Exterior Hull Stripped and Sanded
With the boat disassembled the next step was to strip paint from the exterior side of the hull. After the exterior of the hull has been completely stripped of paint, I'll be able to easily locate fasteners for removal when replacing the boat's ribs.
No doubt about it, stripping paint is a messy job. You need to protect yourself from older lead-based paints used back in the 60's, from toxin's used in bottom anti-fouling paint, and from fumes of paint stripper chemicals. A respirator is a must as well as protective clothing and gloves to protect your skin from exposure.
Stripping the paint right down to the wood, while it gives you a fresh start is generally not recommended unless absolutely necessary (paint adhesion issues, paint cracks, etc) ... you don't want to sand the wood so much as to reduce its thickness nor remove the outer most plywood veneer... the plywood strakes are only 3/8" thick. Stripping down to bare wood should not be done more than two or three times over the life of the boat. This boat is 55 years old and this is the first time it has been stripped down to the wood. The process has revealed three coats of top paint (all white) and three coats of bottom paint (the original copper-bronze bottom coat, maroon, and red) over a base coat of primer.
There are a number of effective options for stripping marine paint; stripping the paint off with chemical strippers; grinding the paint off with a disk sander; or heating the paint up with a heat gun and scrapping it off with a putting knife is a popular method. Stripping paint with a chemical stripper is messy hard work and your exposed to toxic fumes. Grinding paint is an arduous task as well and you can use up a lot of sandpaper as it is hard to sand marine paint, and you will introduce a lot of paint dust and particles into the air that spread and settle all over the shop... this is especially a concern when grinding toxic bottom, anti-foul, paint. Heating paint up with a heat gun and scrapping it off with a putty knife is very effective but arduous as well... it dries out the wood, and presents a fire hazard as well.
Blasting with soda, a very mild blasting abrasive, is also an option that I considered but I've had no experience with it yet. Consensus seems to be that it is effective but it does mar the wood a bit which can be addressed with some sanding. But again, my concern is that sanding removes material and too much sanding will remove the outer veneer of the plywood.
So, for this task it comes down to a "picking your poison" decision. Having had experience with three methods (except soda blasting), my choice was to use chemical stripper followed by very light sanding.
I've tried a number of different paint stripping products over the years and never have been really being impressed with any one particular product until this project. In stripping the topsides of the boat, I tried various paint stripping products from my local hardware stores, and all required at least three applications.
While stripping the bottom paint I tried a product called Aqua-Strip. It's a non-toxic, bio-degradable formula. It's expensive but had very good reviews. I applied it thick, covered it with Saran Wrap, and let it sit overnight. To my pleasant surprise, I was able to remove all four coats of bottom paint, including a coat of very hard copper bronze anti-foul paint, with just one application, and some aggressive scrapping with a carbide scrapper. This, most definitely, will be my "goto" paint stripper product from now on.
Stripping bottom paint was best done with with the boat flipped upside down.
After completely stripping the boat, I was very pleased with the condition of the wood. There were a few minor issues that will need to be addressed, but all-in-all the wood was in excellent condition for a 55 year old boat (click on an image to zoom it).