There was a project done where they towed a sailboat with an average bottom over a measured mile under ideal calm conditions. They took the boat out of the water and sanded the bottom smooth (nothing fancy) and then put it back in the water and towed it under the same conditions and the result was 24 seconds faster, so I believe it does make a difference and smother is faster. The lighter the conditions the more difference it makes. With Black Widow I believe the burnishing also helps activate the biocides which enhances the anti fouling properties of the paint.
When you burnish do you wet sand first or are you just burnishing over a rolled-on surface? If wet sanding or sanding the painted surface what grit are you using? Rod Stright C&C 99 ________________________________ From: CHARLES SCHEAFFER via CnC-List Sent: Friday, April 4, 2025 12:08 AM To: Stus-List Cc: CHARLES SCHEAFFER Subject: Stus-List Re: Sanding/burnishing hard bottom paint Interesting thread as I plan to switch bottom paint to Black Widow this spring and considered the burnishing option. I am convinced burnishing makes the hull faster, but not worth the extra money and labor for my situation. I decided to not paint a third coat and save the money for paint and hours of labor burnishing, also. I'll paint two coats and get them as smooth as possible and call it a day. Paint is expensive and it's not good for the environment to sand it off. I'm convinced a burnished hull is faster in light winds, as it offers less resistance. This is less of a factor in good wind. And in strong win, if you are well powered up, you should be making hullspeed, and that's all you can do anyway. To test this theory, I can imagine painting a smaller vessel, say a kayak, and set it in a river with person in it, and a simple fish scale tied between the bow and a tree, and measure the resistance, "paint unburnished" vs "paint burnished". That's my two cents. Chuck Scheaffer, Resolute 1989 C&C 34R, Annapolis On 04/03/2025 10:41 PM EDT Marek Dziedzic via CnC-List <cnc-list@cnc-list.com> wrote: It is more than just articles. There are a lot of actual lab tests. I would gladly participate in your bike test. I use 28 mm with 80 psi. Btw. I switched from 22 mm at 110 psi, and I am faster (Strava supports that claim). And I am a clone of myself (if anything, I should be slower as I moved to the next age category). Marek 1994 C270 Legato Ottawa (should I include the bike model?) From: David Knecht via CnC-List <cnc-list@cnc-list.com> Sent: Thursday, April 3, 2025 5:58 PM To: CnC CnC discussion list <cnc-list@cnc-list.com> Cc: David Knecht <davidakne...@gmail.com> Subject: Stus-List Re: Sanding/burnishing hard bottom paint Unlike boat bottom smoothness, there are lots of articles out there on tire pressure and speed (with data). I would take you up on your race offer, but to do it right, we need to clone one of us and put one clone on your bike (21 mm tires at 120 psi) and one clone on my bike (28-32 mm tires at 80 psi). Dave Myths Debunked: Higher Tire Pressure is NOT Faster<https://www.renehersecycles.com/myth-16-higher-tire-pressure-is-faster/?srsltid=AfmBOork2tEEWJzCXYhjHdtya_q1DZZEJfm5CdFQ4lk7ST0UVoCYRU6r> renehersecycles.com<https://www.renehersecycles.com/myth-16-higher-tire-pressure-is-faster/?srsltid=AfmBOork2tEEWJzCXYhjHdtya_q1DZZEJfm5CdFQ4lk7ST0UVoCYRU6r> [cid:image001.png@01DBA4E9.92B2FAE0]<https://www.renehersecycles.com/myth-16-higher-tire-pressure-is-faster/?srsltid=AfmBOork2tEEWJzCXYhjHdtya_q1DZZEJfm5CdFQ4lk7ST0UVoCYRU6r> David Knecht Emeritus Rear Commodore/Thames Yacht Club Emeritus Professor/University of Connecticut Basketball Capital of the World Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
