Many of the things we do to the boat increase it's static charge. Static is increased by rubbing in one direction, so wiping in one direction with a tack cloth tends to increase the charge, running a vacuum while sanding will also charge it up. Humidity in the air helps to dissipate the charge, so working in nice dry weather doesn't help. There are good reasons for doing these things, but they do tend to make the static problem worse.

Rinsing the boat off with water helps, and a little detergent in the water can also help, but should be thoroughly rinsed off before varnishing. Also wetting down the area to increase the humidity will help disipate the charge. Edgar's idea of an ionizer is a good one as it can reduce the charge difference between the dust and the boat.

: After you've sanded and resanded the epoxy on your boat you've created a
: great big dust magnet. I varnished two boats recently. For some reason the
: static charge was worse than usual. As I wiped down the surface with a wet
: sponge to remove sanding dust the hair on my arm bristled.