What is the best or easiest way to remove old bottom paint?
Dan Dickison responds:
What you're facing here is a series of decisions. There are often environmental restrictions regarding the removal of bottom paint, in fact, these are in place in most states in the US, and Canada I believe. Youll need to be aware of these before starting the job. Also, some boatyards won't let you do this yourself, while others require that you tent your boat and put down a collection drop cloth before you start the job to protect surrounding boats and areas from resulting dust and detritus.
Once you've attended to those details, you need to consider the surface from which you are taking off the paint. If it's wood, aluminum, or steel, you can probably grind off the paint with a grinder and a fine-grit pad. You can also have it sand-blasted off or wet-blasted off with a combination of sand and water. Some firms are even offering a new method that uses a jetted spray of baking soda and water with good results. If the surface is gelcoat over fiberglass, you should probably keep the grinder away and use a solvents or light sanding action.
If you've got an older boat, it's likely that you'll encounter a buildup resulting from several layers of bottom paint, so you'll need lots of rags if you're using a solvent. Be sure you have a safe, legal place to dispose of those rags after you've finished with them.
And don't short yourself on protective gear. Remember, bottom paints are intended to ward off marine growth, meaning they're not really healthy for anything that lives. So get a good set (or several sets) of rubber gloves, a respirator (or at least some quality dust masks) and some shop goggles so that you cover yourself completely. It's also a good idea to have this gear on hand when you're applying the new pain.
I hope this information helps you. If you're still daunted or uncertain, you might try getting some advice in person from the folks at a local boatyard.