Constuction Foam
 

It was mentioned to me that there was a construction foam being used
to replace rotted floor stingers. It was easily worked by hand carving
to match the hull floor and could be epoxyed to the fiberglass floor
and the floor boards could be screwed in to it. Unfortunately, my
friend didn't know the name of the foam. If anyone has heard of this
foam ,its properties, and where to get I would appreciate the
information. Or any information on replacing stingers on a 19' Oday
Rhodes.

Thanks,
JB

Constuction Foam
 

JB wrote:
It was mentioned to me that there was a construction foam being used
to replace rotted floor stingers. It was easily worked by hand carving
to match the hull floor and could be epoxyed to the fiberglass floor
and the floor boards could be screwed in to it.

Sort of, yes. Any foam core is going to need a rigid skin
over it to complete the structure. Molding fiberglass
stringers in place is pretty easy though.
BTW "easily worked" means different things to different
people. Some of this stuff can be carved pretty readily with
an X-acto knife or such. Some of it is better to be ground
to shape & thermo-formed.

Suggested reading
http://www.doityourself.com/stry/foamcorepanels

.... Unfortunately, my
friend didn't know the name of the foam. If anyone has heard of this
foam ,its properties, and where to get I would appreciate the
information. Or any information on replacing stingers on a 19' Oday
Rhodes.


There are about ten thousand different foams on the market.
I buy from airplane kit suppliers like
http://www.wicksaircraft.com/

In fact I have had good results using their 'Last-A-Foam'
which is very much cheaper than the high-dollar stuff like
Airex or Divinycell.

For your purpose, I'd suggest a denser foam core than for a
surface such as a deck or hull which is usually in the 4 ~ 6
pounds per cubic foot range (for comparison, water weighs
60 #/cf and wood from about 45 on up). There are many
suppliers a 18# and 25# foam, if you size it similar to wood
and put 3 layers of 16oz cloth as a skin over the foam &
filleted & bonded to the hull, your boat will be lighter and
stronger and the new floor members will never rot.

Fresh Breezes- Doug King

Constuction Foam
 

Good book:

http://www.4spe.org/training/products/1027.php


http://www.polycel.com/

Do you want foam in sheets for you to cut or pre molded foam?

Will you coat it with fiberglass or some type of sealer?

Constuction Foam
 

On Thu, 10 Aug 2006 12:15:47 -0600, "Bob Crantz"
wrote: {deleted}


Need 2" x 3" x 6" to 24" long stringers to attach floor boards. Would
like to epoxy to the hull and screw floor boards down. Hoping it would
not require fiber glassing but wouldn't mind using a sealer. Main
concern is ease of working to match hull curvature while allowing
adequate cutouts to permit water drainage.Secondary concern is, I want
it to outlast me, as this is the second time and I don't want to do it
again if I don't have to. It must also provide lateral strength to
centerboard trunk.

Thanks for the Help

JB

Constuction Foam
 

Why not put down drainage tubes (PVC pipes cut half- round), lay down some
wood joists (or columns that would lock in to the foam) to screw the
floorboards to and use pour in foam. Great flotation, less work and
tremendous strength.

Constuction Foam
 

On Thu, 10 Aug 2006 16:11:30 -0600, "Bob Crantz"
wrote:

Why not put down drainage tubes (PVC pipes cut half- round), lay down some
wood joists (or columns that would lock in to the foam) to screw the
floorboards to and use pour in foam. Great flotation, less work and
tremendous strength.


I don't understand, need to keep a space between the floor boards and
the hull while sailing to keep your feet dry. Boat will only drain
after it is out of the water or pumped out over the side. If I pour in
the foam without stringer type molds, the incoming water will be above
the floor boards. Did I misunderstand you?

JB

Constuction Foam
 

On 10 Aug 2006, DSK wrote:

. . . there was a construction foam being used
to replace rotted floor stingers. It was easily
worked by hand carving to match the hull floor
and could be epoxyed to the fiberglass floor
and the floor boards could be screwed in to it.

Sort of, yes. Any foam core is going to need a rigid
skin over it to complete the structure. Molding fiberglass
stringers in place is pretty easy though. BTW "easily
worked" means different things to different people.
Some of this stuff can be carved pretty readily with
an X-acto knife or such. Some of it is better to be ground
to shape & thermo-formed.

This and the related comments below are well and good . . . provided
one actually is referring under-sole stringers the primary function of
which is mostly just to act as a buffer and adhering means between
hull and floor as distinguished from - as is common in many new boat
designs today, especially of the mid-priced production boats
(Catalina, Hunter, Beneteau) whose under-sole (supposedly)
bonded-to-hull grid system is supposed to perform the additional
important function of very substantially reducing if not fully
preventing flexing of the hull - an function that arguably is all the
more important the larger and more massive (particularly if +/- 37')
the boat.

Unfortunately, what is claimed to be fully bonded is not always that
and what appears to be solid grids may be little more than glass or
other filler only seemingly solid but (because, as DSK might also have
noted, easily covered with an apparently but not necessarily
stress-bearing rigid glassed cover).

Who was it who "defined" what is sometimes referred to as "materials
engineering" as something alone the lines of calculating the
density/componnents of materials whose properties we don't fully
understand to accommodate forces we commonly underestimate in
conditions we guess we sometimes can predict?

Suggested reading
http://www.doityourself.com/stry/foamcorepanels

....

There are about ten thousand different foams on the
market. I buy from airplane kit suppliers like
http://www.wicksaircraft.com/
In fact I have had good results using their 'Last-A-Foam'
which is very much cheaper than the high-dollar stuff like
Airex or Divinycell.
For your purpose, I'd suggest a denser foam core than for
a surface such as a deck or hull which is usually in the 4 ~ 6
pounds per cubic foot range (for comparison, water weighs
60 #/cf and wood from about 45 on up). There are many
suppliers a 18# and 25# foam, if you size it similar to wood
and put 3 layers of 16oz cloth as a skin over the foam &
filleted & bonded to the hull, your boat will be lighter and
stronger and the new floor members will never rot.

Fresh Breezes- Doug King