Every 3 to 4 years. Less frequent if you routinely go up the mast and do a inspection of the goods up there. The other thing beneficial about unstepping the mast, is it allows you to replace halyards, lights, antennas, windex, etc. and lube stuff easily.
We unstepped out mast last year and the year before (had to because of bridge). Probably won't do this haul out, but may in two more years.
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