Glass hulls can last a long long time - and be very fix uppable.

I assume you are talking about "true" fiberglass boats that don't use
foam or balsa wood as core material of the hull. I am glad to hear
this. Thanks.

The problem is how I can tell if a gel-coated boat is really a "true"
fiberglass boat? According to Yacht Survey Online, there are many
gel-coated boats that have very little fiberglass on it. I am hoping
that someone can tell me something like:

"Model year 1976 to 1985 of SuperFisher-XL
from company-XYZ were all true fiberglass
boat; unfortunately, all their recent boats
from 1986 and on only have a thin layer of
fiberglass in the interior side of the hull"

or something like that. Then I can use it as a guide to quickly narrow
down the selections.

But exposed wood in them is a disaster - if it is structural - better
to avoid them and leave the rot to other people.

I am wondering whether I can remove the rotted wood and use it as a
template to make a replacement. In TV show "ShipShape IV", the host of
the show removed the entire rotten wooden transom and fabricated a new
one with wood and epoxy / fiberglass.

I guess this depends on how much the hull costs. If the hull has rotten
wooden structural elements, and they still ask for a thousand dollar
for the hull, I will definitely take your advice and walk. On the other
hand, if they are only asking for a couple hundred dollars, I may still
consider.

Obviously, this is even better if the hull doesn't have that kind of
structural problem even if the hull costs a bit more. Therefore, I need
to go around and shop often to find a good deal.

The things that I really want to know are those problems that cannot be
fixed, or cannot be fixed economically (as comparing to the
alternative), or require skill that an average person doesn't have even
if he is willing to follow instruction.

Let's say the hull has a 5" crack on one flat side. I "assume" that
this can be fixed by applying a couple layers of fiberglass in both
sides of the cracked area. I am just guessing here.

On the other hand, if the bow of a boat has rammed into something and
the bow has cracked open and one side of the bow seems to be deformed.
I "assume" this is not something that we can fix because the complex
angle in the bow area and this is probably tough to force the deformed
area back into the right shape. Again, I am just guessing here.

I have a feeling that this is an open-ended question. I may be better
off getting a book about doing major repair on boat hull, learning the
techniques, and trying to figure out if I can apply the techniques to
fix a boat that I will be looking at.

Thanks for the info though.

Jay Chan