If I had a dollar for every time I've seen questions how to get rid of these yellow water marks that stain our beautiful Cobalt boats - I could take most of you out for a very nice lunch - with drinks!! What I have used with much success is a solution of "Iron Out" in a garden sprayer. I mix up about 1.5 gallons - spray on and then hose off - you literally will see the color fall off. I haven't had a bit of problem with the finish/wax etc. I'm very anal about the boat maintenance and this really is easy to use and very inexpensive. All the best and be safe! 3pointstar
Great tip, 3pointstar! Thank you for sharing with us. Another product that works great for me is Slimy Grimy. I like it because it's non-toxic and doesn't damage the metal on my trailer the way regular hull cleaner can. https://www.amazon.com/Slimy-Grimy-Granular-Tub-1-Pound/dp/B0000AXNLW
In have used Bar Keeper's friend on a brush, leave on for about a minute. The Oxalic acid works wonders. Need to re-wax after application.
Agree, oxalic acid works the best. I had to switch to Slimy Grimy because the acid etched the bare metal on my trailer. I'll give Bar Keepers friend a try.
Toilet bowl cleaner, we use The Works brand that you can find in your local dollar store. Mix it up with some water in a hand held pump sprayer, spray it on and hose it off. The bottom will be back to bright white without scrubbing. Just don't leave it on too long before you hose it off and wear a mask and eye protection.