the raging debate of marine plywood / fiberglassing / etc

kyle wrote:
> hi all,
>
> i've been searching through the group .. i keep finding conflicting
> opinions.. hoping i can ask my exact question and get an answer
>
> i just bought a 2003 bayliner 2150 classic (21.5 foot ski boat
> basically). the previous owner left the boat out in the sun/water/etc
> for 3 years without a cover!! the carpet is trashed. i ripped it all
> up tonight. low and behold, the plywood is rotten.
>
> question1) how do i remove the rotten plywood.. do i take a saw and
> just cut the wood out.. or is it screwed in somewhere.. do i need to be
> careful *where* i cut? what is underneath the plywood.. more wood
> (that is probably rotten as well)??
>
> question2) i've read that if you fiberglass over plywood, sometimes the
> fiberglass cracks and lets water seep into the plywood and rots all
> over again.. ?? myth or truth?
>
> question3) so.. what i really want to do is have plywood and then a
> paint with sand in it to give a grip to the feet when walking.. and be
> done with it.. what plywood/paint/anything in between the two should i
> use?
>
>
> many thanks!!!

You need to remove the rotted plywood. If it's rotted any screws
shouldn't be that much of a problem, the screws should pull right
through. I suspect underneath you'll find the bilge (obviously) and
flotation material that is probably waterlogged as well, it will need
to be replaced as well. Fiberglass, properly applied to plywood, should
last a long time. Avoid very thin wood as it may flex too much, causing
the fiberglass to crack allowing water to get in. Try a local marine
shop for paint and the sand additive, but outdoor carpet is usually
easier, cheaper and looks better. I have seen people coat the floor
with gell coat that has been thickened and applied with a roller to
give a rough finish, too rough it'll take the skin off your bare feet,
so most sand it down some, but this finish looks pretty good.

John
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

thanks so much for responses.

i am going to take a chunk of rotten plywood out tonight and see if the
stringers are rotten. if they are, i don't know what to do.. pay $1K
for a professional? i am no match for replacing stringers.. i'm a
newbie..

if stringers are okay.. then i will get marine plywood, roller two
coats of epoxy on both sides and if any wood needs jointing, do butt
joints, sand to 80grit, then apply Skid-no-more to the top surface, and
be good as new.

does this sound like an okay plan? i want to do away with carpet
because of the rot factor..


Capt John wrote:
> kyle wrote:
> > hi all,
> >
> > i've been searching through the group .. i keep finding conflicting
> > opinions.. hoping i can ask my exact question and get an answer
> >
> > i just bought a 2003 bayliner 2150 classic (21.5 foot ski boat
> > basically). the previous owner left the boat out in the sun/water/etc
> > for 3 years without a cover!! the carpet is trashed. i ripped it all
> > up tonight. low and behold, the plywood is rotten.
> >
> > question1) how do i remove the rotten plywood.. do i take a saw and
> > just cut the wood out.. or is it screwed in somewhere.. do i need to be
> > careful *where* i cut? what is underneath the plywood.. more wood
> > (that is probably rotten as well)??
> >
> > question2) i've read that if you fiberglass over plywood, sometimes the
> > fiberglass cracks and lets water seep into the plywood and rots all
> > over again.. ?? myth or truth?
> >
> > question3) so.. what i really want to do is have plywood and then a
> > paint with sand in it to give a grip to the feet when walking.. and be
> > done with it.. what plywood/paint/anything in between the two should i
> > use?
> >
> >
> > many thanks!!!
>
> You need to remove the rotted plywood. If it's rotted any screws
> shouldn't be that much of a problem, the screws should pull right
> through. I suspect underneath you'll find the bilge (obviously) and
> flotation material that is probably waterlogged as well, it will need
> to be replaced as well. Fiberglass, properly applied to plywood, should
> last a long time. Avoid very thin wood as it may flex too much, causing
> the fiberglass to crack allowing water to get in. Try a local marine
> shop for paint and the sand additive, but outdoor carpet is usually
> easier, cheaper and looks better. I have seen people coat the floor
> with gell coat that has been thickened and applied with a roller to
> give a rough finish, too rough it'll take the skin off your bare feet,
> so most sand it down some, but this finish looks pretty good.
>
> John
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

Lew,

Thanks for the response. Two questions.

1) 4" "boat tape" (about 6 OZ glass) -- is this 6 OZ fiberglass, or is
it something else called "boat tape" (or they are one in the same)??

2) If I fiberglass, then lay marine carpet.. what do you think the life
expectancy of the deck will be with continuous water splashing on the
deck soaking into the carpet?? or should i just do the evercoat
skid-no-more solution.. this is my first boat and i am worried it might
hurt the kids feet? but i don't want to do this whole project over 3
yrs from now either...



