If done right you can use heat to soften up the corrosion without damaging the beam. I've have done it before and it works. I have never had a faliure due to heating to remove corroded parts. Seems to me it would be better to get it apart and see what you have and arrest the corrosion that's already going on.

I know Dave and I know he hasn't taken the boat completly apart since he bought it and he won't be satisfied until he does.