Bruce In Bangkok wrote:

Frankly I'm a bit confused with all this talk about people who install
something using 5200 and then have problems taking it out. I wonder
why they use something called an adhesive to install something they
plan to remove. After all, epoxy glue is a pretty fair adhesive but I
don't hear people warning "don't use epoxy, you'll never be able to
take it apart..."

\
Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

And I'm confused too, 5200 is called an adhesive/sealant. I won't argue
that it's a good sealant, but it primarily an adhesive. Sometimes we
make life tougher than it needs to be by using the wrong criteria to
select the material we are going to use.

5200 is a special case. People think that it's stronger and stronger is
always better, when 4200 is a better choice, because you don't need
strength. You need bedding compound. Sealant, not adhesive.

5200 is more of a construction adhesive, like you would use when you
fasten a newly made fiberglass deck to a newly made hull.

I use 4200 on thruhulls because a thruhull does not last forever, you
might want to remove it, I just removed three old ones because of
corrosion, or because you screwed up the threads by cross threading a
new gate valve. A friend of mine just did that by not knowing one had a
tapered thread.

It's a nice sentiment that your thruhull is in place permanently.
Permanent is not always desirable. See the guy with the transducer for
more on that. Or my friend with the screwed up threads, or my old
corroded ones.

When I changed out my old transducer for a new model, and removed the
old corroded thruhulls, I was pleasantly surprised they came out with
minimal effort. I still had to use a 5 pound hammer and a block, and
worked up quite a sweat. Took two days, but I didn't damage the hull
doing it.

It's always a good idea to use appropriate materials in appropriate
applications.