Lew Hodgett wrote:
> kyle wrote:
>
> <snip>
>
> > question1) how do i remove the rotten plywood.. do i take a saw and
> > just cut the wood out.. or is it screwed in somewhere.. do i need to be
> > careful *where* i cut? what is underneath the plywood.. more wood
> > (that is probably rotten as well)??
>
> Remove the plywood in as large a piece(s) as possible, then later use
> them as a pattern for replacement.
>
> > question2) i've read that if you fiberglass over plywood, sometimes the
> > fiberglass cracks and lets water seep into the plywood and rots all
> > over again.. ?? myth or truth?
>
> It depends.
>
> Epoxy provides a water tight bond to wood, polyester resin does not.
>
> Use epoxy for repair work.
>
> > question3) so.. what i really want to do is have plywood and then a
> > paint with sand in it to give a grip to the feet when walking.. and be
> > done with it.. what plywood/paint/anything in between the two should i
> > use?
>
> You can use any kind of plywood available if you cover it with epoxy
> and glass.
>
>
> If it were me, I'd use a piece of cheap, 1/2", 4 ply, CDX plywood with
> a layer of DB170 (17 OZ, double bias, knitted glass) on each side,
> then seal the edges with a layer of 4" "boat tape" (about 6 OZ glass).
>
> It will be bullet proof.
>
> Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

OK. Awesome answers. One more question then I'm done for the day

When I cut the piece of rotten plywood out from th eboat, then cut a
fresh piece in the exact size.. what do I do first?

1) I fiberglass/epoxy it the 4 coats (seal, bond, fill, finish -- are
all of these needed for what i'm doing??) -- both sides & edges
2) do I need to create any butt-joints to mesh with other sides of
plywood still mounted to stringers?
3) apply a thick coat of sikaflex to the stringer, then lay the glassed
piece down / joint it

?


Lew Hodgett wrote:
> kyle wrote:
>
>
> > 1) 4" "boat tape" (about 6 OZ glass) -- is this 6 OZ fiberglass, or is
> > it something else called "boat tape" (or they are one in the same)??
>
> They are one and the same. "Boat Tape" is a generic description of a
> light weight glass tape sold in 50' rolls.
>
> > 2) If I fiberglass, then lay marine carpet.. what do you think the life
> > expectancy of the deck will be with continuous water splashing on the
> > deck soaking into the carpet?? or should i just do the evercoat
> > skid-no-more solution.. this is my first boat and i am worried it might
> > hurt the kids feet? but i don't want to do this whole project over 3
> > yrs from now either...
>
> Save your money and forget the carpet.
>
> The glass itself will provide a rough enough surface, just paint it to
> provide UV resistance for the epoxy.
>
> BTW, you want to bond the new deck to the stringers with SikaFlex 291.
>
> Have fun.
>
> Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

kyle wrote:

<snip>

> question1) how do i remove the rotten plywood.. do i take a saw and
> just cut the wood out.. or is it screwed in somewhere.. do i need to be
> careful *where* i cut? what is underneath the plywood.. more wood
> (that is probably rotten as well)??

Remove the plywood in as large a piece(s) as possible, then later use
them as a pattern for replacement.

> question2) i've read that if you fiberglass over plywood, sometimes the
> fiberglass cracks and lets water seep into the plywood and rots all
> over again.. ?? myth or truth?

It depends.

Epoxy provides a water tight bond to wood, polyester resin does not.

Use epoxy for repair work.

> question3) so.. what i really want to do is have plywood and then a
> paint with sand in it to give a grip to the feet when walking.. and be
> done with it.. what plywood/paint/anything in between the two should i
> use?

You can use any kind of plywood available if you cover it with epoxy
and glass.


If it were me, I'd use a piece of cheap, 1/2", 4 ply, CDX plywood with
a layer of DB170 (17 OZ, double bias, knitted glass) on each side,
then seal the edges with a layer of 4" "boat tape" (about 6 OZ glass).

It will be bullet proof.

Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

kyle wrote:


> 1) 4" "boat tape" (about 6 OZ glass) -- is this 6 OZ fiberglass, or is
> it something else called "boat tape" (or they are one in the same)??

They are one and the same. "Boat Tape" is a generic description of a
light weight glass tape sold in 50' rolls.

> 2) If I fiberglass, then lay marine carpet.. what do you think the life
> expectancy of the deck will be with continuous water splashing on the
> deck soaking into the carpet?? or should i just do the evercoat
> skid-no-more solution.. this is my first boat and i am worried it might
> hurt the kids feet? but i don't want to do this whole project over 3
> yrs from now either...

Save your money and forget the carpet.

The glass itself will provide a rough enough surface, just paint it to
provide UV resistance for the epoxy.

BTW, you want to bond the new deck to the stringers with SikaFlex 291.

Have fun.

Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

kyle wrote:

> When I cut the piece of rotten plywood out from th eboat, then cut a
> fresh piece in the exact size.. what do I do first?
>
> 1) I fiberglass/epoxy it the 4 coats (seal, bond, fill, finish -- are
> all of these needed for what i'm doing??) -- both sides & edges
> 2) do I need to create any butt-joints to mesh with other sides of
> plywood still mounted to stringers?
> 3) apply a thick coat of sikaflex to the stringer, then lay the glassed
> piece down / joint it


My answers are based on replacing the entire sole, not just part of it.

You fit the plywood, then glass it totally to encapsulate it, then
finally fit it using the SikaFlex 291.

Finally, you come back and seal the sole to hull joint with a layer of
boat tape.

