This may not look like much but if you follow my advice it could save you hours. It is in fact abrasive mesh designed for sanding down drywall but I found some years ago that it works a treat for prepping anti fouling ready for re coating.
One of the least popular jobs amongst do it yourself owners is probably painting the bottom of the boat each year. Often working overhead or lying on your back in a cold and windy boatyard the paint drips on everything but before you even get to that unpleasant stage you have to prepare the surface. Anti fouling paint is toxic and dry sanding sends clouds of dust in all directions, coats everything nearby and is a serious health hazard. Wet sanding is safer, produces no dust and with drywall sanding mesh is about 5 times faster than normal abrasives and is a system that I have been personally using for many years.
After power washing the boat and getting off all the big lumps pop down to the local home store and buy yourself a hand drywall sander and some 120 grit sanding mesh. The sander and mesh will cost about $10 in total. Get yourself a bucket of warm water and dip the sander into the water then while still wet start sanding the anti fouling until smooth ready for the new paint. The mesh cuts fast and because it is made from fiberglass with grit impregnated into it, it is water proof and does not clog. The secret is to keep the mesh wet, you will feel as the mesh starts to dry, the sander will drag and slow you down. Run your fingers over the surface to check for smoothness as you go. I have to warn you that the water will run down your arms so now you know why I suggested warm water, it doesn't work any better it is just slightly more comfortable as it dribbles down inside your shirt. You could also use a spray bottle to keep the surface wet as you go but I do feel that you will be pleasantly surprised how fast the jobs goes. The last time I used this sanding method it took me about 2 hours to sand a 30 foot sailboat and I only used two mesh sheets.
I thought I had a picture somewhere of me using the sander but I can't find it right now so by way of a consolation here is a shot of a chap sanding drywall so you get an idea of what a hand sander looks like and what you should be looking for in the DIY shop.
Great tip Mark!! The quicker the better I say....As a DIY boater I do all my boat winterizing and antifouling in the garage and I love anything that will get this job done faster. Love your Blog.. There's nothing as good like it anywhere and I look forward to your daily posts. Keep em coming....so thanks!!
The dust is very toxic and you should do everything to avoid skin contact or breathing it in. Wear a Tyvek suit and a proper respirator at all times.
Works like a charm and no dust. Thank you, great idea!
Hi Mark, just found this article of yours and thought I'd mention I too discovered the joys of using the plaster board sander for antifoul many years ago but I took it one step further. I have attached a small garden watering system tap to the sander, a length of tube and a connector to connect it to a garden hose. By turning on the water at a very low pressure you are able to keep the paddle wet without getting too much over you. First wet the paddle, then turn the tap on the paddle off. Scrub an area till you have a good sludge on the hull. The pressure will build up in your hose and tube, release the pressure to squirt of the sludge and repeat the process. I have been making and selling these simple tools for many years around the place and I'm thinking of extending and broadening the production. Interested?
I just came upon this post and find this method an intriguing alternative to dry sanding. Two aspects of the paint removal process I don't see addressed here, though, are collection and disposal of the sludge. Given the toxicity of bottom paint, they should be part of any removal process - wet or dry. By my calculations, a 32' boat with about 10 seasons of bottom paint build up could produce about a cubic foot of dust if you sand down to the barrier coat, which I plan to do. If I use my sander and vacuum, I know most of it will end up in the bag. But it's noisy and hot process and dust always manages to escapes despite my best efforts at containment. The wet method promises an end to those headaches, but without a means of collecting and disposing of the paint residue, it feels like I'm just trading one set of problems for another. Any guidance those experienced with the wet method can provide regarding collection and disposal would be most appreciated.
The best way to collect the sludge, and the method that I adopt, is to lay a large tarp or sheet of plastic under the boat. To prevent everything running off the edge I use lengths of plastic guttering turned upside down around the perimeter and run the tarp or plastic over the top of that. This forms a sort of mini paddling pool effect and contains the sludge. The sludge can then be sucked up with a wet/dry vac and disposed of in the proper manner.
Good one Mark thanks for the tip.
I am finding it increasingly difficult to get down under my boat so I am going to trial (next Week) using a Uni Pro flexible sanding pole. Also used for finishing plasterboard it should make the lower parts easier to get to as the head that takes the paper swivels around a 180 degree plane. I will try to add a picture if the system allows.
I used the sanding sheets this past week when I had to sand down the bottom of my boat prior to application of another coat of anti-fouling.