - Peter-CA - Dec-03-12 1:04 PM
- I'd Save the Shavings - clydehedlund - Dec-03-12 1:42 PM
- my question - radiomix - Dec-03-12 2:18 PM
  - shaving - poleplant - Dec-03-12 2:43 PM
- Shave your head - jimyaker - Dec-03-12 2:56 PM
  - Shaving - krash - Dec-04-12 9:34 AM
  - That was truely funny. - kayakboy - Dec-04-12 6:41 PM
- don't shave it - Pirateoverforty - Dec-04-12 9:51 AM

Messages in this Topic

  Why bother?
  Posted by: gstamer on Dec-02-12 3:27 PM (EST)

-- Last Updated: Dec-02-12 3:48 PM EST --

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?

Greg Stamer

  Why?
  Posted by: radskierman on Dec-02-12 4:53 PM (EST)

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?

  Sure
  Posted by: shiraz627 on Dec-02-12 6:44 PM (EST)

The new pivoting four blade Gillette's cartridges along with the Gel cream makes the boat fly!

  There still isn't much evidence about
  Posted by: g2d on Dec-02-12 7:11 PM (EST)

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
  Posted by: onnopaddle on Dec-02-12 8:17 PM (EST)

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
  Posted by: Dr_Disco on Dec-02-12 8:53 PM (EST)

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".

  I thought my fuzzy kayak and c-1 were
  Posted by: g2d on Dec-03-12 11:17 AM (EST)

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.

  how do I repair burn holes in my hull
  Posted by: ShadyClip on Dec-02-12 9:07 PM (EST)

D'oh!!!

  Completely utterly FALSE
  Posted by: willi_h2o on Dec-02-12 9:14 PM (EST)

-- Last Updated: Dec-02-12 9:20 PM EST --

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.

  Micro grooves
  Posted by: carldelo on Dec-03-12 5:49 PM (EST)

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.

  If you decide to go ahead ...
  Posted by: Bob_d on Dec-02-12 9:45 PM (EST)

.. and shave it be careful not to cut too deep.

It's almost impossible to get little bits of tissue paper to stick on a plastic kayak hull.

  I have two Scupper Pros here
  Posted by: onnopaddle on Dec-02-12 11:30 PM (EST)

both weigh the same. Hulls still stiff and original shape. ... One is hammered and totally gouged up in every direction on the entire hull ..I.E. like it wallowed on oyster beds. In this case it was lava + other razor sharp sea stuff. The other is relatively untouched ... Its pretty EZ to tell which one is which by the glide and effort it takes to move them through the water.

I guess some people might not notice this but others will.

If you have a rough hull or one with huge print through from using roving for example ... smoothing it out will make it faster. One might not 'notice it' but it WILL lower drag.

"If you entered the boat in an actual sanctioned race,you would only get disqualified by the judges anyways."

Willie, I gotta figure you are talking about the 3M stuff here 'cause wetsanding is not gonna get anyone DQed in any race.

  Clean and smooth
  Posted by: willi_h2o on Dec-03-12 9:58 AM (EST)

I would never wetsand a kayak, but I agree that
a smooth, clean, pristine, out of the mold,
kayak hull is the way to go.
No waxes, no goop, no nothing, applied to hull.

  wax?
  Posted by: harry0244 on Dec-04-12 7:23 PM (EST)

I waxed my plastic boat. I do not notice any difference paddling, but mud from various launch and landing sites comes off faster.

  I have, but don't now
  Posted by: Peter-CA on Dec-03-12 1:04 PM (EST)

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
  Posted by: clydehedlund on Dec-03-12 1:42 PM (EST)

For filling in any large gorges and holes.

  my question
  Posted by: radiomix on Dec-03-12 2:18 PM (EST)

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?

Ryan L.

  shaving
  Posted by: poleplant on Dec-03-12 2:43 PM (EST)

A 50 lb tub of Nair did it for me.

  Shave your head
  Posted by: jimyaker on Dec-03-12 2:56 PM (EST)

You'd probably notice more of a difference if you shave your head. All that hair in the wind is slowing you down too. ;-)

  Shaving
  Posted by: krash on Dec-04-12 9:34 AM (EST)

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.

