Ignoramus26696 wrote:

I made this boat trailer guide:

http://igor.chudov.com/projects/Trailer-Guide/

I need it because we frequently go boating on a river with very strong
current, which makes keeping the boat aligned over the trailer
difficult during retrieval.

The base is made of 3/8" thick hot rolled mild steel. The bolts are
half inch bolts.

How do I paint it to prevent corrosion?

Best solution is hot-dip galvanizing. Watch out for minimum order, though -- my
galvanizer charges $75 to do one toothpick up to about 200 pounds. I have never
tried cold galvanizing. Some hardy souls on this NG might consider melting up
some zinc in a furnace and doing DIY hot-dip galvanizing on this part because
it's small enough to maybe fit into a crucible. But I wouldn't.

If you're just going to paint it, disassemble it and clean it with solvent
(paint thinner) and blow it dry, then give the non-galvanized parts (not
counting the bolts, those are stainless, right?) a coat of ruddy red primer.
This coat should be perfect, no little pinholes. Maybe 2 coats. Then topcoat it
with any quality enamel to the color you like -- it's the red primer that does
most of the antirust work.

A part this small wouldn't be too much trouble to derust and repaint every
decade or so. Navy ships are made of steel. Perhaps you've heard of the old Navy
aphorism: paint the whole ship one end to the other, then start over again. They
just use good paint and a whole lot of it.

Grant