Re: Substituting plywood for lumber
Another option is whatever they call it with fiberglass where the
thing goes around in channel form. You have the hull side, it goes
inboard an inch or two, then down an inch or two. If all glassed, it
would look good, and be very strong.
thing goes around in channel form. You have the hull side, it goes
inboard an inch or two, then down an inch or two. If all glassed, it
would look good, and be very strong.
> Choose the best of it and scarf it for lenght or laminate for
> thicker pieces Seems easy to me. laminating srips of ply would use
> lots of glue and being narrow not give alot of strenght I reckon.
>
> Paul
--- In bolger@y..., "rdchamberland" <cha62759@t...> wrote:
thicker pieces Seems easy to me. laminating srips of ply would use
lots of glue and being narrow not give alot of strenght I reckon.
Paul
> Thai Sean raises an interesting question on the instant boatlumber
> website www.instantboats.com
>
> Best read the original yourselves however in a nutshell he has
> returned to southeast asia and wants to build a boat. Straight
> is not available to him. Whatever lumber he could find would have toof
> be hand planed to get the crooks out etc.
>
> He asks about the feasibility of building his boat almost entirely
> plywood.Choose the best of it and scarf it for lenght or laminate for
> Bob Chamberland
thicker pieces Seems easy to me. laminating srips of ply would use
lots of glue and being narrow not give alot of strenght I reckon.
Paul
Right. Foam panels are also used as stringer cores in powerboats
(I'm assuming you are referring to boats made primarily out of
fiberglass.) Foam cores have no grain. Their strength - if any - is
unidirectional. The real strength in that scenario comes from
creating a fiberglass box section with the foam (or plywood)
stiffening it and preventing it from collapsing. A majical
combination, as pointed out by a member in a recent post.
Plywood has more stiffness in the primary grain direction because
most of the plys run that way. But it is not as stiff as solid
lumber because not ALL of the plys run that way. This is an
advantage in some situations, but a downfall in others. Like the
thwart example, for instance. Plywood would not do near as good a
job of spanning the gap between frames as solid lumber.
I think we are all on the same page here - plywood is great stuff
when used properly. Lumber has the advantage when you need strength
concentrated in one direction, or nail and screw holding ability
(depending on which direction the fasteners are coming from), or (I
think) weathering ability when finished bright.
This is a fun group! I'm enjoying the interchange of ideas very much.
gbb
(I'm assuming you are referring to boats made primarily out of
fiberglass.) Foam cores have no grain. Their strength - if any - is
unidirectional. The real strength in that scenario comes from
creating a fiberglass box section with the foam (or plywood)
stiffening it and preventing it from collapsing. A majical
combination, as pointed out by a member in a recent post.
Plywood has more stiffness in the primary grain direction because
most of the plys run that way. But it is not as stiff as solid
lumber because not ALL of the plys run that way. This is an
advantage in some situations, but a downfall in others. Like the
thwart example, for instance. Plywood would not do near as good a
job of spanning the gap between frames as solid lumber.
I think we are all on the same page here - plywood is great stuff
when used properly. Lumber has the advantage when you need strength
concentrated in one direction, or nail and screw holding ability
(depending on which direction the fasteners are coming from), or (I
think) weathering ability when finished bright.
This is a fun group! I'm enjoying the interchange of ideas very much.
gbb
--- In bolger@y..., "proaconstrictor" <proaconstrictor@y...> wrote:
> Good points.
>
> Plywood is used extensively for stringers in the powerboat world,
all
> they do is fit them as hollow box beams, and glass over them. this
> would be easy to do on a small boat, either as a variation on a
deck,
> or as a means of caping something like blue foam. There would be a
> certain amount of wast, since you would need to cut the curves, but
> if you scarphed it, it wouldn't be all that bad.
>
>
>
> -- In bolger@y..., "gbb132000" <gbb132000@y...> wrote:
> > It depends on the application. You have to remember that
> alternating
> > the grain direction in plywood has up sides and down sides.
> >
> > For instance, if you layered strips of plywood to the same
> dimensions
> > as a 2 x 12 joist, it would not be near as strong as an actual 2
x
> > 12, because 1/2 to 1/3 of the wood would have the grain running
the
> > wrong way.
> >
> > When you see engineered lumber, what LOOKS like plywood is often
> > carefully made with all the laminates running in the same
direction.
> >
> > Obviously, this is all from house framing experience; for certain
> > well thought out applications in a boat, layered plywood might
> serve
> > as well or better than solid lumber. But you need to think about
> > what you are doing.
> >
> > gbb
Good points.
Plywood is used extensively for stringers in the powerboat world, all
they do is fit them as hollow box beams, and glass over them. this
would be easy to do on a small boat, either as a variation on a deck,
or as a means of caping something like blue foam. There would be a
certain amount of wast, since you would need to cut the curves, but
if you scarphed it, it wouldn't be all that bad.
-- In bolger@y..., "gbb132000" <gbb132000@y...> wrote:
Plywood is used extensively for stringers in the powerboat world, all
they do is fit them as hollow box beams, and glass over them. this
would be easy to do on a small boat, either as a variation on a deck,
or as a means of caping something like blue foam. There would be a
certain amount of wast, since you would need to cut the curves, but
if you scarphed it, it wouldn't be all that bad.
-- In bolger@y..., "gbb132000" <gbb132000@y...> wrote:
> It depends on the application. You have to remember thatalternating
> the grain direction in plywood has up sides and down sides.dimensions
>
> For instance, if you layered strips of plywood to the same
> as a 2 x 12 joist, it would not be near as strong as an actual 2 xserve
> 12, because 1/2 to 1/3 of the wood would have the grain running the
> wrong way.
