There is no more useful tool aboard a steel (or wrought iron) ship than a sandblaster. I found some plans on the internet that gave me some good ideas on how to make my own unit. I found an old acetylene tank in the scrap dumpster in the shipyard and went to work. I filled it with water a few times before I started cutting it apart.
So after cutting off the top and flipping it around and rewelding it to the body, you get this! I added some wheels and a bought some cheap hydraulic hose and the air/water separator and the regulator on Ebay. It uses ceramic nozzles that I bought through the McMaster-Carr website. I run this off the 20hp air compressor already installed on the boat. It is no match to the shipyard sandblaster that can blast a whole boat in one day, but it is perfect for me in that I can run it myself and do lots of small parts.
Here is a detail picture of the filling bowl where the sandblasting grit gets put into the blaster. The threaded rod pulls up a backing plate that has a neoprene gasket on it that makes an airtight seal. As the pressure builds up in the tank, it also pushes the gasket up as well. I have only had to replace the gasket once so far. As the grit can be expensive, I pick up the used grit off the ground in the shipyard and sieve it through a screen to get out the larger bits and then reuse it. I can also sweep up the grit I have already used on the deck and I get about three passes through the blaster with it before it just gets pulverized to dust and doesn’t work very well. A special glass visor helmet/hood, tyvec suit, gloves and a good respirator are all required before starting any blasting.
I turned a metal work table into a temporary blasting booth. It is just a scrappy plywood box with a glass window on top. Its purpose is to contain the grit and dust while working on small parts. I mounted two halogen works lights inside as well as an input to hook up my shop vac. The shop vac isnt pulling out the dust from the box, its actually blowing air into the box on one end, and there is a baffle air vent on the other side, creating a flow of air from one side to the other. It gets very dusty inside when blasting, so the airflow clears the dust enough to see what you are doing. I later installed a pair of heavy rubber gloves there the two arm holes are here. I nailed old firehose over all the moving seams of the box, to make it as airtight as possible. Underneath the grating seen here, there is a screen that allows me to filter the used grit and gravity feed it into a bucket for reuse. Here are some turnbuckles and parts freshly de-rusted.
Once I had the power to sandblast, I didn’t want to stop! Anything that would fit in the blast cabinet was fair game! And then I got really ambitious and started blasting the inside of the gunwhales and the main deck. It took awhile, but it was progress every day. After blasting to bare metal – I primed everything with the green Dimetcoat inorganic zinc primer. Some real progress!