Plywood mast
Jeff, I have a book describing many types of hollow wooden masts,
including one consisting in a rectangular section with two sides of
plywood and two of lumber (say, front and back in lumber, port and
starboard in plywood). I'll look and post the scantling details.
Best, Pippo
including one consisting in a rectangular section with two sides of
plywood and two of lumber (say, front and back in lumber, port and
starboard in plywood). I'll look and post the scantling details.
Best, Pippo
--- In bolger@y..., jeff@g... wrote:
> I'm thinking of rebuilding the mast for my boat since I'm getting
the
> bug to be on the water this summer. It's a 18' X 3" mast and last
> time I used two 18' 2x4 pieces laminated together then cut down
with
> a power planer. They still warped out of place in this dry air.
>
> Has anyone made a mast of plywood layers? 1/2" ply laminated with
> epoxy. It would be 6 layers deep by 3" strips, say staggered on
the
> splices by 2 foot.
>
> Would this work? It would only take one sheet of 1/2" to do it.
>
> I have a spare sheet of 1/2" which made me ponder this.
>
> Jeff
THe problem is that a splice on the outside of a bend is going to take
a lot more stress than the inner two layers, so staggering the splices
won't help a whole lot. Maybe you could glass over the 45 degree
areas? Say several layers, not all ending in the same place?
What about a hollow plywood mast with uni glass put on it?
Or do you play with glass and epoxy that much?
a lot more stress than the inner two layers, so staggering the splices
won't help a whole lot. Maybe you could glass over the 45 degree
areas? Say several layers, not all ending in the same place?
What about a hollow plywood mast with uni glass put on it?
Or do you play with glass and epoxy that much?
--- In bolger@y..., jeff@g... wrote:
> Rich, good point on the plywood so scratch that idea, and I hadn't
> thought of the splicing of the current mast, I'll have to a good
> look, thanks.
>
> Otherwise it's to the lumber yard for a bunch of 1x4s. This time
> I'll laminate 4 layers of 1x4s. I think I can stagger the joints
> made of 45 degree cuts enough that I won't have to scarf them. Done
> right I think I can keep 2 feet distance between all joints with
none
> in line with each other.
>
> The mast is much bigger than the sail needs. I doesn't flex at all.
> The first one I built did as I tappered it to much but the second
one
> I had at Lake Texhoma didn't flex at all so I don't think the
splices
> will create a problem.
>
> Jeff
> --- In bolger@y..., richard@s... wrote:
> > 'Tis possible, but I would no recommend it.
> >
> > Plywood great panel strength comes from the crosswise layers.
These
> > layers eliminate the along the grain weakness of wood.
> > Ala "splitting". These same layers would work against you in a
mast
> > application. One two sides you would have only about 1/8" of wood
> > taking all the tension.
> > On the other two sides, you would have only half the layers
> oriented
> > in the right direction.
> >
> > Simple test, take a short piece of 3/4" ply about 3" wide and
break
> > it both sideways and thickways. Do the same with a solid board.
> >
> >
> > How bad is yours bent? To bad to be functional? Could you wack off
> > the down side with a bandsaw and attach it to the up side?
> >
> > --- In bolger@y..., jeff@g... wrote:
> > > I'm thinking of rebuilding the mast for my boat since I'm
getting
> > the
> > > bug to be on the water this summer. It's a 18' X 3" mast and
> last
> > > time I used two 18' 2x4 pieces laminated together then cut down
> > with
> > > a power planer. They still warped out of place in this dry air.
> > >
> > > Has anyone made a mast of plywood layers? 1/2" ply laminated
> with
> > > epoxy. It would be 6 layers deep by 3" strips, say staggered on
> > the
> > > splices by 2 foot.
> > >
> > > Would this work? It would only take one sheet of 1/2" to do it.
> > >
> > > I have a spare sheet of 1/2" which made me ponder this.
> > >
> > > Jeff
Rich, good point on the plywood so scratch that idea, and I hadn't
thought of the splicing of the current mast, I'll have to a good
look, thanks.
Otherwise it's to the lumber yard for a bunch of 1x4s. This time
I'll laminate 4 layers of 1x4s. I think I can stagger the joints
made of 45 degree cuts enough that I won't have to scarf them. Done
right I think I can keep 2 feet distance between all joints with none
in line with each other.
The mast is much bigger than the sail needs. I doesn't flex at all.
The first one I built did as I tappered it to much but the second one
I had at Lake Texhoma didn't flex at all so I don't think the splices
will create a problem.
Jeff
thought of the splicing of the current mast, I'll have to a good
look, thanks.
