On Jan 31, 7:51 pm, "Jay Chan" wrote:
...snip

It is 18-ft with 7-ft beam, and it is a very typical center console. It has a 115hp outboard.
The whole hull is fiberglass with wood structural members. The bottom
of the hull is solid fiberglass.
I have a page of the boat in my web site he http://www.geocities.com/jaykchan/index.htm

**T* Jay, could you email me a photo at ??
Sigh..
- You are on GeoCities
- One or more of the 1000's on Geocity said something about the
president of the Country I am in.
- Geocities.com is "Impossible de trouver la page" in this country


The existing floor is seamlessly connected to the side of the
gunwhale, and the floor is supported by wood stringers.

The floor is not anchored permanently on the wood stringers.

The center console is resting directly on the wood stringers, and is
not connected to the floor. I am not quite sure how the center
console is being attached to the wood stringers though.
....
**J**
The gunwale is hollow. The inner side of the gunwale connects to the
floor, and the outer side connecting to the side of the hull. I have
a feeling that the hull is made in one piece from one mold, and the
gunwale/floor combo is made in one piece from another mold.
And then they are attached together like this (please use fixed-spacing font
like Courier to view the line art):

Gunwale/floor combo:

/----\ /----\
| | | |
| |
| |
|----------------------------|

|
| Attached to
V
Hull:

| |
| |
\ /
\ /
\ /
\--------\ /--------/
\ /
\--------/

**T* OK, that's what I thought. Yes, this boat is made by making the
hull in one mold, adding some wood/glass supports to the hull, and
making the top/gunwhale/inside-sides/floor in another mold, and mating
the two pieces together.

** Why are you using 3 layers of plywood? If you do, how will they be attached to each other?

**J**
I get that idea by reading the guy in www.continuouswave.com who
replaced his rotten deck with 3 layers of 1/4" plywood all glued
together using thickened epoxy. His idea of using 3 thin layers
instead of 2 thicker layers is to be able to stack the joint. I guess
if I can find one large piece of marine plywood, I will be able to use
one thick layer instead of 3 thin layers. But I have a feeling that I
may have a problem locating one large piece of marine plywood. The
mail order houses seem to only ship in small pieces. I guess this is
about time for me to look for a mail order house that can ship one
large piece of plywood.
,,snip..

**T* OK, that's a method of making 'long' plywood.. But, since you
don't NEED
long plywood, and the 'floor' is not hull-structural, there are other
possibilities..

**T* Blasphemous-according-to-some idea: I have used higher-grade
Pressure-Treated plywood for some boat sections. I scrubbed it down
hard with detergent, dried it inside, then supported it in the sun for
a few days before (carefully with mask) cutting / epoxying it. The
off-boat samples I did seem to have fine adhesion..
If I had to replace that floor right now, I'd use pressure-treated 1/2
- 5/8 or 3/4 plywood (depending on the span and springiness you can
accept.). Adding 3 layers of glass on top (to survive another 20
years of foot traffic) and one or two on the bottom will make it a lot
stiffer. I bet 1/2" with all that glass would be fine. Consider
using a colorant in the last 2 top layers, and never paint it!

Major part of the work is to assess and repair and add the floor
stringers so that the floor both has adequate support AND has good
places for the floor joints. Since the floor is not structural and
will not have any tension loading you don't need much in the way of
attachment except you don't want it moving / vibrating underway.
Stainless steel screws are OK as long as you do NOT paint them in
place or bury them in glass. Turns out Stainless needs Oxygen to keep
it's corrosion resistance! I'd use countersunk (epoxy over the raw
edge) holes and those square-drive BeaverBite screws, myself. Then the
floor sections are removeable. I'd want to remove them every year or
two to clean everything and check the stringers etc.

AND the stringers! Better get a good look at them and see if any have
gotten wet or got any rot.

Look at:
Epoxy Knowhow and
Chemotherapy for Rot
at: http://www.angelfire.com/nc3/davecarnell/
(Hopefully your local government hasn't Fired the Angels)

Second Point of Blasphemy: I have a few wood areas in my current boat
(28 years) that have some rot, but are pretty sound still, and are
mostly encapsulated in Glass. Now they have several 1/4" holes it the
topmost point and get a yearly dose of DaveC. Stable, no changes, no
evidence of any biological activity, after 5 to 8 years of this. And
a LOT less toxic than the PentaChlor I used to get at the Marina. Yup,
PCP! No longer available.. The "Penetrating Epoxy" I used earlier
on rot worked. Until it rotted all AROUND it! :-(

I think you can handle this well, once you get into it... I agree you
should pull the console, mainly to get a look at its stringers.

Your idea of using bracing strips is good. Actually the rear deck
area of the boat is totally under-braced and I should add additional
bracing in there anyway. Let me ask you a quesion: Let say we have
added additional bracing to make sure the bracing strips are not more
than 2-ft apart, and we use 3/4" marine plywood (in one piece or in 3
thin layers combined).
**T* Stringers: Mahogany is great stuff, but getting hard to find and
expensive. I used Cedar Flooring on edge for some floor stringers and
cabin roof stringers. And the epoxy-on-cedar looks real nice in the
cabin...

How many layers of fiberglass would you recommend?

I know that you will recommend using 2 layers of fiberglass if I use
1/2" marine plywood instead of 3/4" because you have mentioned this
below.

**T* Sounds good. You COULD test a floor section after N layers of
glass to see how stiff it was...
...snip

**J**
Great to know this! This means 1/2" or 5/8" plywood is a viable
alternative to 3/4" thick plywood. Good, less thick means lower
weight. And I will use 2 layers of fiberglass/epoxy -- may be 3 (just
to be in the safe side)...

** I think I would consider making the "deck" removeable for sure.


**J**
I have the same feeling too. I will be making the floor in multiple
small sections instead of one giant piece. A small piece is easier to
handle than a giant piece anyway.

**T* Hope someone else will comment; I know some of you guys have done
a lot; I have only done what I've done, on 2 boats.... Terry


Jay Chan