Sunday, May 7, 2017

Wet & Wild Sanding

Most antifouling sanding is done with electric or air grinders.  This makes lots of toxic dust which is unhealthy to breathe and also gets deposited and tracked all over our boat and neighboring boats.  It also clogs the sandpaper rapidly.   

I have had good luck in the past with water sanding.  The water washes the paint off the sandpaper and keeps everything cooler so the paint doesn't melt and clump up.  In Mexico, I strapped the hose to the grinder head, made a fiberglass cover for it, and it worked well.  In Australia, Booker sprayed water on the sanding disc while I sanded.  The big problem when using water and an electric sander is the potential of getting shocked.  

Hutchinson Sander
To solve this problem, I bought a Hutchins 7544 Random Orbital Sander.  This is a pneumatic sander with water injection.  Once arranging for the use of an air compressor, we found out that 'Random Orbital" actually means "vibrating".  There is no "orbital" whatsoever.  It just didn't have the guts to sand thick antifouling even with 30 grit sandpaper.  So we need to find a plan "B".

Malaysia is a 240 volt country.  I can't use their electricity to run my power tools.  I have to use the onboard AC inverter.  This makes 110 volts from the boat's batteries and I have discovered that it acts surprisingly like an isolation transformer.  

The best way to explain this is that after doing it's work at the motor, the electricity only has one path to return to the battery, which is through the power cord.  Since there is no path to earth, it can't travel through your body and out your feet giving you a shock.  This is called a Floating Ground.   

***Please do not try this at home or tell my Mom.

Here we are doing the wet sanding.  Booker is doing the spraying and I am doing the sanding.  The green tint is from the sun shade cloth. 

Unfortunately the water sprays everywhere so we are wearing Tyvek suits and hoods.  It is about 100 degrees and we are always trying to work in the shade.

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