Termites in bay boat??? Help!!!!

[Uncle Barty]

I was basiclly given a 1995 ASTRO 21ft center console bay boat due to the fact that the floor underneath the fiberglass was eaten by termites. At first I though this was a B.S. story but the more people I have talked to claim that this is common in older model bay boats. My questions are: How exactly are the termites getting in and is it worth the couple of thousand dollars to get fixed? I got my first estimate...3-6 Thousand...that all depends on the work I do to it before I drop it off and what they find once they rip up the old floor. Note-The boat came with a brand new 80lb thrust trolling motor, Mercury 150 2.0 liter that runs like a champ, new batterys, bimini top, deepth finder, trailer is in good shape, and the overall upholstery is in good shape.