Ofcaurse it can , it's been done over and over again but as you expect
not allway's as good as it can be done and nothing last forever.
Still there are a lot of misunderstandings ,the vorse are the to
obvious that only a layer is used or that that layer just cover what is
under water.
The rule is that if done as a quality work the new hull build up
outside the old must be stronger than the original. Also it is allway's
best when the glasfiber cover all way round and not just the hull.
Rot ask oxygen and by covering you make sure no oxygen can feed the rot
,still that don't mean that the wood can't be soaking wet and this
often surprise amatures but wet wood are soft. it is not off topic to
look at the wooden boats where concrete been poured as ballast inside
the hull and strait on the planking ---- you never see rot there so why
shuld you see rot under glasfiber it's an old misunderstanding remember
rot ask oxygen --- Anyway that rot we talk about the one that harm the
wood.
Acturly sometimes it can be a problem that if it is a real old boat,
that the wood will dry out when glasfibered, --- well if the job is
done proberly that is. But any geat idea can be ruined by greed, you
will se plenty bad jobs ,where the only right thing to do is to tear
off the glasfiber and start all over and do it right. Now that to is
the only right way to make the repairs ,find the lose places and redo
the glasfiber.