Sanding a lower unit for speed
 

Hey peeps do you have a opinion for a finish on a raw aluminum lower unit. what will actually work the best to make it fast? I have heard 600, 1200 even 80 grit on an orbital sander.. What is the best??

Did you already get them blue printed?

I keep mine sanded, i started with 60 then 80 then 120 and finally 220. I keep them shiney with a 3M scotchbrite red pad and wd40. being as i have really done nothing other than make them satin finish, other than looking good i couldnt tell ya. :)

Yes they are as strait as can be without making them too thin on the fin. Just tryng to figure out what causes less ressistance. I think 80 on an orbital works for sail boat botoms but i don't know what is best for a lower unit. I used 600 on mine. And a little wd to get the limescale off

I sanded with the flow of the water. 600 wet I think

I use a phosphoric acid solution to keep it bright.

Imron.

Paint the bottoms of the tabs with it also.

Orbital sander with 120-180 works best. Shiney is slow

so mine are sanded with 600 now. You're saying hit it with a D A and some 180 and I will go faster? Is it like 1 mile per hour or will I even notice it? Thank you for answering my question

Im very curious to a real world answer on this. Guys spend hours buffing and waxing hull running surfaces but shiny is slow on a lower unit?

For speed buffing the bottom of the hull is worse thing u can do. For speed sand the back 10 ft. Of the hull on a outward 45 degree angle with a flatboard and 180. It will areate hull