  That was truely funny.
  Posted by: kayakboy on Dec-04-12 6:41 PM (EST)

nt

  don't shave it
  Posted by: Pirateoverforty on Dec-04-12 9:51 AM (EST)

Just tell everyone it's a European kayak

	Why bother? Posted by: gstamer on Dec-02-12 3:27 PM (EST)
	-- Last Updated: Dec-02-12 3:48 PM EST -- 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? Greg Stamer

	Why? Posted by: radskierman on Dec-02-12 4:53 PM (EST)
	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?

	Sure Posted by: shiraz627 on Dec-02-12 6:44 PM (EST)
	The new pivoting four blade Gillette's cartridges along with the Gel cream makes the boat fly!

	There still isn't much evidence about Posted by: g2d on Dec-02-12 7:11 PM (EST)
	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 Posted by: onnopaddle on Dec-02-12 8:17 PM (EST)
	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 Posted by: Dr_Disco on Dec-02-12 8:53 PM (EST)
	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".

	I thought my fuzzy kayak and c-1 were Posted by: g2d on Dec-03-12 11:17 AM (EST)
	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.

	how do I repair burn holes in my hull Posted by: ShadyClip on Dec-02-12 9:07 PM (EST)
	D'oh!!!

	Completely utterly FALSE Posted by: willi_h2o on Dec-02-12 9:14 PM (EST)
	-- Last Updated: Dec-02-12 9:20 PM EST -- 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.

	Micro grooves Posted by: carldelo on Dec-03-12 5:49 PM (EST)
	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.

	If you decide to go ahead ... Posted by: Bob_d on Dec-02-12 9:45 PM (EST)
	.. and shave it be careful not to cut too deep. It's almost impossible to get little bits of tissue paper to stick on a plastic kayak hull.

	I have two Scupper Pros here Posted by: onnopaddle on Dec-02-12 11:30 PM (EST)
	both weigh the same. Hulls still stiff and original shape. ... One is hammered and totally gouged up in every direction on the entire hull ..I.E. like it wallowed on oyster beds. In this case it was lava + other razor sharp sea stuff. The other is relatively untouched ... Its pretty EZ to tell which one is which by the glide and effort it takes to move them through the water. I guess some people might not notice this but others will. If you have a rough hull or one with huge print through from using roving for example ... smoothing it out will make it faster. One might not 'notice it' but it WILL lower drag. "If you entered the boat in an actual sanctioned race,you would only get disqualified by the judges anyways." Willie, I gotta figure you are talking about the 3M stuff here 'cause wetsanding is not gonna get anyone DQed in any race.

	Clean and smooth Posted by: willi_h2o on Dec-03-12 9:58 AM (EST)
	I would never wetsand a kayak, but I agree that a smooth, clean, pristine, out of the mold, kayak hull is the way to go. No waxes, no goop, no nothing, applied to hull.

	wax? Posted by: harry0244 on Dec-04-12 7:23 PM (EST)
	I waxed my plastic boat. I do not notice any difference paddling, but mud from various launch and landing sites comes off faster.

	I have, but don't now Posted by: Peter-CA on Dec-03-12 1:04 PM (EST)
	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 Posted by: clydehedlund on Dec-03-12 1:42 PM (EST)
	For filling in any large gorges and holes.

	my question Posted by: radiomix on Dec-03-12 2:18 PM (EST)
	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? Ryan L.

	shaving Posted by: poleplant on Dec-03-12 2:43 PM (EST)
	A 50 lb tub of Nair did it for me.

	Shave your head Posted by: jimyaker on Dec-03-12 2:56 PM (EST)
	You'd probably notice more of a difference if you shave your head. All that hair in the wind is slowing you down too. ;-)

	Shaving Posted by: krash on Dec-04-12 9:34 AM (EST)
	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.

	That was truely funny. Posted by: kayakboy on Dec-04-12 6:41 PM (EST)
	nt

	don't shave it Posted by: Pirateoverforty on Dec-04-12 9:51 AM (EST)
	Just tell everyone it's a European kayak