I not sure of the purpose. Is it for below or above the waterline or both?
I know that boatyards
use pressure washers that are way more that 2000 PSI. So the possibility exists that yours may not be adequate for blasting away the critters. You absolutely want to keep it away from any type of wood. As far as blasting what type of non-skid? Gelcoat
non-skid? That should not be a problem. Painted on non-skid...that depends on the type of paint that was used. If it was Awlgrip then it should be no problem but if it was plain old boat enamel that may be a problem. I would do a few test patches first.
I took a pressure washer to my whole bilge
once. I had a great time blasting away the years of accumulated crud.