Receive this question weekly from Boat Bling customers. I wish I would have paid more attention to chemistry in high school because I'd be able to keep up with the chemists we work with LOL
Interior cleaners and soaps such as Totally Awesome, Vinyl Sauce, Malco, etc are usually alkaline (high pH) in nature which helps them create suds when mixed with water. To remove mineral deposits from the hull you need something acidic (low pH)
We stay far away from the harsh chemicals required to accomplish such a deep clean but our suggestion is to acid wash with a dilution of muriatic (pool) acid. Gelcoat is porous so the minerals and sediment embed themselves into the surface and become very difficult to remove. Might as well do the entire hull while you're at it which will remove any old wax residue and grime so you can start fresh. Follow up with liberal amounts of water to remove and neutralize remaining acid from boat and especially trailer. Be careful throughout the process and always use hand/eye protection. Muriatic acid is no joke.
After she's all cleaned up, put on a good coat (or 2, or 3) of polymer wax sealant. Carnuba waxes typically offer great shine with their oil base but offer minimal protection once dunked in water. You want to create a barrier on the hull especially the underside so the minerals never have a chance to get to bare gelcoat. The more time you spend protecting the gel, the less work to remove water spots and stains. Once protected, stay away from vinegar and strong spot removers unless you want to rewax and begin the cycle all over again. (Stop reading if you are offended by shameless plugs lol) Hot Sauce was developed around it's mineral deposit removing abilities while maintaining wax protection so it's safe to use on waxed surfaces and its sealant properties compliment the wax coat.
Last edited by Fourspeednup; 07-07-2014 at 5:28 PM.
Reason: Shameless plug added :)