If you have butt joints in the plywood, seal them with a layer of
DB-170, say 8" wide, on both sides, then come back and finish glassing
the plywood.

The alternate is to use 2 layers of plywood, say 3/8" thick, spacing
the butt joints so they are covered.

Have fun.

Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

I know it's a little off from what I had mentioned earlier.. but I was
talking with my brother about my plan.. and he said you really should
put carpet down on a ski boat.. well with that in mind...

Could I simply spread 2-3 coats of epoxy (no fiberglass) and then put
the marine carpet down?

Or should I do the full nine yards of 4 coats of epoxy/glass and then
lay the marine carpet over that? What is the fiberglassing buying me?



Lew Hodgett wrote:
> kyle wrote:
>
> > When I cut the piece of rotten plywood out from th eboat, then cut a
> > fresh piece in the exact size.. what do I do first?
> >
> > 1) I fiberglass/epoxy it the 4 coats (seal, bond, fill, finish -- are
> > all of these needed for what i'm doing??) -- both sides & edges
> > 2) do I need to create any butt-joints to mesh with other sides of
> > plywood still mounted to stringers?
> > 3) apply a thick coat of sikaflex to the stringer, then lay the glassed
> > piece down / joint it
>
>
> My answers are based on replacing the entire sole, not just part of it.
>
> You fit the plywood, then glass it totally to encapsulate it, then
> finally fit it using the SikaFlex 291.
>
> Finally, you come back and seal the sole to hull joint with a layer of
> boat tape.
>
> If you have butt joints in the plywood, seal them with a layer of
> DB-170, say 8" wide, on both sides, then come back and finish glassing
> the plywood.
>
> The alternate is to use 2 layers of plywood, say 3/8" thick, spacing
> the butt joints so they are covered.
>
> Have fun.
>
> Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

kyle wrote:
> I know it's a little off from what I had mentioned earlier.. but I was
> talking with my brother about my plan.. and he said you really should
> put carpet down on a ski boat..

<snip>

Do as you choose, but IMHO, carpet belongs in houses, not on boats.

Can't think of a single reason to put carpet on a boat, but everybody
has gotta be someplace.

Lew
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

kyle wrote:
> hi all,
>
> i've been searching through the group .. i keep finding conflicting
> opinions.. hoping i can ask my exact question and get an answer
>

Stitch and glue driftboats are a special case, that make
a good general point, I think.

A driftboat (a dory that drifts down a river) gets its
bottom pounded like no other boat. No matter how
much glass you put over the bottom and chine, cuts
in the glass skin will inevitably expose the plywood.
Then the plywood wicks up moisture, which gets trapped
almost forever, between the glass skins.

Some guys (montana boat builders dot com) have essentially
solved that problem (for stitch and glue boats anyway) by
puting hot spray truck bed liner on the outside.

Another way to deal with it is to use plastic honeycomb core
for the bottom panel, instead of plywood. If you do that, you
need a little extra glass, to stiffen the panel sufficiently.
But when and if the skin gets cut, the moisture does not
wick sideways into the honeycomb.

For me it's all about do-it-yourself boatbuilding, not
necessarily with wood. Plywood makes good side panels
on dories.......a place that doesn't get pounded.
For bottom panels on driftboats, I don't like plywood.

Plascore (or nida core) might be a better core for
any homemade boat.
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

On 15 Oct 2006 08:23:29 -0700, "Leaks" <Sandy.Pittendrigh DeleteThis @gmail.com>
wrote:

>
>kyle wrote:
>> hi all,
>>
>> i've been searching through the group .. i keep finding conflicting
>> opinions.. hoping i can ask my exact question and get an answer
>>
>
>Stitch and glue driftboats are a special case, that make
>a good general point, I think.
>
>A driftboat (a dory that drifts down a river) gets its
>bottom pounded like no other boat. No matter how
>much glass you put over the bottom and chine, cuts
>in the glass skin will inevitably expose the plywood.
>Then the plywood wicks up moisture, which gets trapped
>almost forever, between the glass skins.
>
>Some guys (montana boat builders dot com) have essentially
>solved that problem (for stitch and glue boats anyway) by
>puting hot spray truck bed liner on the outside.
>
>Another way to deal with it is to use plastic honeycomb core
>for the bottom panel, instead of plywood. If you do that, you
>need a little extra glass, to stiffen the panel sufficiently.
>But when and if the skin gets cut, the moisture does not
>wick sideways into the honeycomb.
....


Which reminds me - a Lake patrol man showed me the bottom of his
airboat one day. To allow it to dock right up the ramp onto the hard,
they fitted the bottom with a low friction plate - either high density
polyethylene - or it might even have been teflon.

Brian Whatcott Altus OK
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc 

kyle writes:

> what i really want to do is have plywood and then a
> paint with sand in it to give a grip to the feet when walking.

Don't use sand (silica). It will be coming loose continuously and ruining
all sorts of mechanical things and surfaces due to its hardness.

Use pumice grit. Provides a tread, but doesn't spoil mechanisms if it gets
into a machine.
 >> Stay informed about: the raging debate of marine plywood / fiberglassing / etc