Hull wax or sandpaper

[suzuki115]

Have a sailing friend who tells me he sands the hull of his Cat with 600 grit sandpaper. He tells me it is his "racing secret". Says the rough hull surface holds water so that you are running on a water to water surface which is less friction vs a water to waxed surface. Is there any truth to this or has his "racing secret" been slowing him down all these years?

 

[Bob_VT]

Re: Hull wax or sandpaper

It's true! The sanding creates a disruptive surface which holds the hull away from the water better than wax. Racing boats (mostly outboards) have been doing this for years. The Fountain boat company (very high end high performance boats) was speed testing a hull and the company actually drilled holes in the hull to create a disruptive surface. Last year I lightly sanded my tri-hull (85 hp Johnson) and picked up 1 1/2 mph on gps.<br /><br />Read this post for additional information:<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=003621 <br /><br />Bob

 

[crab bait]

Re: Hull wax or sandpaper

ther's a post i posted not long ago.. it was about a product from west marine called guide side or sea slide or somthin' i forget ... but this stuff is clear ..you paint on.. lasts 100,ooo sea miles an reduces gas consum. buy 20 %.. causes a water on water hydropontic action...

 

[SCO]

Re: Hull wax or sandpaper

Shark skin is rough like sandpaper( was used as sandpaper in old days). As hydrodynamic as they are, if rough skin was a detriment, I imagine it would not be rough, but who knows. Also, maybe for a different reason and a comparison between air and water, dimpled golf balls go farther than smooth ones. The dimples produce a turbulent boundry layer that stays attached further around the back side, pressurizing the back better, and reducing the net drag.