Cleaning Product Recommendation

[boatnamesue]

The underside of my hull has become...well, not sure what you'd call it....grim stained?  The picture below isn't meant to show you the grim I'm speaking of, rather just to point out the area needing a good cleaning.  I've tried soft scrub and liquid comet (both applied gently).  Neither did the trick.  About a year ago while I was at the wash down station at the boat ramp, this guy showed me a product he uses.  He simply wiped with one stroke and the discoloration was gone.  But for the life of me I can't recall the name of the product. 

Recommendations?

[RickK]

Try Greased Lighting.

[Capt. Bill]

I use a powder made by Boatlife. Its called fiberglass powder cleaner & stain remover, comes in a yellow, black and white container. Best stuff I've ever used, takes off everything. It does leave a chalky residue  afterward though.  To combat that on the hull I use a deep cleaning liquid wax called Maxi Wax.  It takes the powder residue off and brings the hull up to a showroom shine. When I use the powder to clean the deck I just rinse it with water. Any leftover residue gets hidden in the no skid and washes the out next time I take her out. 

[boatnamesue]

Ok, thanks guys.

[wingtime]

On off hull cleaner will take it off right before your eyes. Remember gel coat is porous and will stain easily. Be careful that stuff is acid.

[Capt. Bob]

Still another way to skin the cat.

Oxalic acid aka Rust Aid in HD or Lowes also works.

Rinse it off the trailer asap.

[boatnamesue]

Still another way to skin the cat.

Oxalic acid aka Rust Aid in HD or Lowes also works.

Rinse it off the trailer asap.

Thanks Bob.  Curious, I wonder if a standard toilet bowl cleaner would also do the job.