Originally Posted by boden36
Have not sanded the bottom paint in 25 yrs and have no problems with adhesion.
I guess for a racing
boat is is necessary, but for a cruising yacht with ablative antifoul I reckon it may be more trouble than it's worth.
Same here. I use an industrial scotch bright that is normally used for scuffing car paint for touch up work (and use it wet). Our latest boat had thick paint that needed sanding
along the waterline where extra coats had been added over the years to the point of flaking, so I had to power sand this. I personally prefer 40 grit for this job because it's quick and I reckon the courser the sanding disk, the less fine dust and the less dust problem.
With random orbital sanders, the wattage and no load rpm
are good indications of suitability for task. For wood and paint prep, the higher cost, lower powered units with 10000 rpm
no load speeds are best. For jobs like a/f and sanding fibreglass or fairing materials the high power units with no load speeds of 12000 rpm or greater work the best. I prefer 5" versus the 6"models for the lighter weight and better performance on curved surfaces.