Unstepping ones mast is not something most sailors look forward to so most will avoid doing so for as long as possible. Where boats are stored for the winter unstepping at haul out is a good time to inspect the rigging and make any repairs necessary. I know it is an added expense but at the very least a bi-annual unstepping will save you money in the long run.
Like most cruisers I only unstep when I haul out to paint the bottom, so once every 2-3 years. Though this year we hauled out after 15 months because we experimented with a “enviromentally friendly” bottom paint. It was friendly all right, it let the grass and slime grow as well as a more than a few hard pests. Since I hauled out where it snows and will be covering the boat I unstepped at this haul out. I have a few projects to do to the mast so don’t feel too bad about the process.
That said,this morning at the boat yard we unstepped a mast (not mine, a clients) that hadn’t been out in a long while. As you can see in the photos this mast has lots of corrosion damage that will need to be cut away, in addition the mast step will need replacing as well as modifying to accept the slightly shorter mast, the area around the partners where it goes thru the deck will need work and the spreader tips are heavily corroded.
The end result will be more expensive than the cost of unstepping once every 2 years would have been! Don’t get caught, unstep, inspect and correct any problems found, in the long run it will be cheaper!