>
> When you see engineered lumber, what LOOKS like plywood is often
> carefully made with all the laminates running in the same direction.
>
> Obviously, this is all from house framing experience; for certain
> well thought out applications in a boat, layered plywood might
> as well or better than solid lumber. But you need to think about
> what you are doing.
>
> gbb
To me it seems that the lumber framing in the 'Instant boats' is doing two
things:
It stiffens the panels to which it is attached, much as the web of a girder
does. For this, plywood with the major grain running longitudinally should
serve.
Where nail and glue construction is used, the solid lumber is there to give
something substantial to nail into - all those of us who have ever tried
nailing into the edge grain of plywood know that plywood will not perform
that task adequately.
Thai Sean mentions buying 'Build the Instant Boats', not the 'new' book.
Those plans are all nail and glue, rather than stitch and tape - 'Danger,
Will Robinson!'
Cheers
Derek
things:
It stiffens the panels to which it is attached, much as the web of a girder
does. For this, plywood with the major grain running longitudinally should
serve.
Where nail and glue construction is used, the solid lumber is there to give
something substantial to nail into - all those of us who have ever tried
nailing into the edge grain of plywood know that plywood will not perform
that task adequately.
Thai Sean mentions buying 'Build the Instant Boats', not the 'new' book.
Those plans are all nail and glue, rather than stitch and tape - 'Danger,
Will Robinson!'
Cheers
Derek
When I built my Chebacco, the only place I used framing was the transom and
hidden corners I couldn't stitch and tape.
Tape corners are so much stronger than the wood that most of the framing
timbers on a boat can be replaced with taped corners and you get a stronger
boat in the process.
Of course, you can't nail or screw the thing together then, but everything
is a tradeoff.
hidden corners I couldn't stitch and tape.
Tape corners are so much stronger than the wood that most of the framing
timbers on a boat can be replaced with taped corners and you get a stronger
boat in the process.
Of course, you can't nail or screw the thing together then, but everything
is a tradeoff.
----- Original Message -----
From: "gbb132000" <gbb132000@...>
To: <bolger@yahoogroups.com>
Sent: Monday, November 18, 2002 8:22 PM
Subject: [bolger] Re: Substituting plywood for lumber
| It depends on the application. You have to remember that alternating
| the grain direction in plywood has up sides and down sides.
|
| For instance, if you layered strips of plywood to the same dimensions
| as a 2 x 12 joist, it would not be near as strong as an actual 2 x
| 12, because 1/2 to 1/3 of the wood would have the grain running the
| wrong way.
|
| When you see engineered lumber, what LOOKS like plywood is often
| carefully made with all the laminates running in the same direction.
|
| Obviously, this is all from house framing experience; for certain
| well thought out applications in a boat, layered plywood might serve
| as well or better than solid lumber. But you need to think about
| what you are doing.
|
| gbb
|
| --- In bolger@y..., "rdchamberland" <cha62759@t...> wrote:
| > Thai Sean raises an interesting question on the instant boat
| > website www.instantboats.com
| >
| > Best read the original yourselves however in a nutshell he has
| > returned to southeast asia and wants to build a boat. Straight
| lumber
| > is not available to him. Whatever lumber he could find would have to
| > be hand planed to get the crooks out etc.
| >
| > He asks about the feasibility of building his boat almost entirely
| of
| > plywood.
| > Bob Chamberland
|
|
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01930, Fax: (978) 282-1349
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|
It depends on the application. You have to remember that alternating
the grain direction in plywood has up sides and down sides.
For instance, if you layered strips of plywood to the same dimensions
as a 2 x 12 joist, it would not be near as strong as an actual 2 x
12, because 1/2 to 1/3 of the wood would have the grain running the
wrong way.
When you see engineered lumber, what LOOKS like plywood is often
carefully made with all the laminates running in the same direction.
Obviously, this is all from house framing experience; for certain
well thought out applications in a boat, layered plywood might serve
as well or better than solid lumber. But you need to think about
what you are doing.
gbb
the grain direction in plywood has up sides and down sides.
For instance, if you layered strips of plywood to the same dimensions
as a 2 x 12 joist, it would not be near as strong as an actual 2 x
12, because 1/2 to 1/3 of the wood would have the grain running the
wrong way.
When you see engineered lumber, what LOOKS like plywood is often
carefully made with all the laminates running in the same direction.
Obviously, this is all from house framing experience; for certain
well thought out applications in a boat, layered plywood might serve
as well or better than solid lumber. But you need to think about
what you are doing.
gbb
--- In bolger@y..., "rdchamberland" <cha62759@t...> wrote:
> Thai Sean raises an interesting question on the instant boat
> website www.instantboats.com
>
> Best read the original yourselves however in a nutshell he has
> returned to southeast asia and wants to build a boat. Straight
lumber
> is not available to him. Whatever lumber he could find would have to
> be hand planed to get the crooks out etc.
>
> He asks about the feasibility of building his boat almost entirely
of
> plywood.
> Bob Chamberland
Thai Sean raises an interesting question on the instant boat
website www.instantboats.com
Best read the original yourselves however in a nutshell he has
returned to southeast asia and wants to build a boat. Straight lumber
is not available to him. Whatever lumber he could find would have to
be hand planed to get the crooks out etc.
He asks about the feasibility of building his boat almost entirely of
plywood.
Bob Chamberland
website www.instantboats.com
Best read the original yourselves however in a nutshell he has
returned to southeast asia and wants to build a boat. Straight lumber
is not available to him. Whatever lumber he could find would have to
be hand planed to get the crooks out etc.
He asks about the feasibility of building his boat almost entirely of
plywood.
Bob Chamberland