Otherwise it's to the lumber yard for a bunch of 1x4s. This time
I'll laminate 4 layers of 1x4s. I think I can stagger the joints
made of 45 degree cuts enough that I won't have to scarf them. Done
right I think I can keep 2 feet distance between all joints with none
in line with each other.
The mast is much bigger than the sail needs. I doesn't flex at all.
The first one I built did as I tappered it to much but the second one
I had at Lake Texhoma didn't flex at all so I don't think the splices
will create a problem.
Jeff
--- In bolger@y..., richard@s... wrote:
> 'Tis possible, but I would no recommend it.
>
> Plywood great panel strength comes from the crosswise layers. These
> layers eliminate the along the grain weakness of wood.
> Ala "splitting". These same layers would work against you in a mast
> application. One two sides you would have only about 1/8" of wood
> taking all the tension.
> On the other two sides, you would have only half the layers
oriented
> in the right direction.
>
> Simple test, take a short piece of 3/4" ply about 3" wide and break
> it both sideways and thickways. Do the same with a solid board.
>
>
> How bad is yours bent? To bad to be functional? Could you wack off
> the down side with a bandsaw and attach it to the up side?
>
> --- In bolger@y..., jeff@g... wrote:
> > I'm thinking of rebuilding the mast for my boat since I'm getting
> the
> > bug to be on the water this summer. It's a 18' X 3" mast and
last
> > time I used two 18' 2x4 pieces laminated together then cut down
> with
> > a power planer. They still warped out of place in this dry air.
> >
> > Has anyone made a mast of plywood layers? 1/2" ply laminated
with
> > epoxy. It would be 6 layers deep by 3" strips, say staggered on
> the
> > splices by 2 foot.
> >
> > Would this work? It would only take one sheet of 1/2" to do it.
> >
> > I have a spare sheet of 1/2" which made me ponder this.
> >
> > Jeff
'Tis possible, but I would no recommend it.
Plywood great panel strength comes from the crosswise layers. These
layers eliminate the along the grain weakness of wood.
Ala "splitting". These same layers would work against you in a mast
application. One two sides you would have only about 1/8" of wood
taking all the tension.
On the other two sides, you would have only half the layers oriented
in the right direction.
Simple test, take a short piece of 3/4" ply about 3" wide and break
it both sideways and thickways. Do the same with a solid board.
How bad is yours bent? To bad to be functional? Could you wack off
the down side with a bandsaw and attach it to the up side?
Plywood great panel strength comes from the crosswise layers. These
layers eliminate the along the grain weakness of wood.
Ala "splitting". These same layers would work against you in a mast
application. One two sides you would have only about 1/8" of wood
taking all the tension.
On the other two sides, you would have only half the layers oriented
in the right direction.
Simple test, take a short piece of 3/4" ply about 3" wide and break
it both sideways and thickways. Do the same with a solid board.
How bad is yours bent? To bad to be functional? Could you wack off
the down side with a bandsaw and attach it to the up side?
--- In bolger@y..., jeff@g... wrote:
> I'm thinking of rebuilding the mast for my boat since I'm getting
the
> bug to be on the water this summer. It's a 18' X 3" mast and last
> time I used two 18' 2x4 pieces laminated together then cut down
with
> a power planer. They still warped out of place in this dry air.
>
> Has anyone made a mast of plywood layers? 1/2" ply laminated with
> epoxy. It would be 6 layers deep by 3" strips, say staggered on
the
> splices by 2 foot.
>
> Would this work? It would only take one sheet of 1/2" to do it.
>
> I have a spare sheet of 1/2" which made me ponder this.
>
> Jeff
I'm thinking of rebuilding the mast for my boat since I'm getting the
bug to be on the water this summer. It's a 18' X 3" mast and last
time I used two 18' 2x4 pieces laminated together then cut down with
a power planer. They still warped out of place in this dry air.
Has anyone made a mast of plywood layers? 1/2" ply laminated with
epoxy. It would be 6 layers deep by 3" strips, say staggered on the
splices by 2 foot.
Would this work? It would only take one sheet of 1/2" to do it.
I have a spare sheet of 1/2" which made me ponder this.
Jeff
bug to be on the water this summer. It's a 18' X 3" mast and last
time I used two 18' 2x4 pieces laminated together then cut down with
a power planer. They still warped out of place in this dry air.
Has anyone made a mast of plywood layers? 1/2" ply laminated with
epoxy. It would be 6 layers deep by 3" strips, say staggered on the
splices by 2 foot.
Would this work? It would only take one sheet of 1/2" to do it.
I have a spare sheet of 1/2" which made me ponder this.
Jeff