What is the best chemical to use on a boat to get the scum line off it?

Question

im interested in buying a boat and it looks like it sat in fresh water for a long period of time and theres a scum line on it that looks pretty bad

is there somthing that will not hurt the gelcoat and make her shine like new

ive heard to use muratic acid on it but is this true????

Answer 1

I agree with duck foo.

Answer 2

oxalic acid works but you must let it dry before you wash it off

hope this helps

Answer 3

CAREFUL use of muratic acid can do it if they are hard stains.  Toilet bowl cleaner can also help.  BOTH of these are dangerous to handle - use precautions like heavy rubber gloves, protective clothing and eyewear and a respirator.

Be careful if the gel coat has gotten porous - the toilet bowl cleaner can stain and be hard to remove itself.

I would start with ordinary pressure washing and some detergent to get as much off as possible first, but you've likely done so to get to this question.

Answer 4

Try a product made by "Boat Armor" called Hull Cleaner.  It is an acid so be careful.  

You can buy it at West Marine or Boat US.  My boat sits in a dirty lake all summer and I pull it out and wipe it on carefully.  The scum melts away.

Answer 5

I would try an automotive cleaner like purple cleaner or that mean green. The waterline has all the oils that float on top of the water and sometimes a degreaser is needed to break it down. Try a bit at a not conspicuous place if it does not work as desired.

Answer 6

a Product called "CLR"..which removes "Calcium, lime, Rust"

..stuff works great..

Answer 7

Elbow Grease.  That line will not come off with any thing that I know of.  I worked as a mate of a off shore fishing boat for two summers, and I can tell you all that gets it off is a soogie pad and hard work.

Answer 8

my hot water pressure washer works well, i usually do it before it sits though

Answer 9

bleach

Answer 10

Power washing and Lime-Away has always worked for me.

Answer 11

Washing the boat with the wrong product can shorten the life of the paint and/or gelcoat. Only mild soaps designed for boat cleaning like Orpine or boat soap from Allied Marine ship store should be used. If areas have soot from the engines or stains around through hull fittings (A/C outlets, cooling water outlets,ect.) find a product at your local marine supplier that is made for that purpose. Soft Scrub should not be used on these areas as it is abrasive and will harm the finish.