Looking for advice from anyone who has refinished a yak from a traditional varnish to System 3 LPU. I am planning to sand the old varnish off getting the surface back to a matte look. I have never done this before. Anything to look out for, any lessons learned to pass on? What grit is required to cut through 4 coats of 2 year old Captains varnish?

Thanks

Mike