James is right. Epoxy is more flexible, water-proof (as he says, poly
resin is NOT) and stronger by weight.

I wouldn't be so quick to assume the stringers are only there to
support the deck. When I removed my stringers (yes it was quite a job,
but well worth it) they were essentially mush, so they provided little
support as is. When I replaced them (as I think I said I sealed
[soaked] them with thin epoxy first) and 'glassed' them in with
fiberglass roving I could tell the whole boat was a LOT stiffer,
completely different. I am a big guy and when I walked around inside
the hull, I could feel it flex, so I put boards (planks) down I could
walk on so I didn't maybe go through a thin spot on the hull bottom.
After putting in the stringers (no deck yet,) it just felt a whole lot
different.

I used USComposites Epoxy and was VERY pleased with it. I found it to
be the least expensive. I bought both Thin and Thick (thin for sealing
wood and thick for fiberglass layup) epoxy. I also bought high-density
flotation 'expanding foam' (comes in two-part liquid form) to pour
in-between the stringers. The Coast guard requires a specific amount of
flotation in boats so I did the math and poured the correct amount in.
Again, it worked great.

After putting the deck on (I epoxied the entire deck on ALL sides first
- two coats, sanded between coats) then the boat felt even stiffer. I
can tell you FOR SURE that the boat performs a lot better than it ever
did in rough water. It's a modified tri-hull and the rigidity seems to
allow the boat to keep going over the waves instead of soaking up the
impact and slowing. It's difficult to describe, but it's a noticeable
difference like putting more air in an inflatable boat.

I hinted about this in my last post, but BE SURE to calculate where the
seats and any other stress points will be in the boat BEFORE you put
the deck on. You can build this into the stringers/cross braces so
stress is transferred properly across the bottom of the boat. Also,
epoxy or glue and screw your deck down to the tops of the stringers. I
pre-drilled all the holes for the screws and dropped a little epoxy in
each hole before screwing the screw in. I don't want to give the water
ANY place to enter the stringers again.

Also keep in mind that you can put epoxy over properly prepared
polyester resin, but you CANNOT put poly resin over epoxy. Well you
can, but it won't stick very well and it will eventually fail, so don't
waste your time. It easier and better to only use epoxy.

I am considering building a little website covering the whole process I
went through with photos, etc. I sure wish I could've known everything
I know now before I started.

Jeff





anxious boater wrote:
Hi Jeff,

You sometimes don't know what you're getting into. Some advice I read and
didn't head - "If you find yourself in a hole, STOP DIGGING!"

Because of the stringers I also ended up pretty much gutting the boat. At
least I can now build something I'll be happy with.

A surveyor I talked to suggested that I epoxy the entire hull while I was
doing everything else. You did that. I never asked him why I should. Why did
you go that route?

"Chehalis Jeff" wrote in message
oups.com...
Hi Steve,

I have a 1972 boat that had the same problem I spent the greater part
of last summer fixing. I read everything I could find to read about it
and then decided to do the job myself. It turned out great and I think
the boat is stronger and lighter than original.

I agreed to paint my dad's house (a bigger job than anticipated) in
exchange for the "family boat" that dad no longer used (but it was
stored in 'dry' storage.) After making my dad's house beautiful, I went
to load up the boat and stepping onto the deck I went right through. It
was rotted through and through. I then realized the deal I made with
dad wasn't such a great deal- well maybe for my dad it was, and that's
OK I guess.

Anyway I brought the boat home and went about stripping the boat down
(removing all interior upholstery and hardware) removing the deck and
stringers. I cut everything down to the bare hull and made sure to kill
any sign of mildew or mold (didn't want it growing under anything...)
Fortunately for me, the transom was OK - there were a couple of tiny
rot spots in it I was able to repair.

Now that I had a completely clean hull, I laid out stringers out of
Alaska Yellow Cedar (not for strength, but because it doesn't rot)
fitting them closely to the hull line. I made up cross-braces out of
marine-grade plywood. Before placing ANY wood in the boat, I first
coated it in thin epoxy that soaked into the wood (sometimes two coats
if it looked like it needed it) which didn't increase the weight of the
wood by much. This way I knew the wood was totally encapsulated. Then I
placed the wood into the boat, laid everything out and screwed/glued
the cross braces to the main stringers with cleats (also pre-treated.)
I also added supports for the deck (places to attach the deck and seats
down to the stringers/cross-braces.)

Once everything was in place I started lay up. I used a coarse
fiberglass mat (I used as large pieces of fiberglass mat as possible -
eliminating as many joints and overlaps as possible) for the first
layer. I did NOT use polyester resin, instead I used epoxy for the
entire job. This takes a little longer since I think it's important to
allow the epoxy to cure between coats which can take a week. After my
first layup, then I used a finer cloth over the heavy cloth, making
sure the joints and overlaps in this cloth were in different places
than the first layup. Again, I used epoxy and at this time I also
coated the entire inside of the hull. (One thing to make sure of before
you start this is to support the boat hull in such a way so that it's
not deformed [even a little] because however the hull is shaped when
you start, is how it will be shaped forever.)

After a lot of work and a couple gallons of epoxy, it came out
beautifully and the boat actually works better than ever. I think it's
a little stiffer and it definitely feels more solid
than before (that is, before it rotted out.) From what I removed from
the boat I could tell it was not put together very well... there was no
glass mat, only chopper material covering the stringers which is why I
think it failed. The thickness of the chopped glass varied a lot.

That's my story...


Jeff





anxious boater wrote:
I have a 1969 fiberglass (polyester) hulled houseboat. It's a Thunderbird
Drift-R-Cruise. All the engine stringers and three interior stringers are
shot. Everything I have read so far basically says to epoxy the stringers
in,
fillet and glass over. I am certain the first two steps were omitted,
either
when this boat was built or this job was done in the past. Some of the
inside stringers aren't even resting on the hull interior surface. From
what
I can see, water leaked in at the bow (and other places) and simply
migrated
to the back of the boat. The rot is really bad starting in the bilge (the
stringers oozed out when I started cutting!) and improves some moving up
closer to the bow. Is this poor boat building, or just the way it was
done
back then?

Now I'm not so sure that I should put the new stringers in using the
current
methods. For example, will the vibration from the motors cause cracking
in
the hull glass if they are epoxied in, solid as a rock?

Thanks